CC EXAMS Flashcards
The measurement of voltage between two electrodes in a solution forms the basis for a variety of procedures for measuring analyte concentration:
Potentiometry
It is based on fragmentation and ionization of molecules using a suitable source of energy:
Mass spectrometry
Generally it is used to detect gamma radiation:*
Crystal scintillation counter
A technique for determining the structure of organic compounds; it is nondestructive, although it does require a larger sample volume:
Nuclear magnetic resonanance
Low anion gaps:
Hypoalbuminemia, hypercalcemia and multiple myeloma
The main waste product of nitrogen-containing chemicals in the body:
Urea
The combination of a weak acid or weak base and its salt, is a system that resists changes in pH:
Buffer
The role of the lungs and kidneys in maintaining pH is depicted with the Henderson-Hasselbalch equation. The numerator denotes:
Kidney function
The role of the lungs and kidneys in maintaining pH is depicted with the Henderson-Hasselbalch equation. The denominator denotes:
Lung function
The fifth most common element and is the most prevalent cation in the human body:
Calcium
The fourth most abundant cation in the body and the second most prevalent intracellular cation:
Magnesium
An abnormal lipoprotein found in patients with obstructive biliary disease and in patients with familial lecithin/cholesterol acyltransferase (LCAT) deficiency:
LpX lipoprotein
Lipoprotein(s) have a density of less than 1.006 kg/L (density measurement):
Chylomicrons and VLDL
A striking elevation of transferrin in the β-region sometimes occurs in patients suffering from:
Iron deficiency anemia: A striking elevation of transferrin in the β-region sometimes occurs in patients suffering from iron deficiency anemia. The increase in transferrin corresponds to increased IBC, and the percent saturation is low.
Enzymes _____ the activation energies of the chemical reactions that they catalyze, so as to cause greatly enhanced rates of reaction.
Lower
Different forms of enzymes that catalyze the same reaction:
Isoenzymes
This probably represents alcohol dehydrogenase:
LD6
Stated as E + S = ES = E + P*
Catalytic mechanism
Panic reactions—a bad trip—are the most common adverse reactions.
Lysergic acid diethylamide
The drug of choice for absence (petit mal) seizures unaccompanied by other types of seizures:
Ethosuximide (Zarontin)
Anti-asthmatic drugs:
Theophylline and theobromine: Anti-asthmatic drugs, such as theophylline and theobromine, are used for treatment of neonatal breathing disorders or of respiratory conditions that affect adults or children, such as asthma.
An indication of error in the analysis, detected by a progressive drift of control values in one direction for at least 5 consecutive runs:
Trend
The most common drug of abuse and is frequently responsible for the presentation of patients with altered mental status to hospitals and emergency rooms:
Ethanol
Centrifuge used when rapid centrifugation of solutions containing small particles is needed:
Fixed-angle centrifuge
Tests that are very simple or pose no reasonable risk of harm to the patient if the test is performed incorrectly:
Waived
It measures light blocked as a decrease in the light transmitted through the solution; dependent on particle size and concentration:
Turbidimetry
Complex tests that require skill to perform and interpret and are therefore regulated:
Nonwaived
Small particles scattering light in all directions with maximum scatter forward and backward:
Raleigh scatter
Large particles scattering light predominantly a in the forward direction:*
Mie scatter
Hemolysis is graded based on visible presence of hemoglobin, when greater than _____ mg/dL.
20 mg/dL
Pipettes used for delivering small volumes of viscous solutions such as protein or whole blood standards:
Ostwald-Folin transfer pipettes
Pipettes have a cylindrical glass bulb near the center of the pipette that helps to distinguish them from other types of transfer pipettes:
Volumetric transfer pipettes
A very high-torque and low-inertia motor to spread monolayers of cells rapidly across a special slide for critical morphologic studies:
Cytocentrifuge
Using standard serum protein electrophoresis (SPE) methods, serum proteins appear in ____ bands.
Five bands
Which of the following is not quantified in the triple test for Down syndrome?
“Progesterone:SCREENING FOR BIRTH DEFECTS
1. Triple test: AFP, HCG and ESTRIOL
2. Quadruple (QUAD) screen: AFP, HCG, ESTRIOL and INHIBIN-A”
Which of the following is not a type of support media used for serum protein electrophoresis?
Celite
What dye may be used for staining protein bands following electrophoresis?
Ponceau S
All but one protein are components of the BETA-GLOBULINS
Ceruloplasmin
The physician is concerned that a pregnant patient may be at risk for delivering prematurely. What would be the best biochemical marker to measure to assess the situation?
Fetal fibronectin
All antigen diffuse from the well and the concentration of the antigen is related to the square of the diameter of the precipitin ring:
Mancini or the endpoint RID
It requires that all rings be measured at a fixed time of 18 hours; diameter of the precipitin ring is plotted against the antigen concentration on a logarithmic scale:
Fahey-McKelvey or the kinetic RID
Direct measurements of T4, except:
Uptake
Of the total serum osmolality, sodium, chloride, and bicarbonate ions normally contribute approximately what percent?
92%
Hepatic cirrhosis:
Hyponatremia due to increased water retention
Diabetes insipidus:
Hypernatremia due to excess water loss
Increased antidiuretic hormone:
Fluid retention, low serum sodium
Decreased anion gaps of less than 10 mmol/L
Increased unmeasured cations or decreased unmeasured anions
For each degree of fever in the patient, pO2 will ____ and pCO2 will ______.
pO2 will fall 7% and pCO2 will rise 3%
What is the predominant form of thyroid hormone in the circulation?
Thyroxine
Patient has signs and symptoms suggestive of acromegaly. The diagnosis would be confirmed if the patient had which of the following?
No decrease in serum growth hormone concentration 90 minutes after oral glucose administration
The target DNA must be denatured to ____ before it can serve as a template for the PCR reaction.
Single-stranded DNA
An isotonic saline solution contains 0.85% NaCl. How many grams of NaCl are needed to prepare 5 L of this solution?
42.5 grams
Excess CSF should be:
*
Frozen
Convert 50 mL to L
0.05
50 mL (milli = 10^-3 and is smaller) = ? L (larger by 10^3); move the decimal by three places to the left and it becomes 0.050 L.
Which of the following containers is calibrated to hold only one exact volume of liquid?
Volumetric flask
A Class A volumetric flask is calibrated to hold one exact volume of liquid (TC).
Which of the following standards requires that SDSs are accessible to all employees who come in contact with a hazardous compound?
Hazard Communication Standard
In the August 1987 issue of the Federal Register, OSHA published the new Hazard Communication Standard (Right to Know Law, 29 CFR 1910.1200).
Which of the following is the proper means of disposal for the type of waste?
Microbiologic waste by steam sterilization
Which of the following are examples of NONIONIZING RADIATION?
Ultraviolet light and microwaves
10 6th
Mega
Concentration expressed as the amount of solute per 100 parts of solution:
Percent solution
Indication of relative concentration:
Dilution
What is the molarity of a solution that contains 18.7 grams of KCl in 500 mL (MW 74.5)?
M = 18.7 g / (74.5)(0.5L) = 0.5 M
How much 95% v/v alcohol is required to prepare 5L of 70% v/v alcohol?
3.7 L
C1V1 = C2V2
V1 = (70)(5L) / 95 = 3.7 L
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?
1 to 100
Amount of serum: 0.1 mL
Total volume: 10 mL
Dilution: 0.1:10 or 1:100
Convert 72 Fahrenheit to its Celsius equivalent:
C = 5/9 (F - 32)
= 5/9 (72 - 32)
= 22.2C
Most basic pipette:
Glass pipette
ROUTINELY USED: automatic pipette
MOST BASIC: glass pipette
Does not have graduations to the tip:
Mohr pipet
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.
Pipets are used with biologic fluids having a viscosity greater than that of water:
Ostwald-Folin pipets
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.
Pipette with BULB CLOSER TO THE DELIVERY TIP and are used for accurate measurement of VISCOUS FLUIDS, such as blood or serum:
Ostwald-Folin pipette
Pipette with cylindrical glass bulb near the CENTER of the pipette that helps to distinguish them from other types of transfer pipettes.
Volumetric pipette
Extremely inert, excellent temperature tolerance and chemical resistance; used for stir bars, stopcocks and tubing:
Teflon
It is used when rapid centrifugation of solutions containing small particles is needed; an example is the microhematocrit centrifuge:
Fixed-angle head centrifuge
High-speed centrifuges used to separate layers of different specific gravities, commonly used to separate lipoproteins:
Ultracentrifuge
ULTRACENTRIFUGE
High-speed centrifuges used to separate layers of different specific gravities
Commonly used to separate lipoproteins
Usually refrigerated to counter heat produced through friction
Uses a very high-torque and low-inertia motor to spread MONOLAYER OF CELLS rapidly across a special slide for critical morphologic studies:
Cytocentrifuge
CYTOCENTRIFUGE
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
Calibration of centrifuges is customarily performed every ______.
*
Every 3 months (quarterly)
centrifuges are routinely disinfected on a ___ basis.
Weekly
Water produced using either an anion or a cation EXCHANGE RESIN, followed by replacement of the removed ions with hydroxyl or hydrogen ions.
Deionized water
The PUREST TYPE OF REAGENT WATER is:
Type I
Chemicals that are used to manufacture drugs:
USP and NF chemical grade
Which of the following is NOT A COLLIGATIVE PROPERTY of solutions?
pH
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
Degree of hazard #2:
Moderate
DEGREE OF HAZARD
0: NO OR MINIMAL
1: SLIGHT
2: MODERATE
3: SERIOUS
4: EXTREME
All of the following are CRYOGENIC MATERIALS HAZARDS, EXCEPT:
Shock
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.
When a person is receiving an electrical shock, all of the following should be done EXCEPT:
Pull the person away from the electrical source
When an accident involving electrical shock occurs:
The electrical source must be removed immediately. TURNING OFF THE CIRCUIT BREAKER, UNPLUGGING THE EQUIPMENT, or moving the equipment using a nonconductive glass or wood object are safe procedures to follow.
Most common source of light for work in the visible and near-infrared regions:
Incandescent tungsten or tungsten-iodide lamp
The most common source of light for work in the visible and near-infrared regions is the incandescent tungsten or tungsten-iodide lamp.
The lamps most commonly used for ultraviolet (UV) work are:
Deuterium discharge lamp and mercury arc lamp
Which is the most sensitive detector for spectrophotometry?
Photomultiplier
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.
Reflectance spectrometry uses which of the following?
Tungsten–halogen lamp
Slide technology depends on reflectance spectrophotometry.
For colorimetric determinations, the light source is a tungsten–halogen lamp.
Which of the following light sources is used in atomic absorption spectrophotometry?
Hollow-cathode lamp
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.
Used to measure concentration of LARGE PARTICLES: 1. Nephelometry 2. Turbidimetry 3. Absorption spectroscopy
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.
Which of the following techniques measures light scattered and has a light source placed at 90 degrees from the incident light?
Nephelometry
Which of the following instruments is used in the clinical laboratories to detect beta and gamma emissions?
Scintillation counter
Which of the following types of analyzers offers RANDOM-ACCESS CAPABILITIES?
Discrete analyzers
Checking instrument calibration, temperature accuracy, and electronic parameters are part of:
Function verification
Function verification includes monitoring temperature, setting electronic parameters, calibrating instruments and analyzing control data.
A pre-analytical error can be introduced by:
Vigorously shaking the blood tube to prevent clotting
Vigorously mixing can cause hemolysis.
The following data were calculated on a series of 30 determinations of serum uric acid control: mean = 5.8 mg/dL, 1 standard deviation = 0.15 mg/dL. If confidence limits are set at ± 2 SD, which o f the following represents allowable limits for the control?
5.50 to 6.10 mg/dL
Standard deviation is a measure of the dispersion of data around the mean.
Systematic errors include: PLEASE CHECK 3 BOXES.
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
Random errors include: PLEASE CHECK 3 BOXES.
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
Most frequently occurring value in a dataset:
MODE
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.
Type of systemic error in the sample direction and magnitude; the magnitude of change is constant and not dependent on the amount of analyte.
Constant error: Type of systemic error in the sample direction and magnitude; the magnitude of change is constant and not dependent on the amount of analyte.
Type of systemic error where the magnitude changes as a percent of the analyte present; error dependent on analyte concentration.
Proportional error:
Type of systemic error where the magnitude changes as a percent of the analyte present; error dependent on analyte concentration.
Difference between the observed mean and the reference mean:
Bias:
Difference between the observed mean and the reference mean.
The term R:4S means that:
Two controls in the same run are greater than 4s units apart
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).
Which of the following terms refers to deviation from the true value caused by indeterminate errors inherent in every laboratory measurement?
Random error
Random errors are deviations from the true value caused by unavoidable errors inherent in laboratory measurements.
A trend in QC results is most likely caused by:
Deterioration of the reagent
MAIN CAUSE OF TREND: DETERIORATION OF REAGENTS
A trend occurs when six or more consecutive quality control results either increase or decrease in the same direction; however, this is not cause for rejection until a multirule is broken. Trends are systematic errors (affecting accuracy) linked to an unstable reagent, calibrator, or instrument condition.
Which of the following plots is best for detecting all types of QC errors?
Levy–Jennings
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.
Which of the following plots is best for comparison of precision and accuracy among laboratories?
Tonks–Youden
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.
Which plot will give the earliest indication of a shift or trend?
Cusum
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.
Which of the following terms refers to the closeness with which the measured value agrees with the true value?
Accuracy
Which of the following describes the ability of an analytical method to maintain both accuracy and precision over an extended period of time?
Reliability
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:
120 minutes (2 hours)
Glucose measurements can be ____ mg/dL erroneously higher by reducing methods than by more accurate enzymatic methods.
5 to 15 mg/dL
Select the enzyme that is most specific for beta D-glucose:
Glucose oxidase
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.
Select the coupling enzyme used in the hexokinase method for glucose:
Glucose-6-phosphate dehydrogenase
Gross hemolysis and extremely elevated bilirubin may cause ______ in HEXOKINASE RESULTS.
False decrease
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.
Resting plasma glucose
NORMAL <140
IMPAIRED 140 – 199
DIAGNOSTIC ≥ 200 mg/dL
Fasting plasma glucose
NORMAL <100
IMPAIRED 100 – 125
DIAGNOSTIC ≥ 126 mg/dL
What is the recommended cutoff value for adequate control of blood glucose in diabetics as measured by glycated hemoglobin?
6.5%
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.
2-hour OGTT
NORMAL <140
IMPAIRED 140 – 199
DIAGNOSTIC ≥ 200 mg/dL
HbA1c
NORMAL <5.7 %
IMPAIRED 5.7 – 6.4%
DIAGNOSTIC ≥ 6.5%
Which test is the most sensitive in detecting early monoclonal gammopathies?
Serum-free light chain immunoassay
Measurement of free light chains is recommended along with protein electrophoresis when testing for myeloma.
Free light chains are normally present in serum because L chains are made at a faster rate than H chains.
Patients with Waldenström’s macroglobulinemia exhibit abnormally large amounts of:
IgM
Waldenström’s primary macroglobulinemia (WM), or simply macroglobulinemia, is a B cell disorder characterized by the infiltration of lymphoplasmacytic cells into bone marrow and the presence of an IgM monoclonal gammopathy.
Which test is the most useful way to evaluate the response to treatment for multiple myeloma?
Measurement of serum-free light chains
Unlike electrophoresis methods, serum free light chain assays are quantitative and an increase in free light chain production with an abnormal kappa:lambda ratio occurs earliest in recurrence of myeloma.
A sensitive, although not specific indicator of damage to the kidneys:
Proteinuria
At pH 8.6, proteins are _________ charged and migrate toward the _________.
Negatively, anode
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?
BCG (Bromcresol green)