CC - ONLINE EXAM

Question 1

1. 10 6th

A. Kilo
B. Mega
C. Milli
D. Micro

Answer 1

B. Mega

Question 2

2. The prefix which means 10 -9 is:

A. Micro
B. Milli
C. Nano
D. Pico

Answer 2

C. Nano

Question 3

3. Concentration expressed as the amount of solute per 100 parts of solution:

A. Molarity
B. Normality
C. Percent solution
D. Ratio

Answer 3

C. Percent solution

Question 4

4. Indication of relative concentration:

A. Dilution
B. Molarity
C. Normality
D. Ratio

Answer 4

A. Dilution

Question 5

5. What is the molarity of a solution that contains 18.7 grams of KCl in 500 mL (MW 74.5)?

A. 0.1
B. 0.5
C. 1.0
D. 5.0

Answer 5

B. 0.5

Rationale:

M = 18.7 g / (74.5)(0.5L) = 0.5 M

Question 6

6. How much 95% v/v alcohol is required to prepare 5L of 70% v/v alcohol?

A. 2.4 L
B. 3.5 L
C. 3.7 L
D. 4.4 L

Answer 6

C. 3.7 L

Rationale:

C1V1 = C2V2

V1 = (70)(5L) / 95 = 3.7 L

Question 7

7. A colorimetric method calls for the use of 0.1 mL serum, 5 mL of the reagent and 4.9 mL of water. What is the dilution of the serum in the final solution?

A. 1 to 5
B. 1 to 10
C. 1 to 50
D. 1 to 100

Answer 7

D. 1 to 100

Rationale:

Amount of serum: 0.1 mL

Total volume: 10 mL

Dilution: 0.1:10 or 1:100

Question 8

8. Convert 72 Fahrenheit to its Celsius equivalent:

A. 12.2C
B. 22.2C
C. 40.2C
D. 44.4C

Answer 8

B. 22.2C

Rationale:

C = 5/9 (F - 32)

= 5/9 (72 - 32)

= 22.2C

Question 9

9. Convert 100 Celsius to its Kelvin equivalent:

A. 73.15K
B. 173.15K
C. 273.15K
D. 373.15K

Answer 9

D. 373.15K

Rationale:

K = C + 273.15

= 100 + 273.15

= 373.15K

Question 10

10. Most basic pipette:

A. Automatic pipette
B. Glass pipette

Answer 10

B. Glass pipette

Question 11

11. Does not have graduations to the tip:

A. Mohr pipet
B. Serologic pipet
C. Micropipet
D. None of these

Answer 11

A. Mohr pipet

Rationale:

A Mohr pipet does not have graduations to the tip.

It is a self-draining pipet, but the tip should not be allowed to touch the vessel while the pipet is draining.

Question 12

12. Pipets are used with biologic fluids having a viscosity greater than that of water:

A. Mohr pipets
B. Ostwald-Folin pipets
C. Pasteur pipets
D. Volumeteric pipets

Answer 12

B. Ostwald-Folin pipets

Rationale:

Ostwald-Folin pipets are used with biologic fluids having a viscosity greater than that of water. They are blowout pipets, indicated by two etched continuous rings at the top.

Question 13

13. Pipette with BULB CLOSER TO THE DELIVERY TIP and are used for accurate measurement of VISCOUS FLUIDS, such as blood or serum:

A. Ostwald-Folin pipette
B. Volumetric pipette

Answer 13

A. Ostwald-Folin pipette

Question 14

14. Pipette with cylindrical glass bulb near the CENTER of the pipette that helps to distinguish them from other types of transfer pipettes.

A. Ostwald-Folin pipette
B. Volumetric pipette

Answer 14

B. Volumetric pipette

Question 15

15. Extremely inert, excellent temperature tolerance and chemical resistance; used for stir bars, stopcocks and tubing:

A. Polyethylene
B. Polycarbonate
C. Polystyrene
D. Teflon

Answer 15

D. Teflon

Rationale:

POLYETHYLENE
● Widely used in plastic ware, too, including test tubes, bottles, graduated tubes, stoppers, disposable transfer pipets, volumetric pipets, and test tube racks.
● May bind or absorb proteins, dyes, stains, and picric acid

POLYCARBONATE
● Used in tubes for centrifugation, graduated cylinders, and flasks
● Usable temperature range is broad: –100° C to +160° C
● Very strong plastic but is not suitable for use with strong acids, bases, and oxidizing agents
● May be autoclaved but with limitations

POLYSTYRENE
● Rigid, clear type of plastic that should not be autoclaved
● Used in an assortment of tubes, including capped graduated tubes and test tubes
● Not resistant to most hydrocarbons, ketones, and alcohols

TEFLON
● Widely used for manufacturing stirring bars, tubing, cryogenic vials, and bottle cap liners
● Almost chemically inert and is suitable for use at temperatures ranging from –270° C to +255° C
● Resistant to a wide range of chemical classes, including acids, bases, alcohol, and hydrocarbons

Question 16

16. Horizontal-head centrifuge:

A. Cytocentrifuge
B. Fixed-angle head centrifuge
C. Swinging bucket centrifuge
D. Ultracentifuge

Answer 16

C. Swinging bucket centrifuge

Rationale:

HORIZONTAL-HEAD OR SWINGING BUCKET CENTRIFUGE
● HORIZONTAL WHEN MOVING OR SPINNING
● VERITICAL WHEN NOT MOVING

Cups holding the tubes of material to be centrifuged occupy a vertical position when the centrifuge is at rest but assume a horizontal position when the centrifuge revolves

Question 17

17. It is used when rapid centrifugation of solutions containing small particles is needed; an example is the microhematocrit centrifuge:

A. Horizontal-head centrifuge
B. Fixed-angle head centrifuge
C. Ultracentrifuge
D. Cytocentrifuge

Answer 17

B. Fixed-angle head centrifuge

Question 18

18. High-speed centrifuges used to separate layers of different specific gravities, commonly used to separate lipoproteins:

A. Horizontal-head centrifuge
B. Fixed-angle head centrifuge
C. Ultracentrifuge
D. Cytocentrifuge

Answer 18

C. Ultracentrifuge

Rationale:

● High-speed centrifuges used to separate layers of different specific gravities
● Commonly used to separate lipoproteins

● Usually refrigerated to counter heat produced through friction

Question 19

19. Uses a very high-torque and low-inertia motor to spread MONOLAYER OF CELLS rapidly across a special slide for critical morphologic studies:

A. Horizontal-head centrifuge
B. Fixed-angle head centrifuge
C. Ultracentrifuge
D. Cytocentrifuge

Answer 19

D. Cytocentrifuge

Rationale: (6mm)

Uses a very high-torque and low-inertia motor to spread monolayers of cells rapidly across a special slide for critical morphologic studies

Used for blood, urine, body fluid, or any other liquid specimen that can be spread on a slide

Question 20

20. The speed of the centrifuge should be checked every 3 months with:

A. Tachometer
B. Wiper
C. Potentiometer
D. Ergometer

Answer 20

A. Tachometer

Question 21

21. Calibration of centrifuges is customarily performed every ______.

A. Daily
B. Weekly
C. Every 3 months (quarterly)
D. Yearly

Answer 21

C. Every 3 months (quarterly)

Rationale:

Photoelectric tachometer or strobe tachometer

CAP recommends that the number of revolutions per minute for a centrifuge used in chemistry laboratories be checked every 3 months and the appropriate relative centrifugal force for each setting is recorded.

Question 22

22. Centrifuges are routinely disinfected on a ___ basis.

A. Daily
B. Weekly
C. Monthly
D. Quarterly

Answer 22

B. Weekly

Question 23

23. HIGHLY PURIFIED SUBSTANCES of a known composition:

A. Control
B. Standard

Answer 23

B. Standard

Rationale:

A standard may differ from a control in its overall composition and in the way it is handled in the test.

Standards are the best way to measure ACCURACY. Standards are used to establish reference points in the construction of graphs (e.g., manual hemoglobin curve) or to calculate a test result.

Question 24

24. It represents a specimen that is SIMILAR IN COMPOSITION TO THE PATIENT’S WHOLE BLOOD or plasma:

A. Control
B. Standard

Answer 24

A. Control

Rationale:

The value of a control specimen is known. Control specimens are tested in exactly the same way as the patient specimen and are tested daily or in conjunction with the unknown (patient) specimen.

Controls are the best measurements of PRECISION and may represent normal or abnormal test values.

Question 25

25. Water produced using either an anion or a cation EXCHANGE RESIN, followed by replacement of the removed ions with hydroxyl or hydrogen ions.

A. Deionized water
B. Distilled water
C. RO water

Answer 25

A. Deionized water

Question 26

26. The PUREST TYPE OF REAGENT WATER is:

A. Type I
B. Type II
C. Type III
D. All are equal

Answer 26

A. Type I

Question 27

27. Chemicals that are used to manufacture drugs:

A. Technical or commercial grade
B. Analytical grade
C. Ultrapure grade
D. USP and NF chemical grade

Answer 27

D. USP and NF chemical grade

Question 28

28. Basic unit for mass:

A. Gram
B. Kilogram
C. Mole
D. Pound

Answer 28

B. Kilogram

Rationale:

BASE QUANTITY

1. Length (meter)
2. Mass (kilogram)
3. Time (second)
4. Electric current (ampere)
5. Thermodynamic temperature (Kelvin)
6. Amount of substance (mole)
7. Luminous intensity (Candela)

Question 29

29. Which of the following is NOT A COLLIGATIVE PROPERTY of solutions?

A. pH
B. Freezing point
C. Osmotic pressure
D. Vapor pressure

Answer 29

A. pH

Rationale:

The properties of osmotic pressure, vapor pressure, freezing point, and boiling point are called COLLIGATIVE PROPERTIES.

When a solute is dissolved in a solvent, these colligative properties change in a predictable manner for each osmole of substance present:

● FREEZING POINT IS LOWERED by −1.86°C
● VAPOR PRESSURE IS LOWERED by 0.3 mm Hg or torr
● OSMOTIC PRESSURE IS INCREASED by a factor of 1.7 × 104 mm Hg or torr
● BOILING POINT IS RAISED by 0.52°C

Question 30

30. Most clinical microbiology laboratories are categorized at what biosafety level?

A. 1
B. 2
C. 3
D. 4

Answer 30

B. 2

Question 31

31. Degree of hazard #2:

A. Slight
B. Moderate
C. Serious
D. Extreme

Answer 31

B. Moderate

Question 32

32. Electrical equipment fire:

A. Class A
B. Class B
C. Class C
D. Class D

Answer 32

C. Class C

Rationale:

Fires have been divided into four classes based on the nature of the combustible material and requirements for extinguishment:

● Class A: ordinary combustible solid materials, such as paper, wood, plastic, and fabric
● Class B: flammable liquids/gases and combustible petroleum products
● Class C: energized electrical equipment
● Class D: combustible/reactive metals, such as magnesium, sodium, and potassium

Question 33

33. Type of extinguisher for CLASS A FIRES:
    1. Pressurized water
    2. Dry chemical
    3. Carbon dioxide
    4. Halon

A. 1 and 2
B. 1 and 3
C. 1, 2 and 3
D. Only 1

Answer 33

A. 1 and 2

Rationale:

TYPE OF EXTINGUISHER (Bishop page 47)

● Class A: Pressurized water and dry chemical
● Class B: Dry chemical and carbon dioxide
● Class C: Dry chemical, carbon dioxide and halon
● Class D: Metal X

Question 34

34. All of the following are CRYOGENIC MATERIALS HAZARDS, EXCEPT:

A. Asphyxiation
B. Fire or explosion
C. Shock
D. Tissue damage similar to thermal burns

Answer 34

C. Shock

Rationale:

Liquid nitrogen is probably one of the most widely used cryogenic fluids (liquefied gases) in the laboratory.

There are, however, several hazards associated with the use of any cryogenic material: fire or explosion, asphyxiation, pressure buildup, embrittlement of materials, and tissue damage similar to that of thermal burns.

Question 35

35. Repetitive strain disorders such as tenosynovitis, bursitis, and ganglion cysts:

A. Cryogenic materials hazards
B. Electrical hazards
C. Ergonomic hazards
D. Mechanical hazards

Answer 35

C. Ergonomic hazards

Rationale:

The primary contributing factors associated with repetitive strain disorders are position/posture, applied force, and frequency of repetition.

Remember to consider the design of hand tools (e.g., ergonomic pipets), adherence to ergonomically correct technique, and equipment positioning when engaging in any repetitive task. Chronic symptoms of pain, numbness, or tingling in extremities may indicate the onset of repetitive strain disorders. Other hazards include acute musculoskeletal injury. Remember to lift heavy objects properly, keeping the load close to the body and using the muscles of the legs rather than the back. Gradually increase force when pushing or pulling, and avoid pounding actions with the extremities.

Question 36

36. The first step to take when attempting to repair electronic equipment is to:

A. Check all electronic connections
B. Turn instrument off and unplug it
C. Reset all the printed circuit boards
D. Review instrument manual

Answer 36

B. Turn instrument off and unplug it

Rationale:

Before REPAIR OR ADJUSTMENT of electrical equipment

The following should be done

1. unplug the equipment
2. make sure the hands are dry
3. remove jewelry.

Question 37

37. When a person is receiving an electrical shock, all of the following should be done EXCEPT:

A. Pull the person away from the electrical source
B. Turn off the circuit breaker
C. Move the electrical source using a glass object
D. Move the electrical source using a wood object

Answer 37

A. Pull the person away from the electrical source

Question 38

38. Most common source of light for work in the visible and near-infrared regions:

A. Deuterium discharge lamp and mercury arc lamp
B. Incandescent tungsten or tungsten-iodide lamp

Answer 38

B. Incandescent tungsten or tungsten-iodide lamp

Question 39

39. The lamps most commonly used for ultraviolet (UV) work are:

A. Deuterium discharge lamp and mercury arc lamp
B. Incandescent tungsten or tungsten-iodide lamp

Answer 39

A. Deuterium discharge lamp and mercury arc lamp

Question 40

40. Which is the most sensitive detector for spectrophotometry?

A. Photomultiplier
B. Phototube
C. Electron multiplier
D. Photodiode array

Answer 40

A. Photomultiplier

Rationale:

Because of this amplification, the PM tube is 200 times more sensitive than the phototube. PM tubes are used in instruments designed to be extremely sensitive to very low light levels and light flashes of very short duration.

Question 41

41. Reflectance spectrometry uses which of the following?

A. Luminometer
B. Tungsten–halogen lamp
C. Photomultiplier tube
D. UV lamp
E. Thermometer to monitor temperature in reaction

Answer 41

B. Tungsten–halogen lamp

Rationale:

● Slide technology depends on reflectance spectrophotometry.
● For colorimetric determinations, the light source is a tungsten–halogen lamp.

Question 42

42. Which of the following light sources is used in atomic absorption spectrophotometry?

A. Hollow-cathode lamp
B. Xenon arc lamp
C. Tungsten light
D. Deuterium lamp
E. Laser

Answer 42

A. Hollow-cathode lamp

Rationale:

The usual light source, known as a hollow-cathode lamp, consists of an evacuated gas-tight chamber containing an anode, a cylindrical cathode, and an inert gas, such as helium or argon.

Question 43

43. Used to measure concentration of LARGE PARTICLES:
    1. Nephelometry
    2. Turbidimetry
    3. Absorption spectroscopy

A. 1 only
B. 2 only
C. 1 and 2
D. 1, 2 and 3

Answer 43

C. 1 and 2

Rationale:

Nephelometry and turbidimetry are used to measure the concentrations of large particles (such as antigen–antibody complexes, prealbumin, and other serum proteins) that because of their size cannot be measured by absorption spectroscopy

Question 44

44. Temperature is _______ proportional to fluorescence.

A. Directly proportional
B. Inversely proportional
C. No effect

Answer 44

B. Inversely proportional

Question 45

45. Low temperature:

A. Increase in fluorescence
B. Decrease in fluorescence

Answer 45

A. Increase in fluorescence

Question 46

46. Which of the following techniques measures light scattered and has a light source placed at 90 degrees from the incident light?

A. Chemiluminescence
B. Atomic absorption spectrophotometry
C. Nephelometry
D. Turbidimetry

Answer 46

C. Nephelometry

Question 47

47. Which of the following instruments is used in the clinical laboratories to detect beta and gamma emissions?

A. Fluorometer
B. Nephelometer
C. Scintillation counter
D. Spectrophotometer

Answer 47

C. Scintillation counter

Question 48

48. Liquids (reagents, diluents, and samples) are pumped through a system of [continuous] tubing:

A. Continuous flow analysis
B. Centrifugal analysis
C. Discrete analysis
D. None of these

Answer 48

A. Continuous flow analysis

Question 49

49. Which of the following types of analyzers offers RANDOM-ACCESS CAPABILITIES?

A. Discrete analyzers
B. Continuous-flow analyzers
C. Centrifugal analyzers
D. None of these

Answer 49

A. Discrete analyzers

Rationale:

All three can use batch analysis (i.e., large number of specimens in one run), but only discrete analyzers offer random-access, or stat, capabilities.

Question 50

50. Checking instrument calibration, temperature accuracy, and electronic parameters are part of:

A. Preventive maintenance
B. Quality control
C. Function verification
D. Precision verification

Answer 50

C. Function verification

Rationale:

Function verification includes monitoring temperature, setting electronic parameters, calibrating instruments and analyzing control data.

Question 51

51. PLEASE CHECK THREE (3) BOXES: Measures of center.

o Coefficient of variation
o Mean
o Median
o Mode
o Range
o Standard deviation

Answer 51

o Mean
o Median
o Mode

Question 52

52. PLEASE CHECK THREE (3) BOXES: Measures of spread.

o Coefficient of variation
o Mean
o Median
o Mode
o Range
o Standard deviation

Answer 52

o Coefficient of variation
o Range
o Standard deviation

Rationale:

The spread represents the relationship of all the data points to the mean. There are three commonly used descriptions of spread: (1) range (2) standard deviation (SD), and (3) coefficient of variation (CV).

Question 53

53. Systematic errors include: PLEASE CHECK 3 BOXES.

o Calibrator reconstitution
o Electro-optical mechanism
o Environmental conditions
o Fluctuations in line voltage
o Instability of instrument
o Reagent dispensing
o Reagent lot variability
o Sample evaporation
o Temperature of analyzer
o Variation in handling techniques: pipetting, mixing, timing
o Variation in operators
o Wear and tear of instrument

Answer 53

o Fluctuations in line voltage
o Reagent lot variability
o Wear and tear of instrument

Rationale:

A SYSTEMATIC ERROR, on the other hand, will be seen as a trend in the data. Control values gradually rise (or fall) from the previously established limits. This type of error includes improper calibration, deterioration of reagents, sample instability, instrument drift, or changes in standard materials. All the Westgard rules that indicate trends identify systematic errors. 2(2S), 4(1S) and 10(x) rule.

SYSTEMATIC ERRORS MAY BE DUE TO:
● Aging reagents
● Aging calibrators
● Instrument components
● Optical changes
● Fluctuations in line voltage
● Wear and tear of instrument
● Reagent lot variability
● Calibration differences
● Technologist interactions

Question 54

54. Random errors include: PLEASE CHECK 3 BOXES.

o Aging reagents
o Aging calibrators
o Calibration differences
o Instrument components
o Fluctuations in line voltage
o Optical changes
o Reagent lot variability
o Reagent dispensing
o Technologist interactions
o Variation in handling techniques: pipetting, mixing, timing
o Variation in operator
o Wear and tear of instrument

Answer 54

o Reagent dispensing
o Variation in handling techniques: pipetting, mixing, timing
o Variation in operator

Rationale:

RANDOM ERROR is one with no trend or means of predicting it. Random errors include such situations as mislabeling a sample, pipetting errors, improper mixing of sample and reagent, voltage fluctuations not compensated for by instrument circuitry, and temperature fluctuations. Violations of the 1(2S), 1(3S) and R(4S) Westgard rules are usually associated with random error. To assess the situation, the sample is assayed using the same reagents. If a random error occurred, the same mistake may not be made again, and the result will be within appropriate control limits.

RANDOM ERRORS MAY BE DUE TO:

● Reagent dispensing
● Sample evaporation
● Temperature of analyzer
● Electro-optical mechanism
● Calibrator reconstitution
● Environmental conditions
● Instability of instrument
● Variation in handling techniques: pipetting, mixing, timing
● Variation in operators

Question 55

55. Most frequently occurring value in a dataset:

A. Mean
B. Median
C. Mode
D. Range

Answer 55

C. Mode

Rationale:

The mode is the most frequently occurring value in a dataset. Although it is seldom used to describe data, it is referred to when in reference to the shape of data, a bimodal distribution, for example.

Question 56

56. Type of systemic error in the sample direction and magnitude; the magnitude of change is constant and not dependent on the amount of analyte.

A. Constant systematic error
B. Proportional systematic error

Answer 56

A. Constant systematic error

Question 57

57. Type of systemic error where the magnitude changes as a percent of the analyte present; error dependent on analyte concentration.

A. Constant systematic error
B. Proportional systematic error

Answer 57

B. Proportional systematic error

Question 58

58. Difference between the observed mean and the reference mean:

A. Bias
B. Confidence interval
C. Parametric method
D. Nonparametric method

Answer 58

A. Bias

Rationale:

Bias: Difference between the observed mean and the reference mean.

Negative bias indicates that the test values tend to be lower than the reference value, whereas positive bias indicates test values are generally higher.

Bias is a type of constant systematic error.

Question 59

59. Ability of a test to detect a given disease or condition.

A. Analytic sensitivity
B. Analytic specificity
C. Diagnostic sensitivity
D. Diagnostic specificity

Answer 59

C. Diagnostic sensitivity

Question 60

60. Ability of a test to correctly identify the absence of a given disease or condition.

A. Analytic sensitivity
B. Analytic specificity
C. Diagnostic sensitivity
D. Diagnostic specificity

Answer 60

D. Diagnostic specificity

Question 61

61. Ability of a method to detect small quantities of an analyte.

A. Analytic sensitivity
B. Analytic specificity
C. Diagnostic sensitivity
D. Diagnostic specificity

Answer 61

A. Analytic sensitivity

Question 62

62. Ability of a method to detect only the analyte it is designed to determine.

A. Analytic sensitivity
B. Analytic specificity
C. Diagnostic sensitivity
D. Diagnostic specificity

Answer 62

B. Analytic specificity

Question 63

63. Positive predictive value:

A. Ability of a test to detect a given disease or condition.
B. Ability of a test to correctly identify the absence of a given disease or condition.
C. Chance of an individual having a given disease or condition if the test is abnormal.
D. Chance an individual does not have a given disease or condition if the test is within the reference interval.

Answer 63

C. Chance of an individual having a given disease or condition if the test is abnormal.

Question 64

64. Negative predictive value:

A. Ability of a test to detect a given disease or condition.
B. Ability of a test to correctly identify the absence of a given disease or condition.
C. Chance of an individual having a given disease or condition if the test is abnormal.
D. Chance an individual does not have a given disease or condition if the test is within the reference interval.

Answer 64

D. Chance an individual does not have a given disease or condition if the test is within the reference interval.

Question 65

65. What percentage of values will fall between ±2 s in a Gaussian (normal) distribution?

A. 34.13%
B. 68.26%
C. 95.45%
D. 99.74%

Answer 65

C. 95.45%

Rationale:

● 68.26% will lie within ±1s
● 95.45% will lie within ±2s
● 99.74% will lie within ±3s

Question 66

66. Two (2) consecutive control values exceed the same 2 standard deviation limit:

A. 1:2S
B. 2:2S
C. R:4S
D. 4:1S

Answer 66

B. 2:2S

Rationale:

Westgard multirule is a control procedure that utilizes control rules to assess numerical quality control data; the control rules establish the limits for data rejection in a system with two controls. Other rules apply when three controls are used.

1:2s = 1 control value exceeds the mean ±2 standard deviations; warning rule that triggers inspection of control values using the other rejection rules that follow; only rule that is not used to reject a run; results are reportable

1:3s = 1 control value exceeds the mean ±3 standard deviations; detects random error

2:2s = 2 consecutive control values exceed the same 2 standard deviation limit (same mean +2 s or same mean -2 s); detects systematic error

R:4s = 1 control value in a group exceeds the mean +2 s and a second control value exceeds the mean -2 s, creating a 4 standard deviation spread; detects random error

4:ls = 4 consecutive control values are recorded on one side of the mean and exceed either the same mean +1 s or the same mean -1 s; detects systematic error

10:x =10 consecutive control values are recorded on one side of the mean (either above or below the mean); detects systematic error

Question 67

67. The term R:4S means that:

A. Four consecutive controls are greater than ±1 standard deviation from the mean
B. Two controls in the same run are greater than 4s units apart
C. Two consecutive controls in the same run are each greater than ±4s from the mean
D. There is a shift above the mean for four consecutive controls

Answer 67

B. Two controls in the same run are greater than 4s units apart

Rationale:

The R:4s rule is applied to two control levels within the same run. The rule is violated when the algebraic difference between them (level 1 – level 2) exceeds 4s.

The R:4s rule detects random error (error due to poor precision).

Question 68

68. Error always in one direction:

A. Random error
B. Systematic error

Answer 68

B. Systematic error

Rationale:

Random error: error varies from sample to sample

Question 69

69. Which of the following terms refers to deviation from the true value caused by indeterminate errors inherent in every laboratory measurement?

A. Random error
B. Standard error of the mean
C. Parametric analysis
D. Nonparametric analysis

Answer 69

A. Random error

Rationale:

Random errors are deviations from the true value caused by unavoidable errors inherent in laboratory measurements.

The standard error of the mean is a statistical concept reflecting sampling variation. It is the standard deviation of the entire population.

Parametric statistics refer to a Gaussian (normal) distribution of data.

Nonparametric statistics are more general and require no assumptions.

Question 70

70. A trend in QC results is most likely caused by:

A. Deterioration of the reagent
B. Miscalibration of the instrument
C. Improper dilution of standards
D. Electronic noise

Answer 70

A. Deterioration of the reagent

Question 71

71. Which of the following plots is best for detecting all types of QC errors?

A. Levy–Jennings
B. Tonks–Youden
C. Cusum
D. Linear regression

Answer 71

A. Levy–Jennings

Rationale:

The Levy–Jennings plot is a graph of all QC results with concentration plotted on the y axis and run number on the x axis.

Question 72

72. Which of the following plots is best for comparison of precision and accuracy among laboratories?

A. Levy–Jennings
B. Tonks–Youden
C. Cusum
D. Linear regression

Answer 72

B. Tonks–Youden

Rationale:

The Tonks–Youden plot is used for interlaboratory comparison of monthly means. The method mean for level 1 is at the center of the y axis and mean for level 2 at the center of the x axis. Lines are drawn from the means of both levels across the graph, dividing it into four equal quadrants. If a laboratory’s monthly means both plot in the lower left or upper right, then systematic error (SE) exists in its method.

Question 73

73. Which plot will give the earliest indication of a shift or trend?

A. Levy–Jennings
B. Tonks–Youden
C. Cusum
D. Linear regression

Answer 73

C. Cusum

Rationale:

Cusum points are the algebraic sum of the difference between each QC result and the mean. The y axis is the sum of differences and the x axis is the run number. The center of the y axis is 0. Because QC results follow a random distribution, the points should distribute about the zero line. Results are out of control when the slope exceeds 45° or a decision limit (e.g., ±2.7s) is exceeded.

Question 74

74. Which of the following terms refers to the closeness with which the measured value agrees with the true value

A. Random error
B. Precision
C. Accuracy
D. Variance

Answer 74

C. Accuracy

Rationale:

The accuracy of an analytical result is the closeness with which the measured value agrees with the true value.

Precision is reproducibility.

Accuracy and precision are independent, but it is the goal of the clinical laboratory to design methods that are both precise and accurate.

Question 75

75. Relatively easy to measure and maintain:

A. Accuracy
B. Precision
C. Sensitivity
D. Specificity

Answer 75

B. Precision

Rationale:

Accuracy is easy to define but difficult to establish and maintain.

Precision is relatively easy to measure and maintain.

Question 76

76. Which of the following describes the ability of an analytical method to maintain both accuracy and precision over an extended period of time?

A. Reliability
B. Validity
C. Probability
D. Sensitivity

Answer 76

A. Reliability

Rationale:

The reliability of an analytical procedure is its ability to maintain accuracy and precision over an extended period of time during which supplies, equipment, and personnel in the laboratory may change. It is often used interchangeably with the term “consistency.” It is the goal of every clinical laboratory to produce reliable results.

Question 77

77. Which of the following statistical tests is used to compare the means of two methods?

A. Student’s t test
B. F distribution
C. Correlation coefficient (r)
D. Linear regression analysis

Answer 77

A. Student’s t test

Rationale:

T TEST: COMPARES MEANS, ACCURACY

F TEST: COMPARES S.D., PRECISION

Student’s t test is the ratio of mean difference to the standard error of the mean difference (bias/random error) and tests for a significant difference in means.

The F test is the ratio of variances and determines if one method is significantly less precise.

Question 78

78. In a person with normal glucose metabolism, the blood glucose level usually increases rapidly after carbohydrates are ingested but returns to a normal level after:

A. 30 minutes
B. 45 minutes
C. 60 minutes (1 hour)
D. 120 minutes (2 hours)

Answer 78

D. 120 minutes (2 hours)

Question 79

79. Glucose measurements can be ____ mg/dL erroneously higher by reducing methods than by more accurate enzymatic methods.

A. 1 to 5 mg/dL
B. 5 to 15 mg/dL
C. 20 to 25 mg/dL
D. 30 to 35 mg/dL

Answer 79

B. 5 to 15 mg/dL

Rationale:

Reduction methods also measure other reducing sugars.

Question 80

80. Select the enzyme that is most specific for beta D-glucose:

A. Glucose oxidase
B. Glucose-6-phosphate dehydrogenase
C. Hexokinase
D. Phosphohexose isomerase

Answer 80

A. Glucose oxidase

Rationale:

Glucose oxidase is the most specific enzyme reacting with only beta D-glucose. Glucose oxidase converts beta D-glucose to gluconic acid.

Mutarotase may be added to the reaction to facilitate the conversion of alpha-D-glucose to beta-D-glucose.

Question 81

81. Select the coupling enzyme used in the hexokinase method for glucose:

A. Glucose dehydrogenase
B. Glucose-6-phosphatase
C. Glucose-6-phosphate dehydrogenase
D. Peroxidase

Answer 81

C. Glucose-6-phosphate dehydrogenase (G6PD)

Rationale:

The hexokinase method is considered more accurate than the glucose oxidase methods because the coupling reaction using glucose-6-phosphate dehydrogenase is highly specific; therefore, it has less interference than the coupled glucose oxidase procedure.

Question 82

82. Which of the following is a potential source of error in the HEXOKINASE METHOD?

A. Galactosemia
B. Hemolysis
C. Sample collected in fluoride
D. Ascorbic acid

Answer 82

B. Hemolysis

Rationale:

Hemolyzed samples require a serum blank correction (subtraction of the reaction rate with hexokinase omitted from the reagent).

Question 83

83. Gross hemolysis and extremely elevated bilirubin may cause ______ in HEXOKINASE RESULTS.

A. False increase
B. False decrease
C. No effect
D. Variable

Answer 83

B. False decrease

Rationale:

Generally accepted as the reference method, hexokinase method is not affected by ascorbic acid or uric acid. Gross hemolysis and extremely elevated bilirubin may cause a false decrease in results.

Question 84

84. VERY LOW OR UNDETECTABLE C-peptide:

A. Type 1 diabetes mellitus
B. Type 2 diabetes mellitus

Answer 84

A. Type 1 diabetes mellitus

Question 85

85. DETECTABLE C-peptide:

A. Type 1 diabetes mellitus
B. Type 2 diabetes mellitus

Answer 85

B. Type 2 diabetes mellitus

Question 86

86. A 62-year-old patient presents to the physician with report of increased thirst and increased urination, particularly at night. The physician requests a series of tests over the next few days. The following data are received:

RANDOM GLUCOSE: 186 mg/dL
FASTING GLUCOSE: 114 mg/dL
2-HOUR OGTT: 153 mg/dL
HbA1c: 5.9%

Which of the following conclusions may be made regarding these data?

A. Data represents normal glucose status
B. Data represents an impaired glucose status
C. Data represents the presence of insulinoma
D. Data represents diagnosis of diabetes

Answer 86

B. Data represents an impaired glucose status

Rationale:

Resting plasma glucose

● NORMAL <140
● IMPAIRED 140 – 199
● DIAGNOSTIC ≥ 200 mg/dL

Fasting plasma glucose

● NORMAL <100
● IMPAIRED 100 – 125
● DIAGNOSTIC ≥ 126 mg/dL

2-hour OGTT

● NORMAL <140
● IMPAIRED 140 – 199
● DIAGNOSTIC ≥ 200 mg/dL

HbA1c

● NORMAL <5.7 %
● IMPAIRED 5.7 – 6.4%
● DIAGNOSTIC ≥ 6.5%

Question 87

87. What is the recommended cutoff value for adequate control of blood glucose in diabetics as measured by glycated hemoglobin?

A. 5%
B. 6.5%
C. 9.5%
D. 11%

Answer 87

B. 6.5%

Rationale:

If the result is 6.5% or more, the treatment plan should be adjusted to achieve a lower level, and the test performed every 3 months until control is improved.

Question 88

88. A factor, other than average plasma glucose values, that can affect the HbA1c level is:

A. Serum ketone bodies
B. Red blood cell life span
C. Ascorbic acid intake
D. Increased triglyceride levels

Answer 88

B. Red blood cell life span

Rationale:

Two factors determine the glycosylated hemoglobin levels: the average glucose concentration and the red blood cell life span.

If the red blood cell life span is decreased because of another disease state such as hemoglobinopathies, the hemoglobin will have less time to become glycosylated and the glycosylated hemoglobin level will be lower.

Question 89

90. Most widely used to assess SHORT-TERM (3 to 6 weeks) glycemic control:

A. Glycosylated hemoglobin (HbA1c)
B. Fructosamine

Answer 89

B. Fructosamine

Rationale:

FRUCTOSAMINE: GLYCOSYLATED ALBUMIN

Fructosamine assays are the most widely used to assess short-term (3 to 6 weeks) glycemic control because the average half-life of the proteins is 2–3 weeks.

Question 90

91. Formation of glucose-6-phosphate from noncarbohydrate sources:

A. Glycolysis
B. Gluconeogenesis
C. Glycogenolysis
D. Glycogenesis

Answer 90

B. Gluconeogenesis

Rationale:

● Glycolysis: Metabolism of glucose molecule to pyruvate or lactate for production of energy
● Gluconeogenesis: Formation of glucose-6-phosphate from noncarbohydrate sources
● Glycogenolysis: Breakdown of glycogen to glucose for use as energy
● Glycogenesis: Conversion of glucose to glycogen for storage
● Lipogenesis: Conversion of carbohydrates to fatty acids
● Lipolysis: Decomposition of fat

Question 91

92. HYPERGLYCEMIC FACTOR produced by the pancreas is:

A. Epinephrine
B. Glucagon
C. Growth hormone
D. Insulin

Answer 91

B. Glucagon

Rationale:

Glucagon is the primary hormone responsible for increasing glucose levels. It is synthesized by the ALPHA-cells of islets of Langerhans in the pancreas and released during stress and fasting states.

ACTION OF GLUCAGON

● Increases glycogenolysis: glycogen → glucose
● Increases gluconeogenesis: fatty acids → acetyl-CoA → ketone, proteins → amino acids

Question 92

93. HYPOGLYCEMIC FACTOR produced by the pancreas is:

A. Epinephrine
B. Glucagon
C. Growth hormone
D. Insulin

Answer 92

D. Insulin

Rationale:

Insulin is the only hormone that decreases glucose levels and can be referred to as a hypoglycemic agent.

Insulin is the primary hormone responsible for the entry of glucose into the cell. It is synthesized by the beta cells of islets of Langerhans in the pancreas.

It decreases plasma glucose levels by increasing the transport entry of glucose in muscle and adipose tissue by way of nonspecific receptors. It also regulates glucose by increasing glycogenesis, lipogenesis, and glycolysis and inhibiting glycogenolysis.

ACTION OF INSULIN

● Increases glycogenesis and glycolysis: glucose → glycogen → pyruvate → acetyl-CoA
● Increases lipogenesis
● Decreases glycogenolysis

Question 93

94. What would an individual with CUSHING SYNDROME tend to exhibit?

A. Hyperglycemia
B. Hypoglycemia
C. Normal blood glucose level
D. Decreased 2-hour postprandial glucose

Answer 93

A. Hyperglycemia

Rationale:

Hypercortisolism = Cushing’s Syndrome = Thyroid Problem
CORTISOL INCREASES BLOOD GLUCOSE.

Question 94

95. Symptoms of HYPOGLYCEMIA usually occur when blood glucose has fallen below ___ mg/dL.

A. Below 50 mg/dL
E. Below 60 mg/dL
F. Below 70 mg/dL
G. Below 80 mg/dL

Answer 94

A. Below 50 mg/dL

Question 95

96. Beta cell destruction, usually leading to absolute insulin deficiency:

A. Type 1 DM
B. Type 2 DM

Answer 95

A. Type 1 DM

Question 96

97. May range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance:

A. Type 1 DM
B. Type 2 DM

Answer 96

B. Type 2 DM

Question 97

98. Usual dose of LACTOSE in the oral lactose tolerance test is:

A. 25 grams
B. 50 grams
C. 75 grams
D. 100 grams

Answer 97

B. 50 grams

Rationale:

ORAL LACTOSE TOLERANCE TESTS, measuring the increase in plasma glucose or galactose following ingestion of lactose, have been used to diagnose lactase deficiency.

Question 98

99. Which of the following is the most common application of IMMUNOELECTROPHORESIS (IEP)?

A. Identification of the absence of a normal serum protein
B. Structural abnormalities of proteins
C. Screening for circulating immune complexes
D. Diagnosis of monoclonal gammopathies

Answer 98

D. Diagnosis of monoclonal gammopathies

Question 99

100. PRE-ECLAMPSIA, also referred to as TOXEMIA OF PREGNANCY is marked by specific symptoms including:

A. Water retention (with swelling particularly in the feet, legs, and hands)
B. High blood pressure
C. Protein in the urine
D. All of these

Answer 99

D. All of these

Question 100

101. A sensitive, although not specific indicator of damage to the kidneys:

A. Urea
B. Creatinine
C. Proteinuria
D. Cystatin C

Answer 100

C. Proteinuria

Question 101

102. At pH 8.6, proteins are _________ charged and migrate toward the _________.

A. Negatively, anode
B. Positively, cathode
C. Positively, anode
D. Negatively, cathode

Answer 101

A. Negatively, anode

Question 102

103. For albumin assay, absorbance at 630 nm is less likely to be affected by bilirubin or hemoglobin in the sample. Which dye gives a much greater absorbance change at 630 nm than it would at 500 nm?

A. HABA (Hydroxyazobenzene-benzoic acid)
B. BCG (Bromcresol green)

Answer 102

B. BCG (Bromcresol green)

Question 103

104. Which of the following dyes is the MOST SPECIFIC for measurement of albumin?

A. Bromcresol green (BCG)
B. Bromcresol purple (BCP)
C. Tetrabromosulfophthalein
D. Tetrabromphenol blue

Answer 103

B. Bromcresol purple (BCP)

Rationale:

BCP is more specific for albumin than BCG.

Question 104

105. In what condition would an increased level of serum albumin be expected?

A. Malnutrition
B. Acute inflammation
C. Dehydration
D. Renal disease

Answer 104

C. Dehydration

Question 105

106. ARTIFACTUAL INCREASE in albumin concentration:

A. Prolonged tourniquet application
B. Dehydration
C. Nephrotic syndrome
D. Inflammation

Answer 105

A. Prolonged tourniquet application

Question 106

107. Identification of which of the following is useful in early stages of glomerular dysfunction?

A. Microalbuminuria
B. Ketonuria
C. Hematuria
D. Urinary light chains

Answer 106

A. Microalbuminuria

Question 107

108. Most abundant amino acid in the body:

A. Glutamine
B. Lysine
C. Phenylalanine
D. Tyrosine

Answer 107

A. Glutamine

Rationale:

Glutamine is the most abundant amino acid in the body, being involved in more metabolic processes than any other amino acid.

Question 108

109. Precursor of the adrenal hormones epinephrine, norepinephrine, and dopamine and the thyroid hormones, including thyroxine:

A. Glutamine
B. Lysine
C. Phenylalanine
D. Tyrosine

Answer 108

D. Tyrosine

Rationale:

Tyrosine is a precursor of the adrenal hormones epinephrine, norepinephrine, and dopamine and the thyroid hormones, including thyroxine.

It is important in overall metabolism, aiding in the functions of the adrenal, thyroid, and pituitary glands.

Question 109

110. The plasma protein mainly responsible for maintaining colloidal osmotic pressure in vivo is:

A. Albumin
B. Hemoglobin
C. Fibrinogen
D. Alpha2-macroglobulin

Answer 109

A. Albumin

Rationale:

Albumin is responsible for nearly 80% of the colloid osmotic pressure (COP) of the intravascular fluid, which maintains the appropriate fluid balance in the tissue.

Question 110

111. Sensitive marker of poor nutritional status:

A. Prealbumin
B. Fibrinogen
C. Gc-globulin
D. Orosomucoid

Answer 110

A. Prealbumin

Rationale:

A low prealbumin level is a sensitive marker of poor nutritional status.

When a diet is deficient in protein, hepatic synthesis of proteins is reduced, with the resulting decrease in the level of the proteins originating in the liver, including prealbumin, albumin, and β-globulins. Because prealbumin has a short half-life of approximately 2 days, it decreases more rapidly than do other proteins.

Question 111

112. Nutritional assessment with poor protein-caloric status is associated with:

A. A decreased level of prealbumin
B. A low level of γ-globulins
C. An elevated ceruloplasmin concentration
D. An increased level of α1-fetoprotein

Answer 111

A. A decreased level of prealbumin

Question 112

113. Retinol (vitamin A) binding protein:

A. Albumin
B. Alpha1-antitrypsin
C. Fibronectin
D. Prealbumin

Answer 112

D. Prealbumin

Rationale:

Prealbumin is the transport protein for thyroxine and triiodothyronine (thyroid hormones); it also binds with retinol-binding protein to form a complex that transports retinol (vitamin A) and is rich in tryptophan.

Question 113

114. Which of the following conditions is the result of a LOW ALPHA1-ANTITRYPSIN LEVEL?

A. Asthma
B. Emphysema
C. Pulmonary hypertension
D. Sarcoidosis

Answer 113

B. Emphysema

Pulmonary Emphysema
Juvenile Hepatic Cirrhosis

Question 114

115. All are conditions associated with an elevated AFP, EXCEPT:

A. Neural tube defects
B. Spina bifida
C. Anencephaly
D. Down syndrome

Answer 114

D. Down syndrome

Rationale:

Conditions associated with an elevated AFP level include spina bifida, neural tube defects, abdominal wall defects, anencephaly (absence of the major portion of the brain), and general fetal distress.

Low levels of maternal AFP indicate an increased risk for Down syndrome (Trisomy 21) and trisomy 18 (Edward Syndrome), while it is increased in the presence of twins and neural tube defects.

Question 115

116. In nephrotic syndrome, the levels of serum ______ may increase as much as 10 times because its large size aids in its retention.

A. Alpha2-macroglobulin
B. Ceruloplasmin
C. Orosomucoid
D. Transferrin

Answer 115

A. Alpha2-macroglobulin

Rationale:

In nephrosis, the levels of serum α2-macroglobulin may increase as much as 10 times because its large size aids in its retention. The protein is also increased in diabetes and liver disease.

Use of contraceptive medications and pregnancy increase the serum levels by 20%.

Question 116

117. Orosomucoid:

A. Alpha1-antitrypsin
B. Alpha1-chymotrypsin
C. Alpha1-fetoprotein
D. Alpha1-acid glycoprotein

Answer 116

D. Alpha1-acid glycoprotein

Rationale:

α1-Acid Glycoprotein (Orosomucoid)

α1-Acid glycoprotein (AAG), a major plasma glycoprotein, is negatively charged even in acid solutions, a fact that gave it its name. This protein is produced by the liver and is an acute-phase reactant.

Question 117

118. Which of the following is a low-weight protein that is found on the cell surfaces of nucleated cells?

A. Alpha2-macroglobulin
B. Beta2-microglobulin
C. C-reactive protein
D. Ceruloplasmin

Answer 117

B. Beta2-microglobulin

Rationale:

β2-microglobulin is a single polypeptide chain that is the light chain component of human leukocyte antigens (HLAs). It is found on the surface of nucleated cells and is notably present on lymphocytes. Increased plasma levels of β2-microglobulin are associated with renal failure, lymphocytosis, rheumatoid arthritis, and systemic lupus erythematosus.

Question 118

119. Variants demonstrate a wide variety of cellular interactions, including roles in cell adhesion, tissue differentiation, growth, and wound healing:

A. Beta-trace protein
B. Cystatin C
C. Fibronectin
D. Troponin

Answer 118

C. Fibronectin

Question 119

120. A glycoprotein used to help predict the short-term risk of PREMATURE DELIVERY:

A. Adiponectin
B. Alpha-fetoprotein
C. Amyloid
D. Fetal fibronectin

Answer 119

D. Fetal fibronectin

Question 120

121. BIOCHEMICAL MARKER OF BONE RESORPTION that can be detected in serum and urine:

A. Beta-trace protein
B. Crosslinked C-telopeptides
C. Fibronectin
D. Troponin

Answer 120

B. Crosslinked C-telopeptides

Rationale:

Cross-linked C-telopeptides (CTXs) are proteolytic fragments of collagen I formed during bone resorption (turnover).

CTX is a biochemical marker of bone resorption that can be detected in serum and urine.

Question 121

122. An accurate marker of CSF leakage:

A. Beta-trace protein
B. Crosslinked C-telopeptides (CTX)
C. Fibronectin
D. Troponin

Answer 121

A. Beta-trace protein

Rationale:

β-Trace protein (BTP; synonym prostaglandin D synthase) is a 168–amino acid, low-molecular-mass protein in the lipocalin protein family. Recently, it was verified that BTP was established as an accurate marker of CSF leakage. It has also been reported recently as a potential marker in detecting impaired renal function, although no more sensitive than cystatin C.

Question 122

123. Recently proposed new marker for the early assessment of changes to the glomerular filtration rate:

A. Adiponectin
B. Beta-trace protein
C. Cross-linked C-telopeptides (CTX)
D. Cystatin C

Answer 122

D. Cystatin C

Question 123

124. Supplemental tests to help differentiate a diagnosis of ALZHEIMER DISEASE from other forms of dementia:

A. Amyloid β42 (Aβ42) and Tau protein
B. Crosslinked C-telopeptides (CTX)
C. Fibronectin
D. Troponin

Answer 123

A. Amyloid β42 (Aβ42) and Tau protein

Rationale:

In a symptomatic patient, low Aβ42 along with high Tau reflects an increased likelihood of Alzheimer disease, but it does not mean that the person definitely has Alzheimer disease. If a patient does not have abnormal levels of these proteins, then the dementia is more likely due to a cause other than Alzheimer disease.

Question 124

125. As a cardiac biomarker, this protein has been used in conjunction with troponin to help diagnose or rule out a heart attack:

A. Brain natriuretic peptide (BNP)
B. Cross-linked C-telopeptides (CTX)
C. Cystatin C
D. Myoglobin

Answer 124

D. Myoglobin

Rationale:

As a cardiac biomarker, myoglobin has been used in conjunction with troponin to help diagnose or rule out a heart attack. When striated muscle is damaged, myoglobin is released, elevating the blood levels.

In an AMI, this increase is seen within 2 to 3 hours of onset and reaches peak concentration in 8 to 12 hours. Myoglobin is a small molecule freely filtered by the kidneys, allowing levels to return to normal in 18 to 30 hours after the AMI.

Because of the speed of appearance and clearance of myoglobin, it is also a useful marker for monitoring the success or failure of reperfusion.

Question 125

126. “Gold standard” in the diagnosis of acute coronary syndrome (ACS):

A. Brain natriuretic peptide (BNP)
B. Cross-linked c-telopeptides
C. Myoglobin
D. Troponin

Answer 125

D. Troponin

Rationale:

ACUTE CORONARY SYNDROME/MYOCARDIAL INFARCTION

Cardiac troponin (cTn) represents a complex of regulatory proteins that include troponin I (cTnI) and troponin T (cTnT) that are specific to heart muscle.

cTnI and cTnT are the “gold standard” in the diagnosis of acute coronary syndrome (ACS). cTn should be measured in all patients presenting with symptoms suggestive of ACS, in conjunction with physical examination and ECG.

Question 126

127. Which test, if elevated, would PROVIDE INFORMATION about risk for developing coronary artery disease?

A. CK-MB
B. hs-CRP
C. Myoglobin
D. Troponin

Answer 126

B. hs-CRP

Rationale:

HIGH-SENSITIVITY CRP

Considered a GOOD PREDICTOR TEST for assessing cardiovascular risk

CK-MB, TROPONIN AND MYOGLOBIN

Used to assess if a myocardial infarction HAS OCCURRED

Question 127

128. If elevated, which laboratory test would support a diagnosis of CONGESTIVE HEART FAILURE?

A. Albumin cobalt binding
B. B-type natriuretic peptide
C. Homocysteine
D. Troponin

Answer 127

B. B-type natriuretic peptide

Rationale:

B-type (brain) natriuretic peptide (BNP) is used to determine if physical symptoms are related to congestive heart failure.

Question 128

129. Which two tests detect swelling of the ventricles that occurs in congestive heart failure?

A. BNP and electrocardiogram
B. BNP and echocardiogram
C. Troponin T and electrocardiogram
D. Troponin I and echocardiogram

Answer 128

A. BNP and electrocardiogram

Rationale:

DIAGNOSIS OF CONGESTIVE HEART FAILURE:

Until recently, this condition was diagnosed strictly on the basis of symptomatology and/or as a result of procedures such as echocardiography, but more recently a biomarker for this condition is the brain form or B-type natriuretic peptide (BNP), which has been approved as a definitive test for this condition and appears to be an excellent marker for early heart failure.

Question 129

130. Which of the following laboratory tests is a marker for ISCHEMIC HEART DISEASE?

A. Albumin cobalt binding
B. CK-MB isoforms
C. Free fatty acid binding protein
D. Myosin light chain

Answer 129

A. Albumin cobalt binding

Rationale:

Albumin cobalt binding is a test that measures ischemia-modified albumin, which is a marker for ischemic heart disease.

Question 130

131. The turbid, or milky, appearance of serum after fat ingestion is termed postprandial lipemia, which is caused by the presence of what substance?

A. Bilirubin
B. Cholesterol
C. Chylomicron
D. Phospholipid

Answer 130

C. Chylomicron

Rationale:

These chylomicrons enter the blood through the lymphatic system, where they impart a turbid appearance to serum

Question 131

132. When the plasma appears OPAQUE AND MILKY, the triglyceride level is probably:

A. Less than 100 mg/dL
B. Less than 200 mg/dL
C. Greater than 300 mg/dL
D. Greater than 600 mg/dL

Answer 131

D. Greater than 600 mg/dL

Rationale:

The appearance of the plasma or serum can be observed and noted after a minimum 12-hour fast.

If the plasma is clear, the triglyceride level is probably less than 200 mg/dL. When the plasma appears hazy or turbid, the triglyceride level has increased to greater than 300 mg/dL, and if the specimen appears opaque and milky (lipemic, from chylomicrons), the triglyceride level is probably greater than 600 mg/dL.

Note:

1. Clear plasma: TAG < 200 mg/dL
2. Hazy or turbid plasma: TAG > 300 mg/dL
3. Opaque or milky plasma: TAG > 600 mg/dL

Question 132

133. Which of the following tests would most likely be included in a routine lipid profile?

A. Total cholesterol, triglyceride, fatty acid, chylomicron
B. Total cholesterol, triglyceride, HDL cholesterol, phospholipid
C. Triglyceride, HDL cholesterol, LDL cholesterol, chylomicron
D. Total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol

Answer 132

D. Total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol

Question 133

134. To produce reliable results, when should blood specimens for lipid studies be drawn?

A. Immediately after eating
B. Anytime during the day
C. In the fasting state, approximately 2 to 4 hours after eating
D. In the fasting state, approximately 12 hours after eating

Answer 133

D. In the fasting state, approximately 12 hours after eating

Rationale:

Blood specimens for lipid studies should be drawn in the fasting state at least 9 to 12 hours after eating. Although fat ingestion only slightly affects cholesterol levels, the triglyceride results are greatly affected. Triglycerides peak at about 4 to 6 hours after a meal, and these exogenous lipids should be cleared from the plasma before analysis.

Question 134

135. Which of the following lipid tests is LEAST affected by the fasting status of the patient?

A. Cholesterol
B. Triglyceride
C. Fatty acid
D. Lipoprotein

Answer 134

A. Cholesterol

Rationale:

Total cholesterol screenings are commonly performed on nonfasting individuals.

Total cholesterol is only slightly affected by the fasting status of the individual, whereas triglycerides, fatty acids, and lipoproteins are greatly affected.

Question 135

136. The kinetic methods for quantifying serum triglyceride employ enzymatic hydrolysis. The hydrolysis of triglyceride may be accomplished by what enzyme?

A. Amylase
B. Leucine aminopeptidase
C. Lactate dehydrogenase
D. Lipase

Answer 135

Rationale:

It is first necessary to hydrolyze the triglycerides to free fatty acids and glycerol. This hydrolysis step is catalyzed by the enzyme lipase.

The glycerol is then free to react in the enzyme-coupled reaction system that includes glycerokinase, pyruvate kinase, and lactate dehydrogenase or in the enzyme-coupled system that includes glycerokinase, glycerophosphate oxidase, and peroxidase.

Question 136

137. The largest and the least dense of the lipoprotein particles:

A. LDL
B. HDL
C. VLDL
D. Chylomicrons

Answer 136

D. Chylomicrons

Rationale:

Chylomicrons, which contain apo B-48, are the largest and the least dense of the lipoprotein particles.

HDL, the smallest and most dense lipoprotein particle, is synthesized by both the liver and the intestine.

Question 137

138. The smallest and most dense lipoprotein particle:

A. LDL
B. HDL
C. VLDL
D. Chylomicrons

Answer 137

B. HDL

Question 138

139. An abnormal lipoprotein present in patients with biliary cirrhosis or cholestasis:

A. LDL
B. B-VLDL
C. Lp(a)
D. LpX

Answer 138

D. LpX

Rationale:

Lipoprotein X is an abnormal lipoprotein present in patients with biliary cirrhosis or cholestasis and in patients with mutations in lecithin:cholesterol acyltransferase (LCAT), the enzyme that esterifies cholesterol.

Question 139

140. Exogenous triglycerides are transported in the plasma in what form?

A. Phospholipids
B. Cholestryl esters
C. Chylomicrons
D. Free fatty acids

Answer 139

C. Chylomicrons

Rationale:

From the epithelial cells, the chylomicrons are released into the lymphatic system, which transports chylomicrons to the blood. The chylomicrons may then carry the triglycerides to adipose tissue for storage, to organs for catabolism, or to the liver for incorporation of the triglycerides into very-low-density lipoproteins (VLDLs). Chylomicrons are normally cleared from plasma within 6 hours after a meal.

Question 140

141. Select the lipoprotein fraction that carries most of the endogenous triglycerides.

A. VLDL
B. HDL
C. LDL
D. Chylomicrons

Answer 140

A. VLDL

Rationale:

VLDL transports the majority of endogenous triglycerides, while the triglycerides of chylomicrons are derived entirely from dietary absorption.

Question 141

142. Each lipoprotein fraction is composed of varying amounts of lipid and protein components. The beta-lipoprotein fraction consists primarily of which lipid?

A. Fatty acid
B. Cholesterol
C. Phospholipid
D. Triglyceride

Answer 141

B. Cholesterol

Rationale:

The beta-lipoprotein fraction is composed of approximately 50% cholesterol, 6% triglycerides, 22% phospholipids, and 22% protein.

The beta-lipoproteins, which are also known as the low-density lipoproteins (LDLs), are the principal transport vehicle for cholesterol in the plasma.

Question 142

143. The protein composition of HDL is what percentage by weight?

A. Less than 2%
B. 25%
C. 50%
D. 90%

Answer 142

C. 50%

Rationale:

About 50% of the weight of HDL is protein, largely apo A-I and apo A-II. The HDL is about 30% phospholipid and 20% cholesterol by weight.

Question 143

144. High levels of cholesterol leading to increased risk of coronary artery disease would be associated with which lipoprotein fraction?

A. LDL
B. VLDL
C. HDL
D. Chylomicrons

Answer 143

A. LDL

Question 144

145. What is the sedimentation nomenclature associated with alpha-lipoprotein?

A. Very-low-density lipoproteins (VLDLs)
B. High-density lipoproteins (HDLs)
C. Low-density lipoproteins (LDLs)
D. Chylomicrons

Answer 144

B. High-density lipoproteins (HDLs)

Rationale:

The HDLs, also known as the alpha-lipoproteins, have the greatest density of 1.063-1.210 g/mL and move the fastest electrophoretically toward the anode.

Question 145

146. The quantification of the high-density lipoprotein cholesterol level is thought to be significant in the risk assessment of what disease?

A. Pancreatitis
B. Cirrhosis
C. Coronary artery disease
D. Hyperlipidemia

Answer 145

C. Coronary artery disease

Rationale:

The quantification of the HDL cholesterol level is thought to contribute in assessing the risk that an individual may develop coronary artery disease (CAD).

There appears to be an inverse relationship between HDL cholesterol and CAD. With low levels of HDL cholesterol, the risk of CAD increases.

Question 146

147. Coronary heart disease POSITIVE risk factor:

A. LDL-C concentration < 100 mg/dL
B. HDL-C concentration ≥ 60 mg/dL
C. HDL-C concentration < 40 mg/dL
D. None of these

Answer 146

C. HDL-C concentration < 40 mg/dL

Rationale:

POSITIVE (INCREASED) RISK FACTORS

● Age: ≥ 45 y for men; ≥ 55 y or premature menopause for women
● Family history of premature CHD
● Current cigarette smoking
● Hypertension (blood pressure ≥ 140/90 mm Hg or taking antihypertensive medication)
● LDL-C concentration ≥ 160 mg/dL (≥ 4.1 mmol/L), with ≤ 1 risk factor
● LDL-C concentration ≥ 130 mg/dL (3.4 mmol/L), with ≥ 2 risk factors
● LDL-C concentration ≥ 100 mg/dL (2.6 mmol/L), with CH D or risk equivalent
● HDL-C concentration < 40 mg/dL (< 1.0 mmol/L)
● Diabetes mellitus = CH D risk equivalent
● Metabolic syndrome (multiple metabolic risk factors)

NEGATIVE (DECREASED) RISK FACTORS

● HDL-C concentration ≥ 60 mg/dL (≥ 1.6 mmol/L)
● LDL-C concentration < 100 mg/dL (< 2.6 mmol/L)

Question 147

148. Which apoprotein is inversely related to risk of coronary heart disease?

A. Apoprotein A-I
B. Apoprotein B100
C. Apoprotein C-II
D. Apoprotein E4

Answer 147

A. Apoprotein A-I

Rationale:

Apoprotein A-I and apo A-II are the principal apoproteins of HDL, and low apo A-I has a high correlation with atherosclerosis. Conversely, apo-B100 is the principal apoprotein of LDL, and an elevated level is a major risk factor in developing coronary heart disease.

Question 148

149. LDL primarily contains:

A. Apo AI
B. Apo-AII
C. Apo-B100
D. Apo-B48

Answer 148

C. Apo-B100

Rationale:

LDL primarily contains apo B-100 and is more cholesterol rich than other apo B–containing lipoproteins.

Note:

● Apo-AI, Apo-AII = HDL
● Apo-B100 = LDL, VLDL
● Apo-B48 = chylomicrons

Question 149

150. The VLDL fraction primarily transports what substance?

A. Cholesterol
B. Chylomicron
C. Triglyceride
D. Phospholipid

Answer 149

C. Triglyceride

Question 150

151. A commonly used precipitating reagent to separate HDL cholesterol from other lipoprotein cholesterol fractions:

A. Zinc sulfate
B. Trichloroacetic acid
C. Heparin-manganese
D. Isopropanol

Answer 150

C. Heparin-manganese

Rationale:

Either a dextran sulfate-magnesium chloride mixture or a heparin sulfate-manganese chloride mixture may be used to precipitate the LDL and VLDL cholesterol fractions. This allows the HDL cholesterol fraction to remain in the supernatant.

Question 151

152. Which of the following is associated with Tangier disease?

A. Apoprotein C-II deficiency
B. Homozygous apo-B100 deficiency
C. Apoprotein C-II activated lipase
D. Apoprotein A-I deficiency

Answer 151

D. Apoprotein A-I deficiency

Rationale:

Deficiency of apo A-I is seen in Tangier disease, a familial hypocholesterolemia.

Question 152

153. A patient’s total cholesterol is 300 mg/dL, his HDL cholesterol is 50 mg/dL, and his triglyceride is 200 mg/dL. What is this patient’s calculated LDL cholesterol?

A. 200
B. 210
C. 290
D. 350

Answer 152

B. 210

Rationale:

Once the total cholesterol, triglyceride, and HDL cholesterol are known, LDL cholesterol can be quantified by using the Friedewald equation

LDL cholesterol = Total cholesterol — (HDL cholesterol + Triglyceride/5)

In this example, all results are in mg/dL:

LDL cholesterol

= 300 - (50 + 200/5)
= 300 - (90)
= 210 mg/dL

Question 153

154. The Friedewald formula is not valid for triglycerides over_____.

A. Triglycerides over 100 mg/dL
B. Triglycerides over 200 mg/dL
C. Triglycerides over 300 mg/dL
D. Triglycerides over 400 mg/dL

Answer 153

D. Triglycerides over 400 mg/dL

Rationale:

LDL cholesterol may be calculated or measured directly:

1. Friedewald formula

Indirect, not valid for triglycerides over 400mg/dL

LDL cholesterol = total cholesterol — [HDL cholesterol + triglyceride/5]

2. Homogeneous assay uses detergents to block HDL and VLDL from reacting with the dye to form a colored chromogen product. An enzymatic cholesterol analysis is performed with only LDL cholesterol able to react.

Question 154

155. Select the order of mobility of lipoproteins electrophoresed on cellulose acetate or agarose at pH 8.6.

A. – Chylomicrons→pre-β →β→α+
B. – β→pre-β→α→chylomicrons +
C. – Chylomicrons →β→pre-β→α +
D. – α→β→pre-β→chylomicrons +

Answer 154

C. – Chylomicrons →β→pre-β→α +

Rationale:

Although pre-β lipoprotein is lower in density than β lipoprotein, it migrates faster on agarose or cellulose acetate owing to its more negative apoprotein composition.

LIPOPROTEINS

1. By electrophoresis

From the origin: chylomicrons > beta (LDL) > prebeta (VLDL) > alpha (HDL) Anode

2. By ultracentrifugation

From the least dense and largest: chylomicrons > VLDL > LDL > HDL most dense and smallest

Question 155

156. Floating beta lipoprotein:

A. Lp(a)
E. B-VLDL

Answer 155

E. B-VLDL

Rationale:

β-VLDL (‘floating β’ lipoprotein) is an abnormal lipoprotein that accumulates in type 3 hyperlipoproteinemia. It is richer in cholesterol than VLDL and apparently results from the defective catabolism of VLDL. The particle is found in the VLDL density range but migrates electrophoretically with or near LDL.

Question 156

157. Sinking pre-β-lipoprotein:

A. Lp(a)
B. B-VLDL

Answer 156

B. B-VLDL

Rationale:

Lp(a) has a density similar to LDL, but migrates similarly to VLDL on electrophoresis. Thus it can be detected when the d > 1.006 g/mL protein is examined electrophoretically. When Lp(a) is present in concentrations exceeding 20-30 mg/dL (i.e., when it contributes more than about 10 mg/dL to the LDL-C measurement) an additional band with pre-β mobility is also observed in the d > 1.006 kg/L fraction (hence the name sinking pre-β-lipoprotein).

Question 157

158. Which of the following may be described as a variant form of LDL, associated with increased risk of atherosclerotic cardiovascular disease?

A. Lp(a)
B. HDL
C. Apo-AI
D. Apo-AII

Answer 157

A. Lp(a)

Rationale:

Lipoprotein (a) is an apolipoprotein that is more commonly referred to as Lp(a). Although it is related structurally to LDL, Lp(a) is considered

to be a distinct lipoprotein class with an electrophoretic mobility in the prebeta region.

Lp(a) is believed to interfere with the lysis of clots by competing with plasminogen in the coagulation cascade, thus increasing the likelihood of atherosclerotic cardiovascular disease.

Question 158

159. Type V hyperlipoproteinemia:

A. Extremely elevated TG due to the presence of chylomicrons
B. Elevated LDL and VLDL
C. Elevated VLDL
D. Elevated VLDL and presence of chylomicrons

Answer 158

D. Elevated VLDL and presence of chylomicrons

Rationale:

BLOOD LIPOPROTEIN PATTERNS IN PATIENTS WITH HYPERLIPOPROTEINEMIA

● Type I: Extremely elevated TG due to the presence of chylomicrons
● Type IIa: Elevated LDL
● Type IIb: Elevated LDL and VLDL
● Type III: Elevated cholesterol, TG; presence of B-VLDL
● Type IV: Elevated VLDL
● Type V: Elevated VLDL and presence of chylomicrons

Question 159

160. It is the result of POOR PERFUSION of the kidneys and therefore diminished glomerular filtration. The kidneys are otherwise normal in their functioning capabilities. Poor perfusion can result from dehydration, shock, diminished blood volume, or congestive heart failure.

A. Pre-renal azotemia
B. Renal azotemia
C. Post-renal azotemia

Answer 159

A. Pre-renal azotemia

Question 160

161. It is caused primarily by DIMINISHED GLOMERULAR FILTRATION as a consequence of acute or chronic renal disease. Such diseases include acute glomerulonephritis, chronic glomerulonephritis, polycystic kidney disease, and nephrosclerosis.

A. Pre-renal azotemia
B. Renal azotemia
C. Post-renal azotemia

Answer 160

B. Renal azotemia

Question 161

162. It is usually the result of any type of OBSTRUCTION in which urea is reabsorbed into the circulation. Obstruction can be caused by stones, an enlarged prostate gland, or tumors.

A. Pre-renal azotemia
B. Renal azotemia
C. Post-renal azotemia

Answer 161

C. Post-renal azotemia

Question 162

163. Urea is produced from:

A. The catabolism of proteins and amino acids
B. Oxidation of pyrimidines
C. The breakdown of complex carbohydrates
D. Oxidation of purines

Answer 162

A. The catabolism of proteins and amino acids

Rationale:

Urea is generated by deamination of amino acids. Most is derived from the hepatic catabolism of proteins. Uric acid is produced by the catabolism of purines. Oxidation of pyrimidines produces orotic acid.

Question 163

164. Creatinine is formed from the:

A. Oxidation of creatine
B. Oxidation of protein
C. Deamination of dibasic amino acids
D. Metabolism of purines

Answer 163

A. Oxidation of creatine

Question 164

165. The red complex developed in the Jaffe method to determine creatinine measurements is a result of the complexing of creatinine with which of the following?

A. Alkaline picrate
B. Diacetyl monoxide
C. Sulfuric acid
D. Sodium hydroxide

Answer 164

A. Alkaline picrate

Question 165

166. The most widely used test of overall renal function is:

A. Urea
B. Creatinine
C. Proteinuria
D. Cystatin C

Answer 165

B. Creatinine

Question 166

168. Uric acid is derived from the:

A. Oxidation of proteins
B. Catabolism of purines
C. Oxidation of pyrimidines
D. Reduction of catecholamines

Answer 166

B. Catabolism of purines

Rationale:

Uric acid is the principal product of purine (adenosine and guanosine) metabolism.

Question 167

167. What substance may be measured as an alternative to creatinine for evaluating GFR?

A. Plasma urea
B. Cystatin C
C. Uric acid
D. Potassium

Answer 167

B. Cystatin C

Question 168

169. Which of the following is measured using glutamate dehydrogenase and is a measure of advanced stages, poor prognosis, and coma in liver disease?

A. Total bilirubin
B. Ammonia
C. Unconjugated bilirubin
D. Urea

Answer 168

B. Ammonia

Rationale:

Severe liver disease is the most common cause of altered ammonia metabolism. Therefore the monitoring of ammonia levels may be used to determine prognosis.

Question 169

170. Blood ammonia levels are usually measured in order to evaluate:

A. Renal failure
B. Acid–base status
C. Hepatic coma
D. Gastrointestinal malabsorption

Answer 169

C. Hepatic coma

Rationale:

Hepatic coma is caused by accumulation of ammonia in the brain as a result of liver failure. The ammonia increases central nervous system pH and is coupled to glutamate, a central nervous system neurotransmitter, forming glutamine. Blood and cerebrospinal fluid ammonia levels are used to distinguish encephalopathy caused by cirrhosis or other liver disease from nonhepatic causes and to monitor patients with hepatic coma.

Question 170

171. What is the compound that comprises the majority of the nonprotein-nitrogen fractions in serum?

A. Uric acid
B. Creatinine
C. Ammonia
D. Urea

Answer 170

D. Urea

Rationale:

UREA > AMINO ACIDS > URIC ACID > CREATININE > CREATINE > AMMONIA

Constituents in the plasma that contain the element nitrogen are categorized as being protein- or nonprotein-nitrogen compounds. The principal substances included among the nonprotein-nitrogen compounds are urea, amino acids, uric acid, creatinine, creatine, and ammonia.

Of these compounds, urea is present in the plasma in the greatest concentration, comprising approximately 45% of the nonprotein-nitrogen fraction.

Question 171

172. Urea concentration is calculated from the BUN by multiplying by a factor of:

A. 0.5
B. 2.14
C. 6.45
D. 14

Answer 171

B. 2.14

Question 172

173. Express 30 mg/dL of urea nitrogen as urea.

A. 14 mg/dL
B. 20 mg/dL
C. 50 mg/dL
D. 64 mg/dL

Answer 172

D. 64 mg/dL

Rationale:

30 x 2.14 = 64.2 mg/dL

When it is necessary to convert urea nitrogen values to urea, the concentration may be calculated easily by multiplying the urea nitrogen value by 2.14.

This factor is derived from the molecular mass of urea (60 daltons) and the molecular weight of its two nitrogen atoms (28)

Question 173

174. In the urea method, the enzymatic action of urease is inhibited when blood for analysis is drawn in a tube containing what anticoagulant?

A. Sodium heparin
B. Sodium fluoride
C. Sodium oxalate
D. EDTA

Answer 173

B. Sodium fluoride

Rationale:

With the urease reagent systems for the quantification of urea, the use of sodium fluoride must be avoided because of its inhibitory effect on this system.

Question 174

175. In the diacetyl method, what does diacetyl react with to form a yellow product?

A. Ammonia
B. Urea
C. Uric acid
D. Nitrogen

Answer 174

B. Urea

Question 175

176. Which of the following disorders is NOT associated with an elevated blood ammonia level?

A. Reye syndrome
B. Renal failure
C. Chronic liver failure
D. Diabetes mellitus

Answer 175

D. Diabetes mellitus

Question 176

177. When measuring ammonia blood levels, which of the following might cause a false increase in this analyte?

A. The patient had two cigarettes 15 minutes prior to blood draw.
B. The patient was fasting for hours prior to blood collection.
C. Immediately after phlebotomy, the blood sample was maintained on ice.
D. The patient had a steak dinner the night before the blood draw.
E. None of the above will falsely increase the blood ammonia levels.

Answer 176

A. The patient had two cigarettes 15 minutes prior to blood draw.

Rationale:

Cigarette smoking by the patient is a significant source of ammonia contamination. It is recommended that patients do not smoke for several hours before a specimen is collected.

Question 177

178. The assay for urea is only a rough estimate of renal function and will not show any significant level of increased concentration until the glomerular filtration rate is decreased by at least _____.

A. Glomerular filtration rate is decreased by at least 50%
B. Glomerular filtration rate is decreased by at least 60%
C. Glomerular filtration rate is decreased by at least 70%
D. Glomerular filtration rate is decreased by at least 80%

Answer 177

A. Glomerular filtration rate is decreased by at least 50%

Rationale:

The assay for urea is only a rough estimate of renal function and will not show any significant level of increased concentration until the glomerular filtration rate is decreased by at least 50%.

A more reliable single index of renal function is the test for serum creatinine. Contrary to urea concentration, creatinine concentration is relatively independent of protein intake (from the diet), degree of hydration, and protein metabolism.

Question 178

179. What compound normally found in urine may be used to assess the completeness of a 24-hour urine collection?

A. Urea
B. Uric acid
C. Creatine
D. Creatinine

Answer 178

D. Creatinine

Rationale:

The quantity of creatinine formed daily is a relatively constant amount because it is related to muscle mass.

Therefore, it has been customary to quantify the creatinine present in a 24-hour urine specimen as an index of the completeness of the collection.

Question 179

180. When mixed with phosphotungstic acid, what compound causes the reduction of the former to a tungsten blue complex?

A. Urea
B. Ammonia
C. Creatinine
D. Uric acid

Answer 179

D. Uric acid

Rationale:

Uric acid may be quantified by reacting it with phosphotungstic acid reagent in alkaline solution.

Question 180

181. Which of the following disorders is best characterized by laboratory findings that include increased serum levels of inorganic phosphorus, magnesium, potassium, uric acid, urea, and creatinine and decreased serum calcium and erythropoietin levels?

A. Chronic renal failure
B. Renal tubular disease
C. Nephrotic syndrome
D. Acute glomerulonephritis

Answer 180

A. Chronic renal failure

Rationale:

As renal function continues to be lost over time, chronic renal failure develops. Chronic renal failure is manifested by loss of excretory function, inability to regulate water and electrolyte balance, and increased production of parathyroid hormone, all of which contribute to the abnormal laboratory findings. The decreased production of erythropoietin causes anemia to develop.

Question 181

182. In gout, what analyte deposits in joints and other body tissues?

A. Calcium
B. Creatinine
C. Urea
D. Uric acid

Answer 181

D. Uric acid

Rationale:

Gout is a pathological condition that may be caused by a malfunction of purine metabolism or a depression in the renal excretion of uric acid. Two of the major characteristics of gout are hyperuricemia and a deposition of uric acid as monosodium urate crystals in joints, periarticular cartilage, bone, bursae, and subcutaneous tissue.

Question 182

183. A complete deficiency of hypoxanthine guanine phosphoribosyl transferase results in which disease?

A. Lesch-Nyhan syndrome
B. Maple syrup urine disease
C. Reye’s syndrome
D. Megaloblastic anemia

Answer 182

A. Lesch-Nyhan syndrome

Rationale:

Lesch-Nyhan syndrome is an X-linked genetic disorder (seen only in males) caused by the complete deficiency of hypoxanthine-guanine phosphoribosyltransferase, an important enzyme in the biosynthesis of purines.

Question 183

184. During chemotherapy for leukemia, which of the following analytes would most likely be elevated in the blood?

A. Uric acid
B. Urea
C. Creatinine
D. Ammonia

Answer 183

A. Uric acid

Rationale:

An increase in serum uric acid levels may be seen during chemotherapy for leukemia. The cause of this is the accelerated breakdown of cell nuclei in response to the chemotherapy.

Other proliferative disorders that may respond similarly are lymphoma, multiple myeloma, and polycythemia. It is important that serum uric acid be monitored during chemotherapy to avoid nephrotoxicity.

Question 184

185. What is the IMMEDIATE PRECURSOR of bilirubin formation?

A. Mesobilirubinogen
B. Verdohemoglobin
C. Urobilinogen
D. Biliverdin

Answer 184

D. Biliverdin

Rationale:

It is biliverdin that is the immediate precursor of bilirubin formation. Mesobilirubinogen and urobilinogen represent intestinal breakdown products of bilirubin catabolism.

Question 185

186. To quantify serum bilirubin levels, it is necessary that bilirubin couples with diazotized sulfanilic acid to form what complex?

A. Verdobilirubin
B. Azobilirubin
C. Azobilirubinogen
D. Bilirubin glucuronide

Answer 185

B. Azobilirubin

Rationale:

Diazo reagent is a mixture of sulfanilic acid, sodium nitrite, and hydrochloric acid. The mixing of sodium nitrite with hydrochloric acid forms nitrous acid, which in turn reacts with sulfanilic acid to form a diazonium salt. This diazotized sulfanilic acid mixture, when mixed with solubilized bilirubin, forms a red azobilirubin complex.

Question 186

187. What enzyme catalyzes the conjugation of bilirubin?

A. Leucine aminopeptidase
B. Glucose-6-phosphate dehydrogenase
C. Uridine diphosphate glucuronyltransferase
D. Carbamoyl phosphate synthetase

Answer 186

C. Uridine diphosphate glucuronyltransferase

Rationale:

In order for the bilirubin-albumin complex to reach the parenchymal cells of the liver, the complex must be transported from the sinusoids to the sinusoidal microvilli and into the parenchymal cell. The microsomal fraction of the parenchymal cell is responsible for the conjugation of bilirubin. It is here that bilirubin reacts with uridine diphosphate glucuronate in the presence of the enzyme uridine diphosphate glucuronyltransferase to form bilirubin diglucuronide.

Question 187

188. What breakdown product of bilirubin metabolism is produced in the colon from the oxidation of urobilinogen by microorganisms?

A. Porphobilinogen
B. Urobilin
C. Stercobilinogen
D. Protoporphyrin

Answer 187

B. Urobilin

Rationale:

In the colon, a portion of the urobilinogen is oxidized by the action of microorganisms to urobilin, which is excreted in the feces as an orange-brown pigment.

Question 188

189. Which of the following functions as a transport protein for bilirubin in the blood?

A. Albumin
B. Alpha-globulin
C. Beta-globulin
D. Gamma-globulin

Answer 188

A. Albumin

Rationale:

In the colon, a portion of the urobilinogen is oxidized by the action of microorganisms to urobilin, which is excreted in the feces as an orange-brown pigment.

Question 189

190. What term is used to describe the accumulation of bilirubin in the skin?

A. Jaundice
B. Hemolysis
C. Cholestasis
D. Kernicterus

Answer 189

A. Jaundice

Rationale:

Jaundice may be caused by an increase in either the unconjugated or conjugated form of bilirubin. Such increases in bilirubin levels may be caused by prehepatic, hepatic, or posthepatic disorders.

Question 190

191. In the condition kernicterus, the abnormal accumulation of bilirubin occurs in what tissue?

A. Brain
B. Liver
C. Kidney
D. Blood

Answer 190

A. Brain

Rationale:

Kernicterus refers to the accumulation of bilirubin in brain tissue that occurs with elevated levels of unconjugated bilirubin. This condition is most commonly seen in newborns with hemolytic disease resulting from maternal-fetal Rh incompatibility. Newborns afflicted with kernicterus will exhibit severe neural symptoms.

Question 191

192. As a reduction product of bilirubin catabolism, this compound is partially reabsorbed from the intestine through the portal circulation for reexcretion by the liver. What is this compound?

A. Verdohemoglobin
B. Urobilinogen
C. Urobilin
D. Biliverdin

Answer 191

B. Urobilinogen

Rationale:

In the small intestine, urobilinogen is formed through the enzymatic reduction process of anaerobic bacteria on bilirubin.

Question 192

193. Which of the following factors will NOT adversely affect the accurate quantification of bilirubin in serum?

A. Lipemia
B. Hemolysis
C. Exposure to light
D. Specimen refrigeration

Answer 192

D. Specimen refrigeration

Rationale:

ilirubin will deteriorate when exposed to either white or UV light. This deterioration is also temperature sensitive. Thus, specimens for bilirubin analysis should be stored in the dark at refrigerator temperature until the assay can be performed.

Lipemia should be avoided, due to its interference with spectrophotometric analyses. Because hemoglobin reacts with diazo reagent, use of hemolyzed specimens should be avoided. Hemolysis will cause bilirubin results to be falsely low.

Question 193

194. Which bilirubin fraction is conjugated and covalently bound to albumin? Bishop

A. Alpha
B. Beta
C. Delta
D. Gamma

Answer 193

C. Delta

Rationale:

Four bilirubin fractions represented by Greek letters have been identified: unconjugated (alpha), monoconjugated (beta), diconjugated (gamma), and unconjugated bilirubin covalently bound to albumin (delta).

Delta-bilirubin is normally present in low concentration in the blood, and it is known to react directly with diazotized sulfanilic acid. Increased serum levels of delta-bilirubin are associated with liver-biliary disease.

According to Bishop: DELTA bilirubin is CONJUGATED bilirubin that is covalently bound to albumin.

Question 194

195. As the red blood cells disintegrate, hemoglobin is released and converted to the pigment bilirubin. Which organ is primarily responsible for this function?

A. Spleen
B. Kidneys
C. Intestines
D. Liver

Answer 194

A. Spleen

Rationale:

The cells of the reticuloendothelial system are responsible for the removal of old red blood cells from the peripheral circulation. As the red blood cells reach the end of their 120-day life span, the specialized cells mainly of the spleen phagocytize the aged cells and convert the released hemoglobin into the excretory pigment bilirubin.

Question 195

196. Which of the following does NOT accurately describe direct bilirubin?

A. Insoluble in water
B. Conjugated in the liver
C. Conjugated with glucuronic acid
D. Excreted in the urine of jaundiced patients

Answer 195

A. Insoluble in water

Rationale:

Direct bilirubin was so named because of its ability in the van den Bergh method to react directly with diazotized sulfanilic acid without the addition of alcohol. Such a direct reaction is possible because direct bilirubin is conjugated in the liver with glucuronic acid, thereby making it a polar, water-soluble compound. Because conjugated bilirubin is both water soluble and not protein bound, it may be filtered through the glomerulus and excreted in the urine of jaundiced patients.

Question 196

197. Excreted in the urine of jaundiced patients:

A. Conjugated bilirubin
B. Unconjugated bilirubin
C. Both of these
D. None of these

Answer 196

A. Conjugated bilirubin

Rationale:

Because conjugated bilirubin is both water soluble and not protein bound, it may be filtered through the glomerulus and excreted in the urine of jaundiced patients.

Question 197

198. Which of the following reagent systems contains the components sulfanilic acid, hydrochloric acid, and sodium nitrite?

A. Jaffe
B. Zimmerman
C. Diazo
D. Lowry

Answer 197

C. Diazo

Question 198

199. Indirect-reacting bilirubin may be quantified by reacting it initially in which reagent?

A. Dilute hydrochloric acid
B. Dilute sulfuric acid
C. Caffeine-sodium benzoate
D. Sodium hydroxide

Answer 198

C. Caffeine-sodium benzoate

Rationale:

Unlike direct bilirubin, indirect-reacting bilirubin is insoluble in deionized water and dilute hydrochloric acid. Indirect-reacting bilirubin must first be mixed with methanol or caffeine-sodium benzoate to solubilize it before proceeding with the diazo reaction.

Note:

EVELYN-MALLOY: methanol
JENDRASSIK-GROF: caffeine-sodium benzoate

Question 199

200. What condition is characterized by an elevation of total bilirubin primarily due to an increase in the CONJUGATED BILIRUBIN fraction?

A. Hemolyticjaundice
B. Neonatal jaundice
C. Crigler-Najjar syndrome
D. Obstructive jaundice

Answer 199

D. Obstructive jaundice

Rationale:

“Obstructive jaundice” is a term applied to conditions in which the common bile duct is obstructed because of gallstone formation, spasm, or neoplasm. Such an obstruction blocks the flow of bile from the gallbladder into the small intestine. This impedance of bile flow will result in a backflow of bile from the gallbladder into the sinusoids of the liver and ultimately into the peripheral circulation. Because the liver is not initially involved and the disorder is of posthepatic origin, the increased levels of bilirubin in the blood are caused by the backflow of conjugated bilirubin.

Question 200

201. Which of the following is characteristic of hemolytic jaundice?

A. Unconjugated serum bilirubin level increased
B. Urinary bilirubin level increased
C. Urinary urobilinogen level decreased
D. Fecal urobilin level decreased

Answer 200

A. Unconjugated serum bilirubin level increased

Rationale:

Hemolytic jaundice is also referred to as prehepatic jaundice. It is caused by excessive destruction of erythrocytes at a rate that exceeds the conjugating ability of the liver. As a result, increased levels of unconjugated bilirubin appear in the blood.

Question 201

202. What may be the cause of NEONATAL PHYSIOLOGICAL JAUNDICE?

A. Hemolytic episode caused by an ABO incompatibility
B. Stricture of the common bile duct
C. Hemolytic episode caused by an Rh incompatibility
D. Deficiency in the bilirubin conjugation enzyme system

Answer 201

D. Deficiency in the bilirubin conjugation enzyme system

Rationale:

The enzyme uridine diphosphate glucuronyltransferase catalyzes the conjugation of bilirubin with glucuronic acid. In newborns, especially premature infants, this liver enzyme system is not fully developed or functional. Because of this deficiency in the enzyme system, the concentration of unconjugated bilirubin rises in the blood, because only the conjugated form may be excreted through the bile and urine. The increased levels of unconjugated bilirubin will cause the infant to appear jaundiced.

Generally, this condition persists for only a short period because the enzyme system usually becomes functional within several days after birth.

Question 202

203. Which of the following disorders is characterized by an INABILITY TO TRANSPORT BILIRUBIN from the sinusoidal membrane into the hepatocyte?

A. Carcinoma of the common bile duct
B. Crigler-Najjar syndrome
C. Dubin-Johnson syndrome
D. Gilbert syndrome

Answer 202

D. Gilbert syndrome

Rationale:

Gilbert syndrome is a preconjugation transport disturbance. In this disorder the hepatic uptake of bilirubin is defective because the transportation of bilirubin from the sinusoidal membrane to the microsomal region is impaired.

Question 203

204. Which of the following characterizes Crigler-Najjar syndrome?

A. Inability to transport bilirubin from the sinusoidal membrane to the microsomal region
B. Deficiency of the enzyme system required for conjugation of bilirubin
C. Inability to transport bilirubin glucuronides to the bile canaliculi
D. Severe liver cell damage accompanied by necrosis

Answer 203

B. Deficiency of the enzyme system required for conjugation of bilirubin

Rationale:

Both Crigler-Najjar syndrome and neonatal jaundice, a physiological disorder, are due to a deficiency in the enzyme-conjugating system. With a deficiency in uridine diphosphate glucuronyltransferase, the liver is unable to conjugate bilirubin, and both of these conditions are characterized by increased levels of unconjugated bilirubin.

Unlike Crigler-Najjar syndrome, which is a hereditary disorder, neonatal physiological jaundice is a temporary situation that usually corrects itself within a few days after birth.

Question 204

205. Which of the following is NOT characteristic of Dubin-Johnson syndrome?

A. Impaired excretion of bilirubin into the bile
B. Hepatic uptake of bilirubin is normal
C. Inability to conjugate bilirubin
D. Increased level of bilirubin in urine

Answer 204

C. Inability to conjugate bilirubin

Rationale:

In Dubin-Johnson syndrome, the transport of conjugated (direct) bilirubin from the microsomal region to the bile canaliculi is impaired. In this rare familial disorder, plasma conjugated bilirubin levels are increased because of defective excretion of bilirubin in the bile. Because conjugated bilirubin is water soluble, increased amounts of bilirubin are found in the urine.

Question 205

206. Beta-gamma bridging effect:

A. Multiple myeloma
B. Hepatic cirrhosis
C. Nephrotic syndrome
D. Inflammation

Answer 205

B. Hepatic cirrhosis

Rationale:

● Gamma spike: multiple myeloma
● Beta-gamma bridging: hepatic cirrhosis
● α1 globulin flat curve: juvenile cirrhosis (AATdeficiency)
● Α2 globulin band spike: nephrotic syndrome
● Spikes in α1, α2 and β: inflammation

Question 206

207. Less than 80% liver damage:

A. Hepatitis
B. Cirrhosis

Answer 206

A. Hepatitis

Rationale:

● HEPATITIS: less than 80% liver damage
● High: AST, ALT, LD, ALP, bilirubin
● Normal: Total protein, albumin, ammonia

Question 207

208. 80% liver tissue damage:

A. Hepatitis
B. Cirrhosis

Answer 207

B. Cirrhosis

Rationale:

● CIRRHOSIS: 80% liver tissue damage
● Death of liver cells with regeneration leads to fibrosis, scarring and destruction of the normal liver architecture
● Low: Total protein, albumin
● High: Bilirubin, ammonia
● Normal to slightly high: ALP
● Normal: AST, ALT and LD

Question 208

209. Destruction of liver architecture:

A. Cirrhosis
B. Hepatitis
C. Bile duct obstruction
D. None of these

Answer 208

A. Cirrhosis

Rationale:

Cirrhosis is defined as destruction of the liver’s architecture.
The leading cause of this condition is alcohol abuse.

Question 209

210. Increased in hepatic jaundice:

A. B1 only
B. B2 only
C. B1 and B2
D. None of these

Answer 209

C. B1 and B2

Rationale:

Hemolytic jaundice: unconjugated bilirubin (B1)
Hepatic jaundice: unconjugated and conjugated bilirubin (B1 and B2)
Obstructive jaundice: conjugated bilirubin (B2)

Question 210

211. What does an increase in the serum enzyme levels indicate?

A. Decreased enzyme catabolism
B. Accelerated enzyme production
C. Tissue damage and necrosis
D. Increased glomerular filtration rate

Answer 210

C. Tissue damage and necrosis

Rationale:

The majority of serum enzymes that are of interest clinically are of intracellular origin. These enzymes function intracellularly, with only small amounts found in serum as a result of normal cellular turnover. Increased serum levels are due to tissue damage and necrosis, where the cells disintegrate and leak their contents into the blood. Thus, elevated serum levels of intracellular enzymes are used diagnostically to assess tissue damage.

Question 211

212. When measuring enzyme activity, if the instrument is operating 5°C lower than the temperature prescribed for the method, how will the results be affected?

A. Lower than expected
B. Higher than expected
C. Varied, showing no particular pattern
D. All will be clinically abnormal.

Answer 211

A. Lower than expected

Rationale:

Factors that affect enzyme assays include temperature, pH, substrate concentration, and time of incubation. For each clinically important enzyme, the optimum temperature and pH for its specific reaction are known. When lower than optimum temperature or pH is employed, the measured enzyme activity will be lower than the expected activity value. As temperature increases, the rate of the reaction increases.

Question 212

213. The properties of enzymes are correctly described by which of the following statements?

A. Enzymes are stable proteins.
B. Enzymes are protein catalysts of biological origin.
C. Enzymes affect the rate of a chemical reaction by raising the activation energy needed for the reaction to take place.
D. Enzyme activity is not altered by heat denaturation.

Answer 212

B. Enzymes are protein catalysts of biological origin.

Rationale:

Enzymes are protein in nature. Like all proteins, they may be denatured with a loss of activity as a result of several factors (e.g., heat, extreme pH, mechanical agitation, strong acids, and organic solvents). Enzymes act as catalysts for the many chemical reactions of the body. Enzymes increase the rate of a specific chemical reaction by lowering the activation energy needed for the reaction to proceed.

Question 213

214. The shape of the key (substrate) must fit into the lock (enzyme):

A. Induced-fit theory by Emil Fischer
B. Induced-fit theory by Daniel Koshland
C. Lock-and-key theory by Emil Fischer
D. Lock-and-key theory by Daniel Koshland

Answer 213

C. Lock-and-key theory by Emil Fischer

Rationale:

LOCK-AND-KEY (EMIL FISCHER)
● The shape of the key (substrate) must fit into the lock (enzyme)

INDUCED-FIT (DANIEL KOSHLAND)
● Substrate binding to the active site of the enzyme

Question 214

215. The reaction rate is directly proportional to substrate concentration:

A. First-order kinetics
B. Zero-order kinetics

Answer 214

A. First-order kinetics

Rationale:

In 1913, Michaelis and Menten hypothesized the role of substrate concentration in formation of the enzyme–substrate (ES) complex. According to their hypothesis, the substrate readily binds to free enzyme at a low-substrate concentration. With the amount of enzyme exceeding the amount of substrate, the reaction rate steadily increases as more substrate is added. The reaction is following first-order kinetics because the reaction rate is directly proportional to substrate concentration.

Eventually, however, the substrate concentration is high enough to saturate all available enzyme, and the reaction velocity reaches its maximum. When product is formed, the resultant free enzyme immediately combines with excess free substrate. The reaction is in zero-order kinetics, and the reaction rate depends only on enzyme concentration.

Question 215

216. The reaction rate depends only on enzyme concentration:

A. First-order kinetics
B. Zero-order kinetics

Answer 215

B. Zero-order kinetics

Question 216

217. Multiple measurements, usually of absorbance change, are made during the reaction, either at specific time intervals (usually every 30 or 60 seconds) or continuously by a continuous- recording spectrophotometer:

A. Fixed-time assay
B. Kinetic assay

Answer 216

B. Kinetic assay

Rationale:

One of two general methods may be used to measure the extent of an enzymatic reaction: (1) fixed-time and (2) continuous-monitoring or kinetic assay.

1. In the fixed time method, the reactants are combined, the reaction proceeds for a designated time, the reaction is stopped (usually by inactivating the enzyme with a weak acid), and a measurement is made of the amount of reaction that has occurred. The reaction is assumed to be linear over the reaction time; the larger the reaction, the more enzyme is present.
2. In continuous-monitoring or kinetic assays, multiple measurements, usually of absorbance change, are made during the reaction, either at specific time intervals (usually every 30 or 60 seconds) or continuously by a continuous- recording spectrophotometer.

Question 217

218. An organic cofactor, such as nicotinamide adenine dinucleotide (NAD):

A. Activator
B. Coenzyme
C. Proenzyme
D. Zymogen

Answer 217

B. Coenzyme

Rationale:

A nonprotein molecule, called a cofactor, may be necessary for enzyme activity. Inorganic cofactors, such as chloride or magnesium ions, are called activators. A coenzyme is an organic cofactor, such as nicotinamide adenine dinucleotide (NAD).

When bound tightly to the enzyme, the coenzyme is called a prosthetic group. The enzyme portion (apoenzyme), with its respective coenzyme, forms a complete and active system, a holoenzyme.

Question 218

219. Inorganic cofactors, such as chloride or magnesium ions:

A. Activator
B. Coenzyme
C. Proenzyme
D. Zymogen

Answer 218

A. Activator

Question 219

220. Enzymes that catalyze the transfer of groups between compounds are classified as belonging to which enzyme class?

A. Hydrolases
B. Lyases
C. Oxidoreductases
D. Transferases

Answer 219

D. Transferases

Rationale:

There are six major classes of enzymes. The International Commission of Enzymes of the International Union of Biochemistry has categorized all enzymes into one of these classes: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. Transferases are enzymes that catalyze the transfer of groups, such as amino and phosphate groups, between compounds. Transferases frequently need coenzymes, such as pyridoxal-5’-phosphate (P-5-P), for the amino transfer reactions. Aspartate and alanine aminotransferases, creatine kinase, and gamma-glutamyltransferase are typical examples.

Question 220

221. Which of the following enzymes does not belong to the class of enzymes known as the hydrolases?

A. Alkaline phosphatase
B. Aldolase
C. Amylase
D. Lipase

Answer 220

B. Aldolase

Rationale:

Hydrolases are enzymes that split molecules with the addition of water—for example, amylase, lipase, alkaline phosphatase, acid phosphatase,

5’-nucleotidase, and trypsin. They do not usually require coenzymes but often need activators.

Aldolase and carbonic anhydrase are examples of the class of enzymes known as the lyases. Lyases are enzymes that split molecules between carbon-to-carbon bonds without the addition of water. The resulting products usually contain carbon double bonds.

Question 221

222. To what class of enzymes does lactate dehydrogenase belong?

A. Isomerases
B. Ligases
C. Oxidoreductases
D. Transferases

Answer 221

C. Oxidoreductases

Question 222

223. Catalyze the joining of two substrate molecules, coupled with breaking of the pyrophosphate bond in adenosine triphosphate (ATP) or a similar compound:

A. Oxidoreductases
B. Hydrolases
C. Lyases
D. Ligases

Answer 222

D. Ligases

Rationale:

In addition to naming enzymes, the IUB system identifies each enzyme by an EC numerical code containing four digits separated by decimal points. The first digit places the enzyme in one of the following six classes:

1. Oxidoreductases. Catalyze an oxidation–reduction reaction between two substrates
2. Transferases. Catalyze the transfer of a group other than hydrogen from one substrate to another
3. Hydrolases. Catalyze hydrolysis of various bonds
4. Lyases. Catalyze removal of groups from substrates without hydrolysis; the product contains double bonds
5. Isomerases. Catalyze the interconversion of geometric, optical, or positional isomers
6. Ligases. Catalyze the joining of two substrate molecules, coupled with breaking of the pyrophosphate bond in adenosine triphosphate (ATP) or a similar compound

Question 223

224. Enzymes catalyze physiologic reactions by ____ the activation energy level that the reactants (substrates) must reach for the reaction to occur.

A. Decreasing the activation energy
B. Increasing the activation energy

Answer 223

A. Decreasing the activation energy

Question 224

225. The highest levels of total LD are seen in:

A. AMI and pulmonary infarction
B. Pernicious anemia and hemolytic disorders
C. Skeletal muscle disorders
D. Viral hepatitis and cirrhosis

Answer 224

B. Pernicious anemia and hemolytic disorders

Question 225

226. Most labile LD isoenzyme:

A. LD-1
B. LD-2
C. LD-3
D. LD-4
E. LD-5

Answer 225

E. LD-5

Rationale:

LD-5 is the most labile isoenzyme. Loss of activity occurs more quickly at 4°C than at 25°C. Serum samples for LD isoenzyme analysis should be stored at 25°C and analyzed within 24 hours of collection.

Question 226

227. The highest elevations of ALP activity occur in:

A. Biliary tract obstruction
B. Hepatitis
C. Osteomalacia
D. Paget’s disease

Answer 226

D. Paget’s disease

Rationale:

Elevated ALP levels may be observed in various bone disorders. Perhaps the highest elevations of ALP activity occur in Paget’s disease (osteitis deformans). Other bone disorders include osteomalacia, rickets, hyperparathyroidism, and osteogenic sarcoma.

Question 227

228. Which of the following disorders is NOT associated with an elevation of serum creatine kinase?

A. Duchenne-type progressive muscular dystrophy
B. Myocardial infarction
C. Cerebrovascular accidents (stroke)
D. Bone disease
E. Intramuscular injection

Answer 227

D. Bone disease

Rationale:

Increased serum creatine kinase (CK), formerly called creatine phosphokinase (CPK), values are caused primarily by lesions of cardiac muscle, skeletal muscle, or brain tissue. CK increases in the early stages of Duchenne-type progressive muscular dystrophy. Assays of total CK and CK isoenzymes are commonly used in the diagnosis of myocardial infarction. Hypothyroidism causes a moderate increase in CK values. Elevation of this enzyme also occurs after vigorous muscular activity, in cases of cerebrovascular accidents (stroke), and after repeated intramuscular injections.

Question 228

229. To aid in the diagnosis of skeletal muscle disease, which of the following serum enzyme measurements would be of most use?

A. Creatine kinase
B. Alkaline phosphatase
C. Aspartate aminotransferase
D. Alanine aminotransferase

Answer 228

A. Creatine kinase

Rationale:

To aid in the diagnosis of skeletal muscle disease, measurement of creatine kinase would be most useful. CK yields the most reliable information when skeletal muscle disease is suspected.

Other enzymes that are also useful to measure are aspartate aminotransferase and lactate dehydrogenase. Both of these enzymes will be moderately elevated, whereas CK is significantly increased.

Question 229

230. When an AMI occurs, in what order (list first to last) will the enzymes aspartate aminotransferase (AST), creatine kinase(CK), and lactate dehydrogenase (LD) become elevated in the serum?

A. AST, LD, CK
B. CK, LD, AST
C. CK, AST, LD
D. LD, CK, AST

Answer 229

C. CK, AST, LD

Rationale:

When an AMI occurs, CK is the first enzyme to become elevated in the blood, rising within 4 to 6 hours following chest pain. AST exhibits a rise in the serum level within 6 to 8 hours. LD shows an increase in 8 to 12 hours following infarction.

Measurement of these three enzymes to assess acute myocardial infarction has been replaced by cardiac troponin, myoglobin, and CK-MB.

Question 230

231. Pathological levels are DECREASED from the normal values, sometimes as much as 80 to 90%:

A. Acid phosphatase
B. Alkaline phosphatase
C. Cholinesterase
D. Creatine kinase

Answer 230

C. Cholinesterase

Rationale:

Normal serum levels of cholinesterase are quite high, reflecting its continual synthesis and release by the liver. Decreased values are considered abnormal.

Question 231

232. The smallest enzyme:

A. Amylase
B. Lipase
C. CK
D. GGT

Answer 231

A. Amylase

Rationale:

AMYLASE is the smallest enzyme, with a molecular weight of 50,000 to 55,000 Da. Because of its small size, it is readily filtered by the renal glomerulus and also appears in the urine.

Question 232

233. All of the following are macroenzymes, except:

A. ACP and ALP
B. ALT and AST
C. CK
D. GGT
E. G6PD

Answer 232

E. G6PD

Rationale:

Macroenzymes are high-molecular-mass forms of the serum enzymes (ACP, ALP, ALT, AMY, AST, CK, GGT, LD, and LPS) that can be bound to either an immunoglobulin (macroenzyme type 1) or a nonimmunoglobulin substance (macroenzyme type 2).

Macroenzymes are usually found in patients who have an unexplained persistent increase of enzyme concentrations in serum. The presence of macroenzymes can also increase with increasing age.

Question 233

234. Which of the following tumor markers is used to monitor persons with breast cancer for recurrence of disease?

A. Cathepsin-D
B. CA-15-3
C. Retinoblastoma gene
D. Estrogen receptor (ER)

Answer 233

B. CA-15-3

Question 234

235. Which tumor marker is used to determine trastuzumab (Herceptin) therapy for breast cancer?

A. PR
B. CEA
C. HER-2/neu
D. Myc

Answer 234

C. HER-2/neu

Question 235

236. Which of the following is the best analyte to monitor for recurrence of ovarian cancer?

A. CA 15-3
B. CA 19-9
C. CA-125
D. CEA

Answer 235

C. CA-125

Question 236

237. Which tumor marker is associated with cancer of the urinary bladder?

A. CA-19-9
B. CA-72-4
C. Nuclear matrix protein
D. Cathepsin-D

Answer 236

C. Nuclear matrix protein

Question 237

238. Which type of cancer is associated with the highest level of AFP?

A. Hepatoma
B. Ovarian cancer
C. Testicular cancer
D. Breast cancer

Answer 237

A. Hepatoma

Question 238

239. Major cation, or positively charged particle, and is found in the highest concentration in extracellular fluid:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 238

D. Sodium

Question 239

240. Major intracellular cation:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 239

C. Potassium

Question 240

241. Integral part of the transmission of nerve impulses:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 240

C. Potassium

Rationale:

As the primary intracellular cation, potassium is an integral part of the transmission of nerve impulses. Movement of potassium across the nerve tissue membrane permits the neural signal to move down the nerve fiber. Potassium also seems to be involved in synaptic processes, where the impulse “jumps” from one nerve fiber to another.

Question 241

242. It is the major anion that counterbalances the major cation, sodium.

A. Bicarbonate
B. Calcium
C. Chloride
D. Potassium

Answer 241

C. Chloride

Question 242

243. Two main functions in the body: (1) determining the osmotic pressure, which controls the distribution of water among cells, plasma, and interstitial fluid, and (2) maintaining electrical neutrality.

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 242

B. Chloride

Question 243

244. Second most abundant anion in the extracellular fluid; major component of the blood buffering system, accounts for 90% of total blood carbon dioxide, and maintains charge neutrality in the cell:

A. Bicarbonate
B. Chloride
C. Magnesium
D. Potassium

Answer 243

A. Bicarbonate

Question 244

245. Fourth most abundant cation in the body and second most abundant intracellular ion:

A. Calcium
B. Magnesium
C. Potassium
D. Sodium

Answer 244

B. Magnesium

Question 245

246. Electrolyte(s) essential for blood coagulation:

A. Calcium
B. Calcium and magnesium
C. Calcium, magnesium and potassium
D. Bicarbonate, potassium and chloride

Answer 245

B. Calcium and magnesium

Rationale:

Electrolytes are an essential component in numerous processes, including:

1. Volume and osmotic regulation (sodium [Na+], chloride [Cl−], potassium [K+])
2. Myocardial rhythm and contractility (K+, magnesium [Mg2+], calcium [Ca2+])
3. Cofactors in enzyme activation (e.g., Mg2+, Ca2+, zinc [Zn2+])
4. Regulation of adenosine triphosphatase (ATPase) ion pumps (Mg2+)
5. Acid–base balance (bicarbonate HCO3−, K+, Cl−)
6. Blood coagulation (Ca2+, Mg2+)
7. Neuromuscular excitability (K+, Ca2+, Mg2+)
8. Production and use of ATP from glucose (e.g., Mg2+, phosphate PO4−)

Question 246

247. Electrolyte(s) essential for acid-base balance:

A. Bicarbonate and calcium
B. Bicarbonate and chloride
C. Bicarbonate, potassium and chloride
D. Calcium and magnesium

Answer 246

C. Bicarbonate, potassium and chloride

Question 247

248. The presence of only slightly visible hemolysis will significantly increase the serum level of which of the following electrolytes?

A. Sodium
B. Potassium
C. Chloride
D. Bicarbonate

Answer 247

B. Potassium

Rationale:

Hemolysis of blood specimens because of physiological factors is often difficult to differentiate from hemolysis produced by the blood collection itself. In either case, the concentration of potassium will be increased in the serum because of the release of the very high level of intracellular potassium from the erythrocytes into the plasma.

When hemolysis is present, the serum concentrations of sodium, bicarbonate, chloride, and calcium will be decreased because their concentrations are lower in erythrocytes than in plasma.

Question 248

249. Most abundant cation in the ECF, representing 90% of all extracellular cations, and largely determines the osmolality of the plasma:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 248

D. Sodium

Question 249

250. Hyponatremia is defined as a serum/plasma level:

A. Less than 165 mmol/L
B. Less than 145 mmol/L
C. Less than 140 mmol/L
D. Less than 135 mmol/L

Answer 249

D. Less than 135 mmol/L

Rationale:

Hyponatremia is defined as a serum/plasma level less than 135 mmol/L.

Hyponatremia is one of the most common electrolyte disorders in hospitalized and nonhospitalized patients.

Levels below 130 mmol/L are clinically significant. Hyponatremia can be assessed by the cause for the decrease or with the osmolality level.

Question 250

251. Hyponatremia due to increased water retention, except:

A. Congestive heart failue
B. Hepatic cirrhosis
C. Diuretic use
D. Renal failure

Answer 250

C. Diuretic use

Question 251

252. Hyponatremia can also be classified according to:

A. Chloride
B. Glucose
C. Plasma/serum osmolality
D. Urine osmolality

Answer 251

C. Plasma/serum osmolality

Rationale:

Hyponatremia can also be classified according to plasma/serum osmolality.

Because Na+ is a major contributor to osmolality, both levels can assist in identifying the cause of hyponatremia.

There are three categories of hyponatremia—low osmolality, normal osmolality, or high osmolality. Most instances of hyponatremia occur with decreased osmolality.

Question 252

253. Can occur when sodium is measured using indirect ion-selective electrodes (ISEs) in a patient who is HYPERPROTEINEMIC or HYPERLIPIDEMIC.

A. Hyponatremia
B. Hypernatremia
C. Pseudohyponatremia
D. Pseudohypernatremia

Answer 252

C. Pseudohyponatremia

Rationale:

Pseudohyponatremia can occur when Na+ is measured using indirect ion-selective electrodes (ISEs) in a patient who is hyperproteinemic or hyperlipidemic. An indirect ISE dilutes the sample prior to analysis and as a result of plasma/serum water displacement; the ion levels are falsely decreased.

Question 253

254. The measurement of __________ is necessary to evaluate the cause of hypernatremia.

A. Chloride
B. Glucose
C. Plasma/serum osmolality
D. Urine osmolality

Answer 253

D. Urine osmolality

Rationale:

The measurement of urine osmolality is necessary to evaluate the cause of hypernatremia. With renal loss of water, the urine osmolality is low or normal. With extrarenal fluid losses, the urine osmolality is increased.

Question 254

255. With increased water loss, burn patients are most likely to also experience:

A. Hypernatremia
B. Hyponatremia
C. Hypomagnesemia
D. Hypoosmolality

Answer 254

A. Hypernatremia

Rationale:

Any condition that increases water loss, such as fever, burns, diarrhea, or exposure to heat, will increase the likelihood of developing hypernatremia.

Question 255

256. Major intracellular cation in the body:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 255

C. Potassium

Rationale:

Potassium (K+) is the major intracellular cation in the body, with a concentration 20 times greater inside the cells than outside.

Many cellular functions require that the body maintain a low ECF concentration of K+ ions. As a result, only 2% of the body’s total K+ circulates in the plasma. Functions of K+ in the body include regulation of neuromuscular excitability, contraction of the heart, ICF volume, and H+ concentration.

Question 256

257. Hypokalemia due to gastrointestinal loss:

A. Acute leukemia
B. Alkalosis
C. Hypomagnesemia
D. Vomiting

Answer 256

D. Vomiting

Question 257

258. All are associated with hyperkalemia, except:

A. Acidosis
B. Alkalosis
C. Oral or intravenous potassium therapy
D. Diuretics

Answer 257

B. Alkalosis

Question 258

259. Major extracellular anion:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 258

B. Chloride

Rationale:

Chloride (Cl−) is the major extracellular anion.

It is involved in maintaining osmolality, blood volume, and electric neutrality.

In most processes, Cl− shifts secondarily to a movement of Na+ or HCO3 −.

Question 259

260. Which of the following disorders is characterized by increased production of chloride in sweat?

A. Multiple myeloma
B. Hypoparathyroidism
C. Cystic fibrosis
D. Wilson disease

Answer 259

C. Cystic fibrosis

Rationale:

Measuring the concentration of chloride in sweat is a commonly used diagnostic procedure for determining the disorder of cystic fibrosis (CF). The majority of patients with CF will present with increased concentrations of sodium and chloride in their sweat.

Question 260

261. The second most abundant anion in the ECF:

A. Bicarbonate
B. Chloride
C. Potassium
D. Sodium

Answer 260

A. Bicarbonate

Rationale:

Bicarbonate is the second most abundant anion in the ECF. Total CO2 comprises the bicarbonate ion (HCO3−), H2CO3, and dissolved CO2, with HCO3− accounting for more than 90% of the total CO2 at physiologic pH.

Because HCO3− composes the largest fraction of total CO2, total CO2 measurement is indicative of HCO3− measurement.

Question 261

262. The fourth most abundant cation in the body and second most abundant intracellular ion:

A. Bicarbonate
B. Calcium
C. Chloride
D. Magnesium

Answer 261

D. Magnesium

Rationale:

Magnesium (Mg2+) is the fourth most abundant cation in the body and second most abundant intracellular ion. The average human body (70 kg) contains 1 mol (24 g) of Mg2+. Approximately 53% of Mg2+ in the body is found in bone, 46% in muscle and other organs and soft tissue, and less than 1% is present in serum and RBCs.

Question 262

263. Most frequently observed in hospitalized individuals in intensive care units (ICUs) or those receiving diuretic therapy or digitalis therapy:

A. Hypomagnesemia
B. Hypermagnesemia
C. Hypocalcemia
D. Hypercalcemia

Answer 262

A. Hypomagnesemia

Rationale:

Hypomagnesemia is most frequently observed in hospitalized individuals in intensive care units (ICUs) or those receiving diuretic therapy or digitalis therapy.

These patients most likely have an overall tissue depletion of Mg2+ as a result of severe illness or loss, which leads to low serum levels. Hypomagnesemia is rare in nonhospitalized individuals.

Question 263

264. Regulate(s) calcium:

A. Vitamin D
B. Vitamin D and calcitonin
C. Parathyroid hormone and calcitonin
D. Parathyroid hormone, vitamin D and calcitonin

Answer 263

D. Parathyroid hormone, vitamin D and calcitonin

Question 264

265. Of the total serum calcium, free ionized calcium normally represents approximately what percent?

A. 10
B. 40
C. 50
D. 90

Answer 264

C. 50

Question 265

266. Which of the following reagents is used in a colorimetric method to quantify the concentration of serum calcium?

A. Cresolphthalein complexone
B. Lanthanum
C. Malachite green
D. Amino-naphthol-sulfonic acid

Answer 265

A. Cresolphthalein complexone

Question 266

267. Which of the following reagents is used to determine the concentration of serum inorganic phosphate?

A. Ehrlich’s reagent
B. Ammonium molybdate
C. 8-Hydroxyquinoline
D. Bathophenanthroline

Answer 266

B. Ammonium molybdate

Rationale:

Serum inorganic phosphate concentrations are determined most commonly by reacting with ammonium molybdate reagent. The molybdenum-phosphate complexes can be quantified at 340 nm. Alternately, treatment of the phosphomolybdate compound formed with a reducing agent leads to the formation of molybdenum blue, which can be measured spectrophotometrically.

Question 267

268. PLEASE CHECK FIVE (5) BOXES: Elevated anion gap.

o Hypercalcemia
o Hypernatremia
o Hypoalbuminemia
o Ketoacidosis
o Lactic acidosis
o Methanol, ethanol, ethylene glycol poisoning
o Uremia/renal failure

Answer 267

o Hypernatremia
o Ketoacidosis
o Lactic acidosis
o Methanol, ethanol, ethylene glycol poisoning
o Uremia/renal failure

Question 268

269. PLEASE CHECK TWO (2) BOXES: Low anion gap.

o Hypercalcemia
o Hypernatremia
o Hypoalbuminemia
o Ketoacidosis
o Lactic acidosis
o Methanol, ethanol, ethylene glycol poisoning
o Uremia/renal failure

Answer 268

o Hypercalcemia
o Hypoalbuminemia

Question 269

270. The sample of choice for measuring blood osmolality is:

A. Serum
B. Plasma
C. Whole blood
D. Serum or plasma may be used

Answer 269

A. Serum

Rationale:

Osmolality may be measured in serum or urine. Major electrolyte concentrations, mainly sodium, chloride, and bicarbonate, provide the largest contribution to the osmolality value of serum.

Plasma use is not recommended because osmotically active substances may be introduced into the specimen from the anticoagulant.

Question 270

271. Of the total serum osmolality, sodium, chloride, and bicarbonate ions normally contribute approximately what percent?

A. 8
B. 45
C. 75
D. 92

Answer 270

D. 92

Rationale:

For monovalent cations or anions the contribution to osmolality is approximately 92%.

Other serum electrolytes, serum proteins, glucose, and urea contribute to the remaining 8%.

Question 271

272. Which electrolyte level best correlates with plasma osmolality?

A. Sodium
B. Chloride
C. Bicarbonate
D. Calcium

Answer 271

A. Sodium

Question 272

273. Which formula is most accurate in predicting plasma osmolality?

A. Na + 2(Cl) + BUN + glucose
B. 2(Na) + 2(Cl) + glucose + urea
C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8)
D. Na + Cl + K + HCO3

Answer 272

C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8)

Question 273

274. What is the primary storage form of iron?

A. Apotransferrin
B. Myoglobin
C. Ferritin
D. Hemosiderin

Answer 273

C. Ferritin

Rationale:

In adults the total body iron content averages 3-4 g. The majority of this iron is found in the active pool as an essential constituent of hemoglobin, with a much lesser amount being an integral component of myoglobin and a number of enzymes.

Approximately 25% of the body iron is found in inactive storage forms. The major storage form of iron is ferritin, with a lesser amount being stored as hemosiderin.

Question 274

275. The anticoagulant of choice for arterial blood gas measurements is ______ in the ______ state.

A. Lithium heparin; dry
B. EDTA; dry
C. Potassium oxalate; liquid
D. Sodium citrate; dry

Answer 274

A. Lithium heparin; dry

Rationale:

Evacuated collection tubes are not appropriate for blood gases. While both dry (lyophilized) and liquid heparin are acceptable anticoagulants, the liquid form is not recommended because excessive amounts can dilute the sample and possibly alter the sample due to equilibration with room air.

Question 275

276. If a blood gas specimen is left exposed to air, which of the following changes will occur?

A. pO2 and pH increase; pCO2 decreases
B. pO2 and pH decrease; pCO2 increases
C. pO2 increases; pH and pCO2 decrease
D. pO2 decreases; pH and pCO2 increase

Answer 275

A. pO2 and pH increase; pCO2 decreases

Rationale:

Note:

OPEN TUBE (ENTRY OF OXYGEN)

⬆️ Increased pO2
⬇️ Deceased pCO2 (H2CO3)
⬆️ Increased pH (ALKALINE)

CLOSED TUBE (OXYGEN UTILIZED BY CELLS)

⬇️ Decreased pO2
⬆️ Increased pCO2 (H2CO3)
⬇️ Decreased pH (ACIDIC)

Question 276

277. How would blood gas parameters change if a sealed specimen is left at room temperature for 2 or more hours?

A. pO2 increases, pCO2 increases, pH increases
B. pO2 decreases, pCO2 decreases, pH decreases
C. pO2 decreases, pCO2 increases, pH decreases
D. pO2 increases, pCO2 increases, pH decreases

Answer 276

C. pO2 decreases, pCO2 increases, pH decreases

Question 277

278. Which is the most predominant buffer system in the body?

A. Bicarbonate/carbonic acid
B. Acetate/acetic acid
C. Phosphate/phosphorous acid
D. Hemoglobin

Answer 277

A. Bicarbonate/carbonic acid

Rationale:

Because of its high concentration in blood, the bicarbonate/carbonic acid pair is the most important buffer system in the blood. This buffer system is also effective in the lungs and in the kidneys in helping to regulate body pH.

The other buffers that also function to help maintain body pH are the phosphate, protein, and hemoglobin buffer systems.

Question 278

279. To maintain a pH of 7.4 in plasma, it is necessary to maintain a:

A. 10:1 ratio of bicarbonate to carbonic acid
B. 20:1 ratio of bicarbonate to carbonic acid
C. 1:20 ratio of bicarbonate to carbonic acid
D. 20:1 ratio of carbonic acid to bicarbonate

Answer 278

B. 20:1 ratio of bicarbonate to carbonic acid

Question 279

280. The normal ratio of CARBONIC ACID TO BICARBONATE in arterial blood is:

A. 1:20
B. 7.4:6.1
C. 0.003:1.39
D. 20:1

Answer 279

A. 1:20

Question 280

281. Driving force of the bicarbonate buffer system:

A. Bicarbonate
B. Carbon dioxide
C. Chloride
D. Hydrogen

Answer 280

B. Carbon dioxide

Question 281

282. Fever:

A. Will decrease pO2 by 3%
B. Will increase pO2 by 3%
C. Will decrease pO2 by 7%
D. Will increase pO2 by 7%

Answer 281

C. Will decrease pO2 by 7%

Question 282

283. Fever:

A. Will decrease pCO2 by 3%
B. Will increase pCO2 by 3%
C. Will decrease pCO2 by 7%
D. Will increase pCO2 by 7%

Answer 282

B. Will increase pCO2 by 3%

Question 283

284. The role of the lungs and kidneys in maintaining pH is depicted with the Henderson-Hasselbalch equation. The numerator denotes:

A. Kidney function
B. Lung function

Answer 283

A. Kidney function

Question 284

285. The role of the lungs and kidneys in maintaining pH is depicted with the Henderson-Hasselbalch equation. The denominator denotes:

A. Kidney function
B. Lung function

Answer 284

B. Lung function

Question 285

286. In the plasma, an excess in the concentration of bicarbonate without a change in pCO2 from normal will result in what physiological state?

A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis

Answer 285

D. Metabolic alkalosis

Rationale:

An excess of bicarbonate without a change in pCO2 will increase the ratio of bicarbonate to carbonic acid. Therefore, the pH will increase; that is, the plasma becomes more alkaline.

Question 286

287. Which set of results is consistent with uncompensated respiratory alkalosis?

A. pH 7.70 HCO3- 30 mmol/L, pCO2 25 mm Hg
B. pH 7.66 HCO3- 22 mmol/L pCO2 20 mm Hg
C. pH 7.46 HCO3- 38 mmol/L pCO2 55 mm Hg
D. pH 7.36 HCO3- 22 mmol/L pCO2 38 mm Hg

Answer 286

B. pH 7.66 HCO3- 22 mmol/L pCO2 20 mm Hg

Rationale:

TIPS FOR EVALUATING ACID-BASE DISORDERS

1. Look at the pH: determine if acidosis or alkalosis
2. Compare pCO2 and HCO3-

A. pCO2 going opposite to pH – RESPIRATORY

Abnormal pCO2 respiratory [↓pH ↑pCO2 respiratory acidosis] [↑pH ↓pCO2 respiratory alkalosis]

B. HCO3- going same direction as pH - METABOLIC

Abnormal HCO3- metabolic [↓pH ↓HCO3- metabolic acidosis] [↑ pH ↑ HCO3- metabolic alkalosis]

3. If pH is normal, full compensation occurred
4. If main compensatory mechanism kicked in, but pH still out of normal range, partial compensation has occurred

Question 287

288. Which set of results is consistent with uncompensated metabolic acidosis?

A. pH 7.25 HCO3- 15 mmol/L pCO2 37 mm Hg
B. pH 7.30 HCO3- 16 mmol/L pCO2 28 mm Hg
C. pH 7.45 HCO3- 22 mmol/L pCO2 40 mm Hg
D. pH 7.40 HCO3- 25 mmol/L pCO2 40 mm Hg

Answer 287

A. pH 7.25 HCO3- 15 mmol/L pCO2 37 mm Hg

Question 288

289. A patient’s blood gas results are: pH = 7.50; pCO2 = 55 mm Hg; and HCO3– = 40 mmol/L. These results indicate:

A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis

Answer 288

D. Metabolic alkalosis

Rationale:

A pH above 7.45 corresponds with alkalosis. Both bicarbonate and pCO2 are elevated. Bicarbonate is the conjugate base and is under metabolic (renal) control, while pCO2 is an acid and is under respiratory control. Increased bicarbonate (but not increased CO2) results in alkalosis; therefore, the classification is metabolic alkalosis, partially compensated by increased pCO2.

Question 289

290. The following conditions are all causes of alkalosis. Which condition is associated with respiratory alkalosis?

A. Anxiety
B. Hypovolemia
C. Hyperaldosteronism
D. Severe diarrhea

Answer 289

A. Anxiety

Question 290

291. Which of the following blood gas parameters are measured directly by the blood gas analyzer electrochemically as opposed to being calculated by the instrument?

A. pH, HCO3- and total CO2
B. pCO2, HCO3- and pO2
C. pH, pCO2 and pO2
D. pO2, HCO3- and total CO2

Answer 290

B. pCO2, HCO3- and pO2

Rationale:

pH, pCO2, and pO2 are measured directly from the specimen by utilizing electrodes. The pH and PCO2 electrodes are potentiometric where the voltage produced across a semipermeable membrane to hydrogen ions or CO2 gas is proportional to the “activity” of those ions in the patient’s sample. Activity is measured in voltage whose value can be presented in terms of concentration. pO2 is measured similarly, but using an amperometric electrode.

Note:

pH and pCO2 = POTENTIOMETRY

pO2 = AMPEROMETRY

Question 291

292. A substance that can yield a hydrogen ion (H+) or hydronium ion when dissolved in water:

A. Acid
B. Base
C. Base excess
D. Buffer

Answer 291

A. Acid

Question 292

293. A substance that can yield hydroxyl ions (OH-):

A. Acid
B. Base
C. Base excess
D. Buffer

Answer 292

B. Base

Question 293

294. The combination of a weak acid or weak base and its salt, is a system that resists changes in pH:

A. Acid
B. Base
C. Base excess
D. Buffer

Answer 293

D. Buffer

Question 294

295. Mixed respiratory and nonrespiratory disorders _____ arise from more than one pathologic process.

A. Rarely
B. Occasionally
C. Frequently
D. Mostly

Answer 294

B. Occasionally

Rationale:

Mixed respiratory and nonrespiratory disorders occasionally arise from more than one pathologic process and represent the most serious of medical conditions as compensation for the primary disorder is failing.

Question 295

296. An emphysema patient suffering from fluid accumulation in the alveolar spaces is likely to be in what metabolic state?

A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis

Answer 295

A. Respiratory acidosis

Question 296

297. Master gland:

A. Adrenal cortex
B. Adrenal medulla
C. Pituitary gland
D. Thyroid gland

Answer 296

C. Pituitary gland

Question 297

298. Adenohypophysis:

A. Anterior pituitary gland
B. Posterior pituitary gland

Answer 297

A. Anterior pituitary gland

Question 298

299. Neurohypophysis

A. Anterior pituitary gland
B. Posterior pituitary gland

Answer 298

B. Posterior pituitary gland

Question 299

300. Tropic hormones:

o ACTH
o FSH
o GH
o LH
o Prolactin
o TSH

Answer 299

o ACTH
o FSH
o LH
o TSH

Question 300

301. Direct effectors:

A. ACTH
B. FSH
C. GH
D. LH
E. Prolactin
F. TSH

Answer 300

C. GH
E. Prolactin

Question 301

302. Also called somatotropin:

A. ACTH
B. GH
C. LH
D. Prolactin

Answer 301

B. GH

Rationale:

Growth hormone (GH), also called somatotropin, is structurally related to prolactin and human placental lactogen.

Question 302

303. The definitive suppression test to prove autonomous production of growth hormone is:

A. Oral glucose loading
B. Somatostatin infusion
C. Estrogen priming
D. Dexamethasone suppression

Answer 302

A. Oral glucose loading

Question 303

304. All of the following inhibit growth hormone secretion, except:

A. Glucose loading
B. Insulin deficiency
C. Thyroxine deficiency
D. Amino acids

Answer 303

D. Amino acids

Question 304

305. Prolactin is produced by the:

A. Anterior pituitary gland
B. Posterior pituitary gland
C. Adrenal cortex
D. Adrenal medulla

Answer 304

A. Anterior pituitary gland

Question 305

306. Diabetes insipidus:

A. Vasopressin deficiency
B. Vasopressin excess

Answer 305

A. Vasopressin deficiency

Question 306

307. Select the most appropriate single screening test for thyroid disease.

A. Free thyroxine index
B. Total T3 assay
C. Total T4
D. TSH assay

Answer 306

D. TSH assay

Rationale:

TSH is produced by the anterior pituitary in response to low levels of free T4 or T3. A normal TSH rules out thyroid disease. TSH is low in primary hyperthyroidism and high in primary hypothyroidism.

Question 307

308. The serum TSH level is almost absent in:

A. Primary hyperthyroidism
B. Primary hypothyroidism
C. Secondary hyperthyroidism
D. Euthyroid sick syndrome

Answer 307

A. Primary hyperthyroidism

Rationale:

In primary hyperthyroidism, the TSH will be within a range of 0–0.02 mU/mL, while in nonthyroid illnesses it will be 0.03 mU/mL or higher.

Question 308

309. A patient has an elevated serum T3 and free T4 and undetectable TSH. What is the most likely cause of these results?

A. Primary hyperthyroidism
B. Secondary hyperthyroidism
C. Euthyroid with increased thyroxine-binding proteins
D. Euthyroid sick syndrome

Answer 308

A. Primary hyperthyroidism

Question 309

310. Associated with neonatal hypothyroidism:

A. Cretinism
B. Growth retardation
C. Mental retardation
D. All of these

Answer 309

D. All of these

Question 310

311. Critical for sodium retention (volume), potassium, and acid–base homeostasis.

A. Aldosterone
B. Cortisol

Answer 310

A. Aldosterone

Rationale:

Zona glomerulosa (G-zone) cells (outer 10%) synthesize mineralocorticoids (aldosterone) critical for sodium retention (volume), potassium, and acid–base homeostasis. They have low cytoplasmic-to-nuclear ratios and small nuclei with dense chromatin with intermediate lipid inclusions.

Question 311

312. Critical to blood glucose homeostasis and blood pressure:

A. Aldosterone
B. Cortisol

Answer 311

B. Cortisol

Zona fasciculata (F-zone) cells (middle 75%) synthesize glucocorticoids, such as cortisol and cortisone critical to blood glucose homeostasis and blood pressure.

Question 312

313. First responders to stress by acting within seconds:

A. Aldosterone
B. Catecholamine
C. Cortisol
D. Estrogen

Answer 312

B. Catecholamine

Rationale:

Medullary catecholamine products serve as firstresponders to stress by acting within seconds (cortisol takes 20 min) to promote the fight-or-flight response, which increases cardiac output and blood pressure, diverts blood toward muscle and brain, and mobilizes fuel from storage.

Question 313

314. Which of the following is the mechanism causing Cushing’s disease?

A. Excess secretion of pituitary ACTH
B. Adrenal adenoma
C. Treatment with corticosteroids
D. Ectopic ACTH production by tumors

Answer 313

A. Excess secretion of pituitary ACTH

Rationale:

Cushing’s disease refers to adrenal hyperplasia resulting from misregulation of the hypothalamic–pituitary axis. It is usually caused by small pituitary adenomas. Cushing’s syndrome may be caused by Cushing’s disease, adrenal adenoma or carcinoma, ectopic ACTH-producing tumors, or excessive corticosteroid administration. The cause of Cushing’s syndrome can be differentiated using the ACTH and dexamethasone suppression tests.

Question 314

315. Which test is used to distinguish Cushing’s disease (pituitary Cushing’s) from Cushing’s syndrome caused by adrenal tumors?

A. Low-dose overnight dexamethasone suppression
B. Petrosal sinus sampling
C. Serum ACTH
D. Twenty-four–hour urinary free cortisol

Answer 314

C. Serum ACTH

Rationale:

Serum ACTH assays are very helpful in distinguishing the cause of Cushing’s syndrome. Patients with adrenal tumors have values approaching zero. Patients with ectopic ACTH tumors have values greater than 200 pg/dL. Fifty percent of patients with Cushing’s disease have high 8 a.m. ACTH levels (between 100–200 pg/dL). The high-dose dexamethasone suppression test is also used.

Question 315

316. Which is the most widely used screening test for Cushing’s syndrome?

A. Overnight low-dose dexamethasone suppression test
B. Corticotropin-releasing hormone stimulation test
C. Petrosal sinus sampling
D. Metyrapone stimulation test

Answer 315

A. Overnight low-dose dexamethasone suppression test

Question 316

317. The parent substance in the biosynthesis of androgens and estrogens is:

A. Cholesterol
B. Cortisol
C. Catecholamines
D. Progesterone

Answer 316

A. Cholesterol

Question 317

318. Select the main estrogen produced by the ovaries and used to evaluate ovarian function.

A. Estriol (E3)
B. Estradiol (E2)
C. Epiestriol
D. Hydroxyestrone

Answer 317

B. Estradiol (E2)

Question 318

319. The biologically most active, naturally occurring androgen is:

A. DHEA
B. Androstenedione
C. Epiandrosterone
D. Testosterone

Answer 318

D. Testosterone

Question 319

320. Zollinger–Ellison (Z–E) syndrome is characterized by great (e.g., 20-fold) elevation of:

A. Gastrin
B. Cholecystokinin
C. Pepsin
D. Glucagon

Answer 319

A. Gastrin

Question 320

321. Which of the following conditions can be quantified using a measurement technique known as the Ferriman-Gallwey Scale?

A. Acromegaly
B. Cushing’s syndrome
C. Hirsutism
D. PCOS

Answer 320

C. Hirsutism

Question 321

322. It is usually associated with a single, short-term exposure to a substance, the dose of which is sufficient to cause immediate toxic effects:

A. Acute toxicity
B. Chronic toxicity

Answer 321

A. Acute toxicity

Question 322

323. It is usually associated with repeated frequent exposure for extended periods for greater than 3 months and possibly years, at doses that are insufficient to cause an immediate acute response:

A. Acute toxicity
B. Chronic toxicity

Answer 322

B. Chronic toxicity

Question 323

324. Levels of 8-9% carboxyhemoglobin saturation of whole blood are commonly found in which of the following situations?

A. Fatal carbon monoxide poisoning
B. Acute carbon monoxide poisoning
C. Nonsmoking residents of rural areas
D. Cigarette smokers

Answer 323

D. Cigarette smokers

Rationale:

Heroin (diacetylmorphine), an abused drug, is a derivative of morphine. The morphine used in its synthesis is generally obtained from opium.

Question 324

325. Heroin is synthesized from what drug?

A. Diazepam
B. Morphine
C. Ecgonine
D. Chlorpromazine

Answer 324

B. Morphine

Rationale:

Heroin (diacetylmorphine), an abused drug, is a derivative of morphine. The morphine used in its synthesis is generally obtained from opium.

Question 325

326. THC (tetrahydrocannabinol) is the principal active component of what drug?

A. Benzodiazepine
B. Marijuana
C. Morphine
D. Codeine

Answer 325

B. Marijuana

Question 326

327. Which substance has the longest detection time?

A. Amphetamines
B. Cocaine
C. Benzodiazepines
D. Marijuana

Answer 326

D. Marijuana

Rationale:

Marijuana is stored in fatty tissue and is metabolized slowly.

In persons who use marijuana several times per week, cannabinoids can be detected several weeks after last use.

For chronic daily users, this extends to months after discontinuation.

Question 327

328. Methylenedioxymethylamphetamine (MDMA) is an illicit amphetamine derivative that is commonly referred to as:

A. Angel dust
B. Ecstacy
C. Marijuana
D. Shabu

Answer 327

B. Ecstacy

Question 328

329. The half-life of the circulating cocaine:

A. 0.5 to 1 hour
B. 1 to 2 hours
C. 2 to 3 hours
D. 3 to 4 hours

Answer 328

A. 0.5 to 1 hour

Question 329

330. Identification of the urinary metabolite benzoylecgonine would be useful in determining exposure to which of the following drugs?

A. Codeine
B. Cocaine
C. Amphetamine
D. Propoxyphene

Answer 329

B. Cocaine

Rationale:

Cocaine is an abused drug and not available for therapeutic use. After absorption, cocaine in the blood is rapidly converted into ecgonine and benzoylecgonine.

Question 330

331. All of the following are CNS depressant, EXCEPT:

A. Barbiturates
B. Benzodiazepines
C. Cocaine
D. Methaqualone

Answer 330

C. Cocaine

Rationale:

COCAINE IS A CNS STIMULANT.

CNS STIMULANTS
● Cocaine and its metabolite, benzoylecgonine, and amphetamines and methamphetamines

CNS DEPRESSANTS
● Barbiturates; methaqualone; benzodiazepines including Valium; and oxycodone and other opiates, including morphine, heroin (which metabolizes to morphine), codeine (methylmorphine), and methadone

HALLUCINOGENS OR PSYCHOACTIVES
● Cannabinoids and phencyclidine (PCP)

ANTIDEPRESSANTS
● Lithium, tricyclic antidepressants

Question 331

332. Of the following specimens, which would be appropriate for determining exposure to lead?

A. EDTA plasma
B. Serum
C. Whole blood
D. Cerebrospinal fluid

Answer 331

C. Whole blood

Rationale:

After absorption, lead is distributed into an active pool in the blood and soft tissue and a storage pool in bone, teeth, and hair. In blood, the majority is found in erythrocytes, with only minor quantities in plasma or serum. Lead is mainly excreted by the kidney; hence urine or whole blood would be appropriate specimens for determining lead exposure.

Question 332

333. This toxin has high affinity to keratin, can be identified from hair and nails:

A. Arsenic
B. Cyanide
C. Lead
D. Mercury

Answer 332

A. Arsenic

Rationale:

Toxins may BIND SULFHYDRYL GROUPS IN KERATIN FOUND IN HAIR AND FINGERNAILS

Question 333

334. Clues include the ODOR OF BITTER ALMONDS, the occurrence of an altered mental status and tachypnea in the absence of cyanosis, and an unexplained metabolic acidosis:

A. Arsenic toxicity
B. Carbon monoxide intoxication
C. Cyanide overdose
D. Iron poisoning

Answer 333

C. Cyanide overdose

Rationale:

The principal symptoms of cyanide overdose are tachypnea (initially), followed by respiratory depression and cyanosis, hypotension, convulsions, and coma. Death may occur in a matter of minutes because cyanide is a fast-acting toxin. Diagnosis may be difficult, and a high index of suspicion is needed to make the correct diagnosis.

Clues include the odor of bitter almonds, the occurrence of an altered mental status and tachypnea in the absence of cyanosis, and an unexplained metabolic acidosis (with an increased anion gap).

Question 334

335. The ODOR OF GARLIC may be on the breath, and a METALLIC TASTE in the patient’s mouth:

A. Arsenic toxicity
B. Carbon monoxide intoxication
C. Cyanide overdose
D. Iron poisoning

Answer 334

A. Arsenic toxicity

Question 335

336. Most common drug of abuse:

A. Cocaine
B. Ethanol
C. Methanol
D. Marijuana

Answer 335

B. Ethanol

Rationale:

Ethanol is probably the most common drug of abuse and is frequently responsible for the presentation of patients with altered mental status to hospitals and emergency rooms.

Question 336

337. Select the five pharmacological parameters that determine serum drug concentration.

A. Absorption, anabolism, perfusion, bioactivation, excretion
B. Liberation, equilibration, biotransformation, reabsorption, elimination
C. Liberation, absorption, distribution, metabolism, excretion
D. Ingestion, conjugation, integration, metabolism, elimination

Answer 336

C. Liberation, absorption, distribution, metabolism, excretion

Rationale:

LADME: Liberation, absorption, distribution, metabolism and excretion

1. Liberation is the release of the drug
2. Absorption is the transport of drug from the site of administration to the blood
3. Distribution refers to the delivery of the drug to the tissues
4. Metabolism is the process of chemical modification of the drug by cells
5. Excretion is the process by which the drug and its metabolites are removed from the body

Question 337

338. Blood sample collection time for peak drug levels:

A. Varies with the drug, depending on its rate of absorption
B. Is independent of drug formulation
C. Is independent of the route of administration
D. Is 30 minutes after a bolus intravenous injection is completed

Answer 337

A. Varies with the drug, depending on its rate of absorption

Rationale:

The peak concentration of a drug is the highest concentration obtained in the dosing interval.

For oral drugs, the time of peak concentration is dependent upon their rates of absorption and elimination and is determined by serial blood measurements. Peak levels for oral drugs are usually drawn 1–2 hours after administration of the dose. For drugs given intravenously, peak levels are measured immediately after the infusion is completed.

Question 338

339. When is a blood sample for determination of the trough level of a drug appropriately drawn?

A. During the absorption phase of the drug
B. During the distribution phase of the drug
C. Shortly before drug administration
D. Two hours after drug administration

Answer 338

C. Shortly before drug administration

Rationale:

When peak levels of the drug are required, the blood sample must be drawn at a specified time after drug administration.

Trough levels are most reliably determined by collecting the blood sample before the next drug administration.

Question 339

340. Which route of administration is associated with 100% bioavailability?

A. Sublingual
B. Intramuscular
C. Oral
D. Intravenous

Answer 339

D. Intravenous

Rationale:

When a drug is administered intravenously, all the drug enters the bloodstream.

Question 340

341. For what colorimetric determination is the Trinder reaction widely used?

A. Acetaminophen
B. Propoxyphene
C. Salicylate
D. Barbiturate

Answer 340

C. Salicylate

Question 341

342. Acetaminophen is particularly toxic to what organ?

A. Heart
B. Kidney
C. Spleen
D. Liver

Answer 341

D. Liver

Rationale:

Paracetamol, also known as acetaminophen.

Hepatotoxicity is common in acetaminophen overdose. It is particularly important to be able to determine the acetaminophen serum level rapidly so that the elimination half-life of the drug can be estimated. Hepatic necrosis is more common when the half-life exceeds 4 hours and is very likely when it exceeds 12 hours.

Question 342

343. Increased trough levels of aminoglycosides in the serum are often associated with toxic effects to which organ?

A. Heart
B. Kidney
C. Pancreas
D. Liver

Answer 342

B. Kidney

Question 343

344. Which of the following drugs is used as an immunosuppressant in organ transplantation, especially in liver transplants?

A. Methotrexate
B. Amiodarone
C. Tacrolimus
D. Paroxetine

Answer 343

C. Tacrolimus

Rationale:

Tacrolimus (Prograf) is an antibiotic that functions as an immunosuppressant in organ transplantation, especially in liver transplants.

Question 344

345. Which of the following drugs is used as a bronchodilator?

A. Theophylline
B. Phenytoin
C. Amikacin
D. Clozapine

Answer 344

A. Theophylline

Rationale:

Theophylline is a bronchodilator that is used to treat asthma. The therapeutic range is 10-20 ug/mL, and use must be monitored to avoid toxicity. Use of theophylline has been replaced where possible with beta-adrenergic agonists, which are available in the inhaled form.

Question 345

346. Bronchodilators:
347. 1.Digoxin
348. 2.Phencyclidine
349. 3.Theophylline
350. 4.Theobromine

A. 1 and 2
B. 1 and 3
C. 2 and 4
D. 3 and 4

Answer 345

D. 3 and 4

Question 346

347. Which of the following is a commonly encountered xanthine that could potentially interfere with the determination of theophylline?

A. Nicotine
B. Caffeine
C. Amphetamine
D. Procainamide

Answer 346

B. Caffeine

Rationale:

Theophylline, a xanthine with bronchodilator activity, is widely used in the treatment of asthma. Because of its availability and potential toxicity, it can also be subject to accidental overdose. Chromatographic methods are effective in separating theophylline from caffeine and theobromine, which are two commonly occurring and potentially interfering xanthines.

However, most clinical thin-layer chromatographic methods are relatively insensitive to the xanthines, and suspected theophylline overdose should be confirmed by HPLC or immunoassay methods.

Question 347

348. Which of the following is used in the treatment of manic depression?

A. Potassium
B. Lithium
C. Calcium
D. Chloride

Answer 347

B. Lithium

Rationale:

Lithium is used in the treatment of manic depression. Because of the small difference between therapeutic and toxic levels in the serum, accurate measurements of lithium concentrations are essential.

Question 348

349. The major toxicities of _______ are red man syndrome, nephrotoxicity, and ototoxicity.

A. Aminoglycosides
B. Cephalosporin
C. Penicillin
D. Vancomycin

Answer 348

D. Vancomycin

Rationale:

The major toxicities of vancomycin are red man syndrome, nephrotoxicity, and ototoxicity.

Red man syndrome is characterized by an erythemic flushing of the extremities.

The renal and hearing effects are similar to those of the aminoglycosides.

Question 349

350. The drug of choice for absence (petit mal) seizures unaccompanied by other types of seizures:

A. Carbamazepine (Tegretol)
B. Ethosuximide (Zarontin)
C. Primidone (Mysoline)
D. Valproic Acid (Depakene)

Answer 349

B. Ethosuximide (Zarontin)

Rationale:

Ethosuximide is the drug of choice for absence (petit mal) seizures unaccompanied by other types of seizures. It is preferred over valproic acid, at least initially, because hepatotoxicity is a rare but serious side effect of valproic acid.

Question 350

351. Which of the following do not require TDM?
352. Salicylates
353. Acetaminophen
354. Ibuprofen

A. 1 and 2
B. 1 and 3
C. 2 and 3
D. 1, 2 and 3

Answer 350

D. 1, 2 and 3

Rationale:

Most analgesics, such as salicylates, acetaminophen, and ibuprofen, do not require TDM because physicians and pharmacists are able to achieve and maintain therapeutic levels with standardized dosing intervals.

Because of the presumed safety of these medications, they are available without a prescription and sold as OVER-THE-COUNTER medications.

Question 351

89. LONG-TERM estimation of glucose concentration can be followed by measuring:

A. Glycosylated hemoglobin (HbA1c)
B. Fructosamine

Answer 351

A. Glycosylated hemoglobin (HbA1c)

Rationale:

Long-term estimation of glucose concentration can be followed by measuring glycosylated hemoglobin (Hb A1c). A level of 8% or less is considered “good” glycemic control.

Because the average red blood cell lives approximately 120 days, the glycosylated hemoglobin level at any one time reflects the average blood glucose level over the previous 2 to 3 months. Therefore, measuring the glycosylated hemoglobin provides the clinician with a time-averaged picture of the patient’s blood glucose concentration over the past 3 months.