CC

Question 1

Levels may become elevated as one changes position from supine to upright:

ACTH and cortisol
Aldosterone and insulin
Growth hormone and ACP
Albumin and calcium

Answer 1

Albumin and calcium

An upright position increases hydrostatic pressure, causing a reduction of plasma volume and increased concentration of proteins. Albumin and calcium levels may become elevated as one changes position from supine to upright.

Elements that are affected by postural changes are albumin, total protein, enzymes, calcium, bilirubin, cholesterol, triglycerides, and drugs bound to proteins.

Question 2

Peaks early to late morning; decreases up to 30% during the day:

Growth hormone
Acid phosphatase
Calcium
Iron

Answer 2

Iron

Cortisol: Peaks 4-6 AM; lowest 8 PM–12 AM; 50% lower at 8 PM than at 8 AM; increased with stress

Adrenocorticotropic hormone: Lower at night; increased with stress

Plasma renin activity: Lower at night; higher standing than supine

Aldosterone: Lower at night
Insulin: Lower at night

Growth hormone: Higher in afternoon and evening
Acid phosphatase: Higher in afternoon and evening

Thyroxine: Increases with exercise

Prolactin: Higher with stress; higher levels at 4 and 8 AM and at 8 and 10 PM

Iron: Peaks early to late morning; decreases up to 30% during the day

Calcium: 4% decrease supine

Question 3

Methods used to measure the concentrations of large particles such as antigen–antibody complexes, prealbumin, and other serum proteins:

Nephelometry
Turbidimetry
Nepholometry and turbidimetry
Nephelometry, turbidimetry and absorption spectroscopy

Answer 3

Nepholometry and turbidimetry

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 4

The measurement of voltage between two electrodes in a solution forms the basis for a variety of procedures for measuring analyte concentration:

Potentiometry
Coulometry
Amperometry
Voltammetry

Answer 4

Potentiometry

The measurement of potential (voltage) between two electrodes in a solution forms the basis for a variety of procedures for measuring analyte concentration.

Question 5

It is based on fragmentation and ionization of molecules using a suitable source of energy:

Conductance
Impedance
Chromatography
Mass spectrometry

Answer 5

Mass spectrometry

Question 6

Generally it is used to detect gamma radiation:

Crystal scintillation counter
Liquid scintillation counter
Crystal and liquid scintillation counter
None of these

Answer 6

Crystal scintillation counter

Crystal scintillation generally is used to detect gamma radiation. When a gamma ray penetrates the sodium iodide (NaI) crystal, which contains 1% thallium, it excites the electrons of iodide atoms and raises them to higher energy states.

Liquid scintillation is primarily used to count radionuclides that emit beta particles.

Question 7

A technique for determining the structure of organic compounds; it is nondestructive, although it does require a larger sample volume:

Mass spectroscopy
Nuclear magnetic resonanance
Capillary electrophoresis
Mass spectroscopy and nuclear magnetic resonance

Answer 7

Nuclear magnetic resonanance

Nuclear magnetic resonance spectroscopy (NMR) is a technique for determining the structure of organic compounds. Unlike mass spectroscopy (MS), NMR is nondestructive, although it does require a larger sample volume than MS. Although NMR is widely used as a diagnostic imaging technique, it has been adapted for only a limited number of clinical laboratory analyses, the most popular being lipoprotein particle measurements. It also has the unique capability of performing chemical analysis in vivo.

Question 8

Common causes of hypernatremia, EXCEPT:

Dehydration
Diabetes insipidus
Cushing’s disease or syndrome
Syndrome of inappropriate ADH (SIADH) secretion

Answer 8

Syndrome of inappropriate ADH (SIADH) secretion

HYPONATREMIA: Syndrome of Inappropriate ADH (SIADH) Secretion
In this condition, secondary to head trauma, seizures, other CNS diseases, and neoplastic conditions, especially lung, breast, and ovarian cancers that secrete ADH-like hormones, the serum sodium is depressed due to the excess retention of water in the collecting ducts.

Question 9

In all forms of hyponatremia, the chloride ion concentration is also generally ____ because chloride is the chief counterion for sodium.

High
Low
Variable
Cannot be determined

Answer 9

Low

In all forms of hyponatremia, the chloride ion concentration is also generally low because chloride is the chief counterion for sodium.

Question 10

Low anion gaps:

Uremia/renal failure
Uremia/renal failure, ketoacidosis and salicylate poisoning
Hypoalbuminemia and severe hypercalcemia
Hypoalbuminemia, hypercalcemia and multiple myeloma

Answer 10

Hypoalbuminemia, hypercalcemia and multiple myeloma

Low AG values are rare but may be seen with hypoalbuminemia (decrease in unmeasured anions) or severe hypercalcemia (increase
in unmeasured cations).

HENRY: Persistently low anion gaps are a serious sign of possible malignancy—for example, multiple myeloma.

Question 11

In panhepatic cirrhosis there is destruction of _____ of liver tissue.

Less than 50%
More than 50%
Less than 80%
More than 80%

Answer 11

More than 80%

Because in panhepatic cirrhosis there is destruction of more than 80% of liver tissue, with no regeneration of damaged liver tissue, the AST/ALT aminotransferases and LD levels (all from the regenerating nodules) tend to be normal or low, or occasionally mildly elevated. However, the total protein and albumin are both abnormally low.

In hepatitis, much less than 80% of the liver is destroyed, total regeneration will occur, and enough tissue is present to enable adequate levels of protein synthesis and ammonia fixation as urea. Therefore, the total protein and albumin and ammonia levels remain normal.

Question 12

A definitive test for congestive heart failure and appears to be an excellent marker for early heart failure:

CK and AST
CK, AST and LD
CK-MB and troponin
B-type natriuretic peptide

Answer 12

B-type natriuretic peptide

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 13

A definitive test for congestive heart failure and appears to be an excellent marker for early heart failure:

CK and AST
CK, AST and LD
CK-MB and troponin
B-type natriuretic peptide

Answer 13

B-type natriuretic peptide

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 14

The main waste product of nitrogen-containing chemicals in the body:

Ammonia
Creatinine
Urea
Uric acid

Answer 14

Urea

Urea is the main waste product of nitrogen-containing chemicals in the body.

Question 15

This protein appears in the urine when reabsorption is incomplete because of the proximal tubular damage as in acute kidney injury:

Urea
Creatinine
Alpha2-macroglobulin
Beta2-microglobulin

Answer 15

Beta2-microglobulin

Beta-2 microglobulin, a polypeptide with a molecular weight of 11.6 kDa with a length of 99 amino acids, is a component of the MHC (major histocompatibility complex) class I molecule.

The protein appears in the urine when reabsorption is incomplete because of the proximal tubular damage as in acute kidney injury.

Question 16

It is characterized by a sudden onset of hematuria and proteinuria and a decrease in glomerular filtration rate characterized by a rise in plasma creatinine and a fall in creatinine clearance compared with reference ranges:

Acute glomerular nephritis
Chronic glomerular nephritis
Diabetic nephropathy
Systemic lupus erythematosus

Answer 16

Acute glomerular nephritis

Question 17

Chronic glomerular nephritis

Slower developing disease and may be idiopathic
Characterized by gradual uremia
Loss of functioning nephrons
Slower developing disease and may be idiopathic, and is characterized by gradual uremia and loss of functioning nephrons

Answer 17

Slower developing disease and may be idiopathic, and is characterized by gradual uremia and loss of functioning nephrons

Chronic glomerular nephritis is a slower developing disease and may be idiopathic, and is characterized by gradual uremia and loss of functioning nephrons.

Question 18

A substance that increases the concentration of hydrogen ion (H+) when dissolved in water:

Acid
Base
Neutral
Buffer

Answer 18

Acid

Question 19

A substance that increases the concentration of hydroxyl ion (OH–) when dissolved in water:

Acid
Base
Neutral
Buffer

Answer 19

Base

Question 20

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

Acid
Base
Neutral
Buffer

Answer 20

Buffer

A buffer, the combination of a weak acid or weak base and its salt, is a system that resists changes in pH. The effectiveness of a buffer depends on the pKa of the buffering system and the pH of the environment in which it is placed. In plasma, the bicarbonate–carbonic acid system, having a pKa of 6.1, is one of the principal buffers.

Question 21

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

Kidney function
Lung function
Either kidney or lung function
None of these

Answer 21

Kidney function

The role of the lungs and kidneys in maintaining pH is depicted with the Henderson- Hasselbalch equation. The numerator (HCO3−) denotes kidney functions, and the denominator (Pco2) denotes lung function.

Question 22

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

Kidney function
Lung function
Either kidney or lung function
None of these

Answer 22

Lung function

The role of the lungs and kidneys in maintaining pH is depicted with the Henderson- Hasselbalch equation. The numerator (HCO3−) denotes kidney functions, and the denominator (Pco2) denotes lung function.

Question 23

Lung diseases such as chronic obstructive lung disease, advanced interstitial lung disease and acute asthma are causes of:

Respiratory acidosis
Respiratory alkalosis
Metabolic acidosis
Metabolic alkalosis

Answer 23

Respiratory acidosis

Question 24

The fifth most common element and is the most prevalent cation in the human body:

Calcium
Magnesium
Potassium
Sodium

Answer 24

Calcium

Calcium is the fifth most common element and is the most prevalent cation in the human body.

A healthy adult contains approximately 1 to 1.3 kg of calcium, and 99% of this is in the form of hydroxyapatite in the skeleton. The remaining 1% is contained in the extracellular fluid (ECF) and soft tissues. Additionally, less than 1% of the skeletal content of calcium is in bone fluid and exchanges freely with the ECF.

Question 25

The fourth most abundant cation in the body and the second most prevalent intracellular cation:

Calcium
Magnesium
Potassium
Sodium

Answer 25

Magnesium

Question 26

There usually is an autoimmune destruction of insulin-producing beta cells in the islets of the pancreas, causing an absolute deficiency in insulin production.

Type 1 diabetes mellitus
Type 2 diabetes mellitus
Type 1 and 2 diabetes
Gestational diabetes

Answer 26

Type 1 diabetes mellitus

Question 27

Most widely used to assess short-term(3- to 6-week) glycemic control:

Plasma glucose levels
Glycosylated hemoglobin
Fructosamine
Ketone testing

Answer 27

Fructosamine

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

Question 28

It plays a key role in role in reverse cholesterol transport, the process by which excess cholesterol is returned from tissues to the liver, where it is reused or excreted in bile:

Chylomicrons
VLDL
LDL
HDL

Answer 28

HDL

HDL plays a key role in reverse cholesterol transport, the process by which excess cholesterol is returned from tissues to the liver, where it is reused or excreted in bile.

Question 29

An abnormal lipoprotein found in patients with obstructive biliary disease and in patients with familial lecithin/cholesterol acyltransferase (LCAT) deficiency:

Intermediate-density lipoproteins
Lipoprotein (a)
LpX lipoprotein
LDL

Answer 29

LpX lipoprotein

LpX is an abnormal lipoprotein found in patients with obstructive biliary disease and in patients with familial lecithin/cholesterol acyltransferase (LCAT) deficiency.

Question 30

Lipoprotein(s) have a density of less than 1.006 kg/L (density measurement):

HDL
LDL
LDL and HDL
Chylomicrons and VLDL

Answer 30

Chylomicrons and VLDL

VLDL and chylomicrons are the most lipid-rich lipoprotein classes in human blood. This fact leaves them as the most buoyant in plasma. These lipoproteins have a density of less than 1.006 kg/L (density measurement).

LDL particles are smaller in size and in lipid content, causing their density to range from 1.006 to 1.063 kg/L.

HDL, the densest lipoprotein, ranges from 1.063 to 1.210 kg/L.

Question 31

A rare autosomal recessive disorder characterized by complete absence of HDL:

LCAT deficiency
Hepatic lipase deficiency
Familial hypoalphalipoproteinemia
Tangier disease

Answer 31

Tangier disease

Tangier disease is a rare autosomal recessive disorder characterized by
complete absence of HDL due to a mutation in the ABCA1 gene on chromosome 9.

In the homozygous state, patients present with low or undetectable HDL in plasma, hepatosplenomegaly, peripheral neuropathy, orange tonsils, and premature coronary disease.

Question 32

It plays a significant role in the metabolism of vitamin A by complexing with the retinol-binding protein (RBP), which, in turn, complexes with vitamin A to transport it through the body:

Albumin
Alpha1-antitrypsin
Prealbumin
Transferrin

Answer 32

Prealbumin

Prealbumin plays a significant role in the metabolism of vitamin A by complexing with the retinol-binding protein (RBP), which, in turn, complexes with vitamin A to transport it through the body.

Question 33

This protein, also known as orosomucoid, has a very high carbohydrate content, which minimizes its visualization by standard protein stains:

Gc-globulin
Hemopexin
C-reactive protein
Alpha1-acid glycoprotein

Answer 33

Alpha1-acid glycoprotein

Question 34

A striking elevation of transferrin in the β-region sometimes occurs in patients suffering from:

Acute inflammation
Chronic inflammation
Nephrotic syndrome
Iron deficiency anemia

Answer 34

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.

Question 35

Enzymes _____ the activation energies of the chemical reactions that they catalyze, so as to cause greatly enhanced rates of reaction.

Elevate
Lower
Affect variably
Produces no effect

Answer 35

Lower

Enzymes lower the activation energies of the chemical reactions that they catalyze, so as to cause greatly enhanced rates of reaction. They do not become modified in these reactions and do not affect the equilibrium between reactants and products in the reaction.

Question 36

Different forms of enzymes that catalyze the same reaction:

Activators
Coenzymes
Isoenzymes
Substrates

Answer 36

Isoenzymes

Many enzymes have isoenzymes, called isozymes, of different forms that catalyze the same reaction. These different forms occur because of differences in the amino acid sequences of enzymes.

Despite these differences in sequence, the enzymes fold to the same three-dimensional structures and frequently exhibit similar affinities for and catalytic rates with substrates.

Question 37

A nonprotein molecule necessary for enzyme activity:

Activators
Apoenzymes
Coenzymes
Cofactors

Answer 37

Cofactors

In addition to the basic enzyme structure, 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 NAD.

Question 38

Stated as E + S = ES = E + P

Catalytic mechanism
Henderson-Hasselbalch equation
Lineweaver-Burk plot
Michaelis-Menten

Answer 38

Catalytic mechanism

Question 39

In liver or skeletal muscle disease, which LD isozymes become elevated predominantly in serum?

LD1 and LD2
LD2 and LD3
LD3 and LD4
LD4 and LD5

Answer 39

LD4 and LD5

In myocardial damage, the predominant isozymes that become elevated in serum are LD1 and LD2; in liver or skeletal muscle disease, the LD4 and LD5 isozymes become elevated predominantly in serum.

Question 40

This probably represents alcohol dehydrogenase:

LD1
LD3
LD5
LD6

Answer 40

LD6

Another band detected in electrophoresis and termed LD6 can be seen; this probably represents alcohol dehydrogenase, which can also metabolize lactate.

Question 41

CHECK 3 BOXES: Causes of elevated serum levels of unconjugated bilirubin:

Dubin-Johnson syndrome
Biliary obstruction
Hemolysis
Gilbert’s syndrome
Crigler-Najjar syndrome

Answer 41

Hemolysis
Gilbert’s syndrome
Crigler-Najjar syndrome

Question 42

CHECK 2 BOXES: Causes of elevated serum levels of conjugated bilirubin:

Dubin-Johnson syndrome
Biliary obstruction
Hemolysis
Gilbert’s syndrome
Crigler-Najjar syndrome

Answer 42

Dubin-Johnson syndrome
Biliary obstruction

Question 43

Given the common practice of dismissing mother and newborn baby within 48 hours of the mother’s admission, it is likely that the neonate’s thyroxine levels may:

Increase above the normal reference ranges due to starvation
Increase above the normal reference ranges due to hyperthyroidism
Fall below normal references ranges due to congenital hypothyroidism
Fall below normal references ranges due to inadequate protein feeding

Answer 43

Fall below normal references ranges due to inadequate protein feeding

The common recommendation for neonatal testing is that specimens
are collected when the newborn is at least 3 days old and after 24 hours of protein feeding in order to adequately supply nutrients to produce thyroid hormones.

Given the common practice of dismissing mother and newborn baby
within 48 hours of the mother’s admission, it is likely that thyroxine levels may occasionally fall below normal reference ranges due to inadequate protein feeding rather than congenital hypothyroidism.

Question 44

It usually associated with a single, short-term exposure to a substance, the dose of which is sufficient to cause immediate toxic effects:

Acute toxicity
Chronic toxicity
Either acute or chronic toxicity
None of these

Answer 44

Acute toxicity

Acute toxicity is usually associated with a single, short-term exposure to a substance, the dose of which is sufficient to cause immediate toxic effects.

Question 45

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 response:

Acute toxicity
Chronic toxicity
Acute and chronic toxicity
None of these

Answer 45

Chronic toxicity

Chronic toxicity 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.

In many instances, chronic exposure is related to an accumulation of the toxicant or the toxic effects within the individual. Chronic toxicity may affect different systems than those associated with acute toxicity.

Question 46

This drug is traded on the streets under the name of angel dust or angel hair:

Cocaine
Amphetamine
Phencyclidine
Benzodiazepine

Answer 46

Phencyclidine

PHENCYCLIDINE
Used almost exclusively as a drug of abuse, this drug is traded on the streets under the name of angel dust or angel hair

Question 47

Panic reactions—a bad trip—are the most common adverse reactions.

Methaqualone
Marijuana
Phencyclidine
Lysergic acid diethylamide

Answer 47

Lysergic acid diethylamide

Lysergic acid diethylamide (LSD) is a semisynthetic indolalkylamine and a hallucinogen.

LSD toxicity levels are low, and deaths are generally due to trauma secondary to errors in the user’s judgment. Panic reactions—a bad trip—are the most common adverse reactions.

Question 48

The drug of choice for absence (petit mal) seizures unaccompanied by other types of seizures:

Ethosuximide (Zarontin)
Phenytoin (Dilantin)
Primidone (Mysoline)
Valproic Acid (Depakene)

Answer 48

Ethosuximide (Zarontin)

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 49

Anti-asthmatic drugs:

Digoxin
Digoxine and procainamide
Theophylline
Theophylline and theobromine

Answer 49

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.

Question 50

The most common drug of abuse and is frequently responsible for the presentation of patients with altered mental status to hospitals and emergency rooms:

Cocaine
Marijuana
Ethanol
Methanol

Answer 50

Ethanol

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.

Peak plasma concentrations are usually reached within 1 hour after ingestion.

Question 51

Lead is generally measured in:

CSF
Serum
Plasma
Whole blood

Answer 51

Whole blood

Unlike many other toxins, lead is generally measured in whole blood rather than in serum or plasma, because most of the circulating lead is bound within the blood cells.

Question 52

In an institution, a comprehensive program in which all areas of operation are monitored to ensure quality with the aim of providing the highest quality patient care:

Quality assessment
Quality assurance
Quality control
Quality systems

Answer 52

Quality systems

Quality assessment (QA) in the laboratory, a program that monitors the total testing process with the aim of providing the highest quality patient care; formerly called quality assurance.

Quality control (QC) a system that verifies the reliability of analytical test results through the use of standards, controls, and statistical analysis.

Quality systems (QS) in an institution, a comprehensive program in which all areas of operation are monitored to ensure quality with the aim of providing the highest quality patient care.

Question 53

An indication of error in the analysis, detected by a progressive drift of control values in one direction for at least 5 consecutive runs:

Dispesion
Shift
Trend
Random Error

Answer 53

Trend

TREND: an indication of error in the analysis, detected by a progressive drift of control values in one direction for at least 5 consecutive runs

Assaying control specimens and standards along with patient specimens serves several major functions:
1. Provides a guide to the functioning of equipment, reagents, and individual technique
2. Confirms the accuracy of testing when compared with reference values
3. Detects an increase in the frequency of both high and low minimally acceptable values (dispersion)
4. Detects any progressive drift of values to one side of the average value for at least 3 days (trends)
5. Demonstrates an abrupt shift or change from the established average value for 3 days in a row (shift)

Question 54

Centrifuge used when rapid centrifugation of solutions containing small particles is needed:

Horizontal-head centrifuge
Swinging-bucket centrifuge
Fixed-angle centrifuge
Cytocentrifuge

Answer 54

Fixed-angle centrifuge

Fixed angle–head centrifuges are used when rapid centrifugation of solutions containing small particles is needed; an example is the microhematocrit centrifuge.

Ultracentrifuges are high-speed centrifuges generally used for research projects, but for certain clinical uses, a small air-driven ultracentrifuge is available that operates at 90,000 to 100,000 rpm and generates a maximum RCF of 178,000 g. Ultracentrifuges are often refrigerated.

Question 55

Components of Quality Systems Program:

Personnel qualifications, training, and competency
Quality Assessment components including pre-analytical, analytical and post-analytical factors
Proficiency testing
All of these

Answer 55

All of these

COMPONENTS OF A QUALITY SYSTEMS PROGRAM
A comprehensive quality systems program is designed to follow a specimen all the way through the testing process, from the time a test is ordered, through specimen collection and testing to reporting, charting, and delivery and use of results. The scope of QS programs differs among laboratories, but in general QS programs are broad, ongoing, and encompass evaluation of:
1. Personnel qualifications, training, and competency
2. Quality Assessment components including preanalytical (before test) factors, analytical factors and QC methods and postanalytical (after test) factors
3. Proficiency testing

Question 56

An example of analytical factor affecting laboratory test result:

Patient identification procedure
Specimen labeling and transport
Reporting and charting of test results
Instrument maintenance and calibration

Answer 56

Instrument maintenance and calibration

Analytical Factors Affecting Laboratory Test Results
Quality assessment programs also evaluate analytical factors that can affect the actual test procedure. Many of these factors fall under the umbrella of QC. Analytical factors include:

1. Instrument maintenance and calibration
2. Use of standards and procedural controls
3. Techniques and test components associated with performing the test procedure (reagents, laboratory water, pipetting, timing, etc.)
4. Interfering substances or conditions
5. Statistical analysis of control results
   An example of an analytical error is inaccurate sampling caused by problems with an instrument’s automatic sampler, perhaps because of dirt or protein buildup in the sampling probe. The error might be detected when control values show an abrupt or steady change. Such an error can usually be prevented by performing recommended maintenance tasks.

Question 57

A method of monitoring accurate outcome; in which test samples from an external source are analyzed and results compared to those of reference laboratories and scored for accuracy:

Quality control
Quality assurance
Proficiency testing
Material safety data sheet

Answer 57

Proficiency testing

Proficiency testing (PT) is another component of laboratory quality programs. Laboratories that perform nonwaived procedures are required to subscribe to an external PT program. At regular intervals during the year, the PT agency sends blind samples to the laboratory. These are samples that have been assayed multiple times by the PT agency. The subscribing laboratory analyzes these blind samples and sends the results to the PT agency. The subscribing laboratory’s results are then compared to the PT agency’s assayed values and to the results of peer laboratories participating in the PT program. Participating laboratories receive a report evaluating their performance.

Question 58

Tests that are very simple or pose no reasonable risk of harm to the patient if the test is performed incorrectly:

Waived
Nonwaived

Answer 58

Waived

Question 59

Complex tests that require skill to perform and interpret and are therefore regulated:

Waived
Nonwaived

Answer 59

Nonwaived

Question 60

A procedure with minimal complexity, instrumentation, and personnel requirements so that the results can be quickly determined:

Definitive test
Presumptive test

Answer 60

Presumptive test
A procedure with minimal complexity, instrumentation, and personnel requirements so that the results can be quickly determined.

Question 60

A procedure with minimal complexity, instrumentation, and personnel requirements so that the results can be quickly determined:

Definitive test
Presumptive test

Answer 60

Presumptive test
A procedure with minimal complexity, instrumentation, and personnel requirements so that the results can be quickly determined.

Question 61

Highly sensitive and specific test in which results can be used as legal evidence:

Definitive test
Presumptive test

Answer 61

Definitive test
Highly sensitive and specific test in which results can be used as legal evidence

Question 62

It measures light blocked as a decrease in the light transmitted through the solution; dependent on particle size and concentration:

Nephelometry
Turbidimetry
Fluorometry
Chromatography

Answer 62

Turbidimetry

Turbidimetry measures light blocked as a decrease in the light transmitted through the solution; dependent on particle size and concentration.

Question 63

Ultraviolet (UV) light has _______ wavelengths.

Slightly short wavelengths
Very short wavelengths
Slightly long wavelengths
Very long wavelengths

Answer 63

Very short wavelengths

Ultraviolet (UV) light has very short wavelengths and infrared (IR) light has very long wavelengths. When all visible wavelengths of light (400-700 nm) are combined, white light results.

Question 64

Which of the following represents a primary advantage of performing fluorometric over absorption spectroscopic methods of analysis?

Increased specificity and increased sensitivity
Increased specificity and decreased sensitivity
Purity of reagents used not as critical
Ease of performing assays

Answer 64

Increased specificity and increased sensitivity

Fluorometric methods are extremely sensitive and highly specific. Because of this extreme sensitivity, reagents used must be of a higher degree of purity than is required for spectroscopy, because even slight traces of impurities may fluoresce.

Question 65

Large particles scattering light predominantly a in the forward direction:

Mie scatter
Raleigh scatter

Answer 65

Mie scatter

Mie scatter - large particles scattering light predominantly a in the forward direction

Raleigh scatter - small particles scattering light in all directions
with maximum scatter forward and backward

Question 66

Small particles scattering light in all directions with maximum scatter forward and backward:

Mie scatter
Raleigh scatter

Answer 66

Raleigh scatter

Mie scatter - large particles scattering light predominantly a in the forward direction

Raleigh scatter - small particles scattering light in all directions
with maximum scatter forward and backward

Question 67

Increasing temperature:

Fluorescence intensity increases
Fluorescence intensity decreases
Variable fluorescence
No relationship

Answer 67

Fluorescence intensity decreases

In general, fluorescence intensity decreases with increasing temperature by approximately 1 to 5% per degree Celsius.

Question 68

Pipettes have a cylindrical glass bulb near the center of the pipette that helps to distinguish them from other types of transfer pipettes:

Serological measuring pipettes
Mohr pipettes
Volumetric transfer pipettes
Ostwald-Folin transfer pipettes

Answer 68

Volumetric transfer pipettes

Question 69

Pipettes used for delivering small volumes of viscous solutions such as protein or whole blood standards:

Serological measuring pipettes
Mohr pipettes
Volumetric transfer pipettes
Ostwald-Folin transfer pipettes

Answer 69

Ostwald-Folin transfer pipettes

Question 70

High-speed centrifuges generally used for research projects, but for certain clinical uses, a small air-driven ultracentrifuge is available that operates at 90,000 to 100,000 rpm and generates a maximum RCF of 178,000 g; often refrigerated:

Horizontal-head centrifuge
Fixed angle-head centrifuge
Ultracentrifuge
Cytocentrifuge

Answer 70

Ultracentrifuge

Question 71

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

Horizontal-head centrifuge
Fixed angle-head centrifuge
Ultracentrifuge
Cytocentrifuge

Answer 71

Cytocentrifuge

This type of preparation can be used for blood, urine, body fluid, or any other liquid specimen that can be spread on a slide. An advantage of this technology is that only a small amount of sample is used, producing evenly distributed cells that can then be stained for microscopic study. The slide produced can be saved and examined at a later time, in contrast to “wet” preparations, which must be examined immediately.

Question 72

Fist pumping during venipuncture:

Decreased potassium and calcium
Decreased potassium, increased calcium
Increased potassium and calcium
Increased potassium, decreased calcium

Answer 72

Increased potassium and calcium

Fist pumping during venipuncture
↑ K+, lactic acid, Ca2+, phosphorus; ↓ pH

Pumping of the fist before venipuncture should be avoided because it causes an increase in plasma potassium, phosphate, and lactate concentrations. Lowering of blood pH by accumulation of lactate causes the plasma ionized calcium concentration to increase.

Question 73

Hemolysis is graded based on visible presence of hemoglobin, when greater than _____ mg/dL.

2 mg/dL
10 mg/dL
12 mg/dL
20 mg/dL

Answer 73

20 mg/dL

Hemolysis is generally a preanalytical problem that can be avoided. It is graded based on visible presence of hemoglobin, when greater than 20 mg/dL, and it is often graded as mild, moderate, or gross hemolysis.

Question 74

Glucose measurements can be _______by reducing methods than by more accurate enzymatic methods that are highly specific for glucose.

1 to 5 mg/dL erroneously higher
1 to 5 mg/dL erroneously lower
5 to 15 mg/dL erroneously higher
5 to 15 mg/dL erroneously lower

Answer 74

5 to 15 mg/dL erroneously higher

Glucose measurements can be 5 to 15 mg/dL erroneously higher by reducing methods than by more accurate enzymatic methods that are highly specific for glucose.

Question 75

Simple but nonspecific assay for creatinine:

Enzymatic
Colorimetric: endpoint
Colorimetric: kinetic
None of these

Answer 75

Colorimetric: endpoint

Question 76

Assay for uric acid that deals with turbidity problems and drug interferences:

Colorimetric
Enzymatic: UV
Enzymatic: H2O2
None of these

Answer 76

Colorimetric

Question 77

Using standard serum protein electrophoresis (SPE) methods, serum proteins appear in ____ bands.

Four bands
Five bands
Six bands
Twelve bands

Answer 77

Five bands

Standard SPE separates the protein into 5 distinct bands but, by modifying the electrophoretic parameters, proteins can be further separated into as many as 12 bands.

The modification, known as high-resolution protein electrophoresis (HRE), uses a higher voltage coupled with a cooling system in the electrophoretic apparatus and a more concentrated buffer.q

Question 78

What may be the cause of NEONATAL PHYSIOLOGICAL JAUNDICE of the hepatic type?

Hemolytic episode caused by an ABO incompatibility
Structure of the common bile duct
Hemolytic episode caused by an Rh incompatibility
Deficiency in the bilirubin conjugation enzyme system

Answer 78

Deficiency in the bilirubin conjugation enzyme system

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. Neonatal physiological jaundice resulting from an enzyme deficiency is hepatic in origin.

Question 79

Which of the following is not a type of support media used for serum protein electrophoresis?

Agarose gel
Cellulose acetate
Acrylamide
Celite

Answer 79

Celite

Support media that may be used for electrophoretic separations
include agarose gel, starch gel, cellulose acetate, and acrylamide.

Celite provides the inert supporting phase in gas-liquid chromatography.

Question 80

What dye may be used for staining protein bands following electrophoresis?

Fat red 7B
Sudan black B
Ponceau S
Oil red O

Answer 80

Ponceau S

Amido black 10B, Coomassie brilliant blue, and Ponceau S are dyes that are used to stain serum proteins after electrophoresis.

Oil red O and fat red 7B are dyes that are used to stain lipoproteins following electrophoresis.

Question 81

Using standard SPE, which protein travels farthest to the anode?

Alpha1-globulins
Alpha2-globulins
Beta-globulins
Gamma-globulins
Albumin

Answer 81

Albumin

Using standard SPE methods, serum proteins appear in five bands: albumin travels farthest to the anode, followed by α1-globulins, α2-globulins, β-globulins, and γ-globulins, in that order.

Question 82

Which term describes a congenital disorder that is characterized by a split in the albumin band when serum is subjected to electrophoresis?

Analbuminemia
Anodic albuminemia
Prealbuminemia
Bisalbuminemia

Answer 82

Bisalbuminemia

Bisalbuminemia is a congenital disorder that does not exhibit any clinical manifestations. The only sign of this disorder is the splitting of albumin into two distinct bands when serum is subjected to electrophoresis.

Question 83

All but one protein are components of the BETA-GLOBULINS:

Ceruloplasmin
Transferrin
Hemopexin
Complement components

Answer 83

Ceruloplasmin

CERULOPLASMIN - ALPHA2-GLOBULIN

Question 84

Which of the following dyes is the most specific for measurement of albumin?

Bromcresol green (BCG)
Bromcresol purple (BCP)
Tetrabromosulfonthalein
Tetrabromphenol blue

Answer 84

Bromcresol purple (BCP)

BCP is more specific for albumin than BCG.

However, BCG is the method used most often. One reason for this is that renal dialysis patients produce an organic acid that competes with BCP for the binding site on albumin, causing a falsely low result.

Question 85

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?

Inhibin A
Alpha-fetoprotein
Fetal fibronectin
Human chorionic gonadotropin

Answer 85

Fetal fibronectin

The level of fetal fibronectin increases in the secretions of the cervix and vagina. When this occurs prematurely, the increase in fetal fibronectin is used to predict risk of premature birth.

Inhibin A, alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol are used together in the quadruple test to assess risk for such disorders as Down syndrome.

Question 86

In which of the following disorders would the maternal serum level of alpha-fetoprotein not be elevated?

Neural tube defect
Spina bifida
Fetal distress
Down syndrome

Answer 86

Down syndrome

An increased AFP level in maternal serum is associated with such disorders as neural tube defects, spina bifida, and fetal distress.

A decreased AFP level in maternal serum is characteristic of Down syndrome.

Question 87

Which of the following is not quantified in the triple test for Down syndrome?

Alpha-fetoprotein
Unconjugated estriol
Progesterone
Human chorionic gonadotropin

Answer 87

Progesterone

SCREENING FOR BIRTH DEFECTS
1. Triple test: AFP, HCG and ESTRIOL
2. Quadruple (QUAD) screen: AFP, HCG, ESTRIOL and INHIBIN-A

Question 88

All antigen diffuse from the well and the concentration of the antigen is related to the square of the diameter of the precipitin ring:

Fahey-McKelvey or the kinetic RID
Mancini or the endpoint RID

Answer 88

Mancini or the endpoint RID

The endpoint method requires that all Ag diffuse from the well and the concentration of the Ag is related to the square of the diameter of the precipitin ring; the standard curve is plotted and a line of the best fit is computed.

To ensure that all of the Ag has diffused, the incubation time is 48 to 72 hours, depending on the molecular weight of the Ag; for example, IgG quantitation requires 48 hours, and IgM requires 72 hours.

For those performing RID, the endpoint method is favored because of its stability and indifference to temperature variations; however, turnaround time is longer compared with the kinetic method.

Question 89

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
Mancini or the endpoint RID

Answer 89

Fahey-McKelvey or the kinetic RID

The kinetic method requires that all rings be measured at a fixed time of 18 hours; a sample with a greater concentration will diffuse at a faster rate and will be larger at a fixed time.

The diameter of the precipitin ring is plotted against the Ag concentration on a logarithmic scale.

Question 90

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

Immediately after eating
Anytime during the day
In the fasting state, approximately 2 to 4 hours after eating
In the fasting state, approximately 12 hours after eating

Answer 90

In the fasting state, approximately 12 hours after eating

Question 91

Direct measurements of T4, except:

Dialysis
Immunoassay
Ultrafiltration
Uptake

Answer 91

Uptake

The FTI has been largely replaced by the direct measurement of free T4 by immunoassay, dialysis, or ultrafiltration.

Question 92

Errors in LDL-C become noticeable at triglycerides > _____ mg/dL and become unacceptably large at triglyceride levels > _____ mg/dL.

> 50 mg/dL, > 150 mg/dL
100 mg/dL, > 200 mg/dL
200 mg/dL, > 400 mg/dL
300 mg/dL, > 600 mg/dL

Answer 92

> 200 mg/dL, > 400 mg/dL

Errors in LDL-C become noticeable at triglyceride levels >2.26 mmol/L (200 mg/dL) and become unacceptably large at triglyceride levels >4.52 mmol/L (400 mg/dL).

Question 93

The Friedewald formula for computation of LDL-cholesterol is not valid for triglycerides over ___ mg/dL.

Over 100 mg/dL
Over 200 mg/dL
Over 300 mg/dL
Over 400 mg/dL

Answer 93

Over 400 mg/dL

The equation should not be used with triglyceride values exceeding 400 mg/dL because the VLDL composition is abnormal, making the [triglyceride/5] factor inapplicable.

Question 94

Compete with the substrate for the active site of the enzyme and prevent formation of product, but have a higher Km than the preferred substrate and can be overcome by addition of more substrate:

Competitive inhibitors
Noncompetitive inhibitors
Uncompetitive inhibitors

Answer 94

Competitive inhibitors

Competitive inhibitors: compete with the substrate for the active site of the enzyme and prevent formation of product, but have a higher Km than the preferred substrate and can be overcome by addition of more substrate.

Noncompetitive inhibitors: bind on a different active site of the enzyme than the substrate and so cannot be overcome by addition of more substrate, but prevent formation of product despite the enzyme-substrate complex.

Uncompetitive inhibitors: bind to the enzyme-substrate complex and prevent the formation of product. This type of inhibition is also reversible.

Question 95

Bind on a different active site of the enzyme than the substrate and so cannot be overcome by addition of more substrate, but prevent formation of product despite the enzyme-substrate complex:

Competitive inhibitors
Noncompetitive inhbitors
Uncompetitive inhibitors

Answer 95

Noncompetitive inhbitors

Competitive inhibitors: compete with the substrate for the active site of the enzyme and prevent formation of product, but have a higher Km than the preferred substrate and can be overcome by addition of more substrate.

Noncompetitive inhibitors: bind on a different active site of the enzyme than the substrate and so cannot be overcome by addition of more substrate, but prevent formation of product despite the enzyme-substrate complex.

Uncompetitive inhibitors: bind to the enzyme-substrate complex and prevent the formation of product. This type of inhibition is also reversible.

Question 96

Bind to the enzyme-substrate complex and prevent the formation of product:

Competitive inhibitors
Noncompetitive inhibitors
Uncompetitive inhibitors

Answer 96

Uncompetitive inhibitors

Question 97

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 of the amount of reaction that has occurred is made:

Kinetic method
Fixed-time method

Answer 97

Fixed-time method

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 of the amount of reaction that has occurred is made.

Question 98

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:

Kinetic method
Fixed-time method

Answer 98

Kinetic method

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 99

Most labile LD isoenzyme; loss of activity occurs more quicklyat 4°C than at 25°C.

LD-1
LD-2
LD-3
LD-4
LD-5

Answer 99

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 100

The International Federation for Clinical Chemistry (IFCC) recommends the use of methods such as the Bessey-Lowry-Brock method for determining alkaline phosphatase activity. The substrate used in this type of method is:

Monophosphate
Phenylphosphate
Disodium phenylphosphate
Para-nitrophenylphosphate

Answer 100

Para-nitrophenylphosphate

ALP catalyzes the hydrolysis of para-nitrophenyl phosphate forming phosphate and free 4-nitrophenyl (4-NPP) which, under alkaline conditions has very intense yellow color.

Question 101

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

8%
45%
92%
98%

Answer 101

92%

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 102

Hepatic cirrhosis:

Hypernateremia due to excess water loss
Hypernatremia due to decreased water intake
Hyponatremia due to increased sodium loss
Hyponatremia due to increased water retention

Answer 102

Hyponatremia due to increased water retention

Question 103

Diabetes insipidus:

Hypernatremia due to decreased water intake
Hypernatremia due to excess water loss
Hyponatremia due to increased sodium loss
Hyponatremia due to increased water retention

Answer 103

Hypernatremia due to excess water loss

Question 104

Artifactual hyperkalemia:

Sample hemolysis
Sample hemolysis, thrombocytosis
Sample hemolysis, excessive fist clenching
Sample hemolysis, thrombocytosis, prolonged tourniquet use or excessive fist clenching

Answer 104

Sample hemolysis, thrombocytosis, prolonged tourniquet use or excessive fist clenching

Question 105

Hormonal regulation of calcium:

Calcitonin, parathyroid hormone
Calcitonin, vitamin D
Parathyroid hormone, vitamin D
Parathyroid hormone, calcitonin and vitamin D

Answer 105

Parathyroid hormone, calcitonin and vitamin D

Question 106

It corrects renal blood flow in the following ways: causing vasodilation of the afferent arterioles and constriction of the efferent arterioles, stimulating reabsorption of sodium and water in the proximal convoluted tubules, and triggering the release of the sodium-retaining hormone aldosterone by the adrenal cortex and antidiuretic hormone by the hypothalamus:

Aldosterone
Angiotensin I
Angiotensin II
Renin

Answer 106

Angiotensin II

Question 107

Increased antidiuretic hormone:

Fluid loss, low serum sodium
Fluid loss, high serum sodium
Fluid retention, low serum sodium
Fluid retention, high serum sodium

Answer 107

Fluid retention, low serum sodium

Question 108

Decreased anion gaps of less than 10 mmol/L

Decreased measured cations or increased measured anions
Decreased unmeasured cations or decreased unmeasured anions
Increased measured cations or decreased measured anions
Increased unmeasured cations or decreased unmeasured anions
Increased unmeasured cations and anions
Decreased unmeasured cations and anions

Answer 108

Increased unmeasured cations or decreased unmeasured anions

Decreased anion gaps of less than 10 mmol/L: either an increase in unmeasured cations (Ca2+, Mg2+) or a decrease in the unmeasured anions

Anion gap exceeds 16 mmol/L Indication of increased concentrations of the unmeasured anions (PO4 3−, SO4 2−, protein ions)

Question 109

Serum osmolality increases by about ____ mOsm/kg for each 60 mg/dL increase in serum ethanol.

1 mOsm/kg
10 mOsm/kg
15 mOsm/kg
20 mOsm/kg

Answer 109

10 mOsm/kg

The degree of increase in osmolality due to ethanol is expressed as the difference between the measured and the calculated osmolality; the difference is called the osmolar gap.

Serum osmolality increases by about 10 mOsm/kg for each 60 mg/dL increase in serum ethanol.

Question 110

Blood received in the laboratory for blood gas analysis must meet which of the following requirements?

On ice, thin fibrin strands only, no air bubbles
On ice, no clots, fewer than 4 air bubbles
On ice, no clots, no air bubbles
Room temperature, no clots, no air bubbles

Answer 110

On ice, no clots, no air bubbles

Specimen requirements for blood gas analysis include the following.
1. Arterial blood is collected in a glass or plastic syringe. Capillary specimens can also be used (blood must be “arterialized”).
2. Lyophilized or liquid heparin is the preferred anticoagulant.
3. No air bubbles should exist in the sample because they lower the pCO2 value.
4. The specimen must be placed on ice and transported to the laboratory in 15 minutes at 4◦C and tested immediately. Otherwise, pH values decrease, and pCO2 values increase.
5. Blood clots are unacceptable.

Question 111

For each degree of fever in the patient, pO2 will ____ and pCO2 will ______.

pO2 an pCO2 will fall 7% and 3% respectively
pO2 and pCO2 will rise 3% and 7% respectively
pO2 will rise 7% and pCO2 will fall 3%
pO2 will fall 7% and pCO2 will rise 3%

Answer 111

pO2 will fall 7% and pCO2 will rise 3%

Question 112

What is the predominant form of thyroid hormone in the circulation?

Thyroxine
Triiodothyronine
Diiodotyrosine
Monoiodotyrosine

Answer 112

Thyroxine

T4 is the predominant form of the thyroid hormones secreted into the circulation, having a concentration in the plasma significantly greater than T3.

However, in terms of physiological activity, T3 must be considered because it is four to five times more potent than T4.

Question 113

The recommended initial thyroid function test for either a healthy, asymptomatic patient or a patient with symptoms which may be related to a thyroid disorder is:

Free thyroxine (free T4)
Thyroid-stimulating hormone (TSH)
Total thyroxine (T4)
Triiodothyronine (T3)

Answer 113

Thyroid-stimulating hormone (TSH)

TSH is the American Thyroid Association’s recommended screening test.

Question 114

Patient has signs and symptoms suggestive of acromegaly. The diagnosis would be confirmed if the patient had which of the following?

An elevated serum phosphate concentration
A decreased serum growth hormone releasing factor concentration
No decrease in serum growth hormone concentration 90 minutes after oral glucose administration
An increased serum somatostatin concentration

Answer 114

No decrease in serum growth hormone concentration 90 minutes after oral glucose administration

Following an overnight fast, a 100-gram oral glucose load will cause a large drop in serum growth hormone in a normal individual, but will not suppress in patients with acromegaly.

Question 115

The target DNA must be denatured to ____ before it can serve as a template for the PCR reaction.

Double-stranded DNA
Single-stranded DNA
Either dsDNA or ssDNA
None of these

Answer 115

Single-stranded DNA

The target DNA must be denatured to single-stranded DNA before it can serve as a template for the PCR reaction.

Question 116

An isotonic saline solution contains 0.85% NaCl. How many grams of NaCl are needed to prepare 5 L of this solution?

4.25 grams
8.5 grams
42.5 grams
425 gramss

Answer 116

42.5 grams