All Questions Pt.2 Flashcards by Rhoan Jane Altura Calunsag

SITUATION: A blood sample in a red-stoppered tube is delivered to the laboratory for electrolytes, calcium, and phosphorus. The tube is approximately half full and is accompanied by a purple stoppered tube for a complete blood count that is approximately three-quarters full. The chemistry results are as follows:
Na K Cl HCO3 Ca InP
135 mmol/L 11.2 mmol/L 103 mmol/L 14 mmol/L 2.6 mg/dL 3.8 mg/dL
What is the most likely explanation of these serum calcium results?

A. Severe hemolysis during sample collection
B. Laboratory error in the calcium measurement
C. The wrong order of draw was used for vacuum tube collection
D. Some anticoagulated blood was added to the red-stoppered tube

D. Some anticoagulated blood was added to the red-stoppered tube

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SITUATION: A patient previously diagnosed with primary hypothyroidism and started on thyroxine replacement therapy is seen for follow-up testing after 2 weeks. Te serum-free T4 is normal but the TSH is still elevated. What is the most likely explanation for these results?

A. Laboratory error in measurement of free T4
B. Laboratory error in measurement of TSH
C. In vitro drug interference with the free T4 assay
D. Results are consistent with a euthyroid patient in the early phase of therapy

D. Results are consistent with a euthyroid patient in the early phase of therapy

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SITUATION: A 6-year-old child being treated with phenytoin was recently placed on valproic acid for better control of seizures. After displaying signs of phenytoin toxicity including ataxia, a stat phenytoin is determined to be 15.0 mg/L (reference range 10 20 mg/L). A peak blood level drawn 5 hours after the last dose is 18.0 mg/L. The valproic acid measured at the same time is within therapeutic limits. Quality control is within acceptable limits for all tests, but the physician questions the accuracy of the results. What is the most appropriate next course of action?

A. Repeat the valproic acid level using the last specimen
B. Repeat the phenytoin on both trough and peak samples using a different method
C. Recommend measurement of free phenytoin using the last specimen
D. Recommend a second trough level be measured

C. Recommend measurement of free phenytoin using the last specimen

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Na K Cl HCO3 BUN Glucose Creatinine Uric Acid
140 mmol/L 3.6 mmol/L 100 mmol/L 28 mmol/L 130 mg/dL 110 mg/dL 1.2 mg/dL 4.8 mg/dL

148 mmol/L 4.2 mmol/L 110 mmol/L 24 mmol/L 135 mg/dL 86 mg/dL 0.8 mg/dL 3.9 mg/dL

138 mmol/L 4.0 mmol/L 105 mmol/L 22 mmol/L 142 mg/dL 190 mg/dL 1.0 mg/dL 4.6 mg/dL

The results shown in the table above are obtained from three consecutive serum samples using an automated random access analyzer that samples directly from a bar-coded tube. Calibration and QC performed at the start of the shift are within the acceptable range, and no error codes are reported by the analyzer for any tests on the three samples. Upon results verification, what is the most appropriate course of action?

A. Report the results and proceed with other tests since no analytical problems are noted
B. Repeat the controls before continuing with further testing, but report the results
C. Check sample identification prio
D. Do not report BUN results for these patients or continue BUN testing

D. Do not report BUN results for these patients or continue BUN testing

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An AFP measured on a 30-year-old pregnant woman at approximately 12 weeks gestation is 2.5 multiples of the median (MOM). What course of action is most appropriate?

A. Repeat the serum AFP in 2 weeks
B. Recommend AFP assay on amniotic fluid
C. Repeat the AFP using the same sample by another method
D. Repeat the AFP using the sample by the same method

A. Repeat the serum AFP in 2 weeks

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AST ALT ALP LD CK GGT TP ALB TBIL GLU TG CA InP BUN
U/L U/L U/L U/L U/L U/L g/dL g/dL mg/dL mg/dL mg/dL mg/dL mg/dL mg/dL
Day 1 20 15 40 100 15 40 8.2 3.6 0.8 84 140 8.7 4.2 16

Day 2 22 14 65 90 20 36 8.3 3.8 1.0 128 190 8.8 5.2 26

SITUATION: Biochemistry tests are performed 24 hours apart on a patient and delta-check flag is reported for inorganic phosphorus by the laboratory information system. Given the results shown in the table above, identify the most likely cause.

A. Results suggest altered metabolic status caused by poor insulin control
B. The patient was not fasting when the sample was collected on day 2
C. The samples were drawn from two different patients
D. The delta-check limit is invalid when samples are collected 24 or more hours apart

B. The patient was not fasting when the sample was collected on day 2

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A quantitative sandwich enzyme immunoassay for intact serum hCG was performed on week 4 and the result was 40,000 mIU/mL (reference range 10,000-80,000 mIU/mL). The physician suspected a molar pregnancy and requested that the laboratory repeat the test checking for the hook effect. Which process would identify this problem?

A. Obtain a new plasma specimen and heat inactivate before testing
B. Obtain a urine specimen and perform the assay
C. Perform a qualitative pregnancy test
D. Perform a serial dilution of the sample and repeat the test

D. Perform a serial dilution of the sample and repeat the test

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A patient presents to the emergency department with symptoms of intoxication including impaired speech and movement. Te plasma osmolality was measured and found to be 330 mOs/kg. Te osmolal gap was 40 mOsm/Kg. A blood alcohol was measured by the alcohol dehydrogenase method and found to be 0.15% w/v (150 mg/dL). Electrolyte results showed an increased anion gap. Ethylene glycol intoxication was suspected because the osmolal gap was greater than could be explained by ethanol alone, but gas chromatography was not available. Which of the following would be abnormal if this suspicion proved correct?

A. Arterial blood gases
B. Lactic acid
C. Urinary ketones
D. Glucose

A. Arterial blood gases

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Given the serum protein electrophoresis pattern shown, which transaminase results would you expect?

A. Within normal limits for both
B. Marked elevation of both (20-50-fold normal)
C. Mild elevations of both (2-5-fold normal)
D. Marked elevation of AST but normal AL

C. Mild elevations of both (2-5-fold normal)

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Serial TnI assays are ordered on a patient at admission, 3 hours, and 6 hours afterwards. The samples were collected in heparinized plasma separator tubes. Following are the results (reference range 0 0.03 µg/L

Admission = 3 hours = 6 hours =
0.03 µg/L 0.07 µg/L 0.02 µg/

These results indicate:
A. A positive test for acute myocardial infarction
B. Unstable angina
C. Cardiac injury of severity less than myocardial infarction
D. Random error with the 3-hour sample

D. Random error with the 3-hour sample

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In which of the following cases is qualitative analysis of the drug usually adequate?

A. To determine whether the dose of a drug with a low therapeutic index is likely to be toxic
B. To determine whether a patient is complying with the physician’s instructions
C. To adjust dose if individual differences or disease alter expected response
D. To determine whether the patient has been taking amphetamines

D. To determine whether the patient has been taking amphetamines

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The term pharmacokinetics refers to the:

A. Relationship between drug dose and the drug blood level
B. Concentration of drug at its sites of action
C. Relationship between blood concentration and therapeutic response
D. The relationship between blood and tissue drug levels

A. Relationship between drug dose and the drug blood level

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The term pharmacodynamics is an expression of the relationship between:

A. Dose and physiological effect
B. Drug concentration at target sites and physiological effect
C. Time and serum drug concentration
D. Blood and tissue drug levels

B. Drug concentration at target sites and physiological effect

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The study of pharmacogenomics involves which type of testing?

A. Family studies to determine the inheritance of drug resistance
B. Testing drugs with cell cultures to determine the minimum toxic dosage
C. Testing for single nucleotide polymorphisms known to affect drug metabolism
D. Comparison of dose-response curves between family members

C. Testing for single nucleotide polymorphisms known to affect drug metabolism

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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

C. Liberation, absorption, distribution, metabolism, excretion

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Which route of administration is associated with 100% bioavailability?

A. Sublingual
B. Intramuscular
C. Oral
D. Intravenous

D. Intravenous

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The phrase “first-pass hepatic metabolism” means that:

A. One hundred percent of a drug is excreted by the liver
B. All drug is inactivated by hepatic enzymes after one pass through the liver
C. Some drug is metabolized from the portal circulation, reducing bioavailability
D. The drug must be metabolized in the liver to an active form

C. Some drug is metabolized from the portal circulation, reducing bioavailability

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Which formula can be used to estimate dosage needed to give a desired steady-state blood level?

A. Dose per hour = clearance (milligrams per hour) × average concentration at steady state ÷ f
B. Dose per day = fraction absorbed - fraction excreted
C. Dose = fraction absorbed × (1/protein-bound fraction)
D. Dose per day = half-life × log Vd (volume distribution)

A. Dose per hour = clearance (milligrams per hour) × average concentration at steady state ÷ f

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Which statement is true regarding the volume distribution (Vd) of a drug?

A. Vd is equal to the peak blood concentration divided by the dose given
B. Vd is the theoretical volume in liters into which the drug distributes
C. The higher the Vd, the lower the dose needed to reach the desired blood level of drug
D. The Vd is the principal determinant of the dosing interval

B. Vd is the theoretical volume in liters into which the drug distributes

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For drugs with first-order elimination, which statement about drug clearance is true?

A. Clearance = elimination rate ÷ serum level
B. It is most often performed by the liver
C. It is directly related to half-life
D. Clearance rate is independent of dose

A. Clearance = elimination rate ÷ serum level

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Which statement about steady-state drug levels is true?

A. The absorbed drug must be greater than the amount excreted
B. Steady state can be measured after two elimination half-lives
C. Constant intravenous infusion will give the same minima and maxima as an oral dose
D. Oral dosing intervals give peaks and troughs in the dose-response curve

D. Oral dosing intervals give peaks and troughs in the dose-response curve

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If too small a peak-trough difference is seen for a drug given orally, then:

A. The dose should be decreased
B. Time between doses should be decreased
C. Dose interval should be increased
D. Dose per day and time between doses should be decreased

C. Dose interval should be increased

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If the peak level is appropriate but the trough level too low at steady state, then the dose interval should:

A. Be lengthened without changing the dose per day
B. Be lengthened and dose rate decreased
C. Not be changed, but dose per day increased
D. Be shortened, but dose per day not changed

D. Be shortened, but dose per day not changed

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When should blood samples for trough drug levels be collected?

A. 30 minutes after peak levels
B. 45 minutes before the next dose
C. 1-2 hours after the last dose
D. Immediately before the next dose is given

D. Immediately before the next dose is given

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If the steady-state drug level is too high, the best course of action is to: A. Decrease the dose B. Decrease the dose interval C. Decrease the dose and decrease the dose interval D. Change the route of administration

A. Decrease the dose

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

A. Varies with the drug, depending on its rate of absorption

Which could account for drug toxicity following a normally prescribed dose? A. Decreased renal clearance caused by kidney disease B. Discontinuance or administration of another drug C. Altered serum protein binding caused by disease D. All of these options

D. All of these options

Select the elimination model that best describes most oral drugs. A. One compartment, linear first-order elimination B. Michaelis-Menton or concentration-dependent elimination C. Two compartment with a biphasic elimination curve D. Logarithmic elimination

A. One compartment, linear first-order elimination

Drugs rapidly infused intravenously usually follow which elimination model? A. One compartment, first order B. One compartment, logarithmic C. Biphasic or two compartment with serum level rapidly falling in the first phase D. Michaelis-Menton or concentration-dependent elimination

C. Biphasic or two compartment with serum level rapidly falling in the first phase

Which fact must be considered when evaluating a patient who displays signs of drug toxicity? A. Drug metabolites (e.g., N-acetylprocainamide) may need to be measured as well as parent drug B. If the concentration of total drug is within therapeutic limits, the concentration of free drug cannot be toxic C. If the drug has a wide therapeutic index, then it will not be toxic D. A drug level cannot be toxic if the trough is within the published therapeutic range

A. Drug metabolites (e.g., N-acetylprocainamide) may need to be measured as well as parent drug

When a therapeutic drug is suspected of causing toxicity, which specimen is the most appropriate for an initial investigation? A. Trough blood sample B. Peak blood sample C. Urine at the time of symptoms D. Gastric fluid at the time of symptoms

B. Peak blood sample

For which drug group are both peak and trough measurements usually required? A. Antiarrhythmics B. Analgesics C. Tricyclic antidepressants D. Aminoglycoside antibiotics

D. Aminoglycoside antibiotics

For a drug that follows first-order pharmacokinetics, adjustment of dosage to achieve the desired blood level can be made using which formula? A. New dose = current dose /concentration at steady state × (desired concentration) B. New dose = current dose/desired concentration × (concentration at steady state) C. New dose = concentration at steady state/ desired concentration × (half-life) D. New dose = concentration at steady state/ current dose × (desired concentration)

A. New dose = current dose /concentration at steady state × (desired concentration)

Which of the following statements about TLC for drug screening is true? A. Acidic drugs are extracted in an alkaline nonpolar solvent B. A drug is identified by comparing its Rf value and staining to standards C. Testing must be performed using a urine sample D. Opiates and other alkaloids are extracted at an acid pH

B. A drug is identified by comparing its Rf value and staining to standards

The EMIT for drugs of abuse uses an: A. Antibody conjugated to a drug B. Enzyme conjugated to an antibody C. Enzyme conjugated to a drug D. Antibody bound to a solid phase

C. Enzyme conjugated to a drug

Which statement about EMIT is true? A. Enzyme activity is inversely proportional to drug level B. Formation of NADH is monitored at 340 nm C. ALP is the commonly used conjugate D. Assay use is restricted to serum

B. Formation of NADH is monitored at 340 nm

Which statement regarding cloned enzyme donor immunoassay (CEDIA) is true? A. The enzyme used is glucose-6-phosphate dehydrogenase B. The enzyme donor and acceptor molecules are fragments of β-galactosidase C. Drug concentration is inversely related to fluorescence D. The antibody is covalently linked to the enzyme donor

B. The enzyme donor and acceptor molecules are fragments of β-galactosidase

Which statement is true regarding particle-enhanced turbidimetric inhibition immunoassay methods for therapeutic drugs? A. Drug concentration is proportional to light scatter B. Magnetic separation is needed to remove unbound conjugate C. When particle-bound drug binds to antibody, light scattering is increased D. Two antibodies to the drug are needed

C. When particle-bound drug binds to antibody, light scattering is increased

Quantitation of a drug by gas chromatography-mass spectroscopy (GC-MS) is usually performed in which mode? A. Total ion chromatography B. Selective ion monitoring C. Ion subtraction D. Selective reaction monitoring

B. Selective ion monitoring

Which substance has the longest detection time? A. Amphetamines B. Cocaine C. Benzodiazepines D. Marijuana

D. Marijuana

SITUATION: A urine sample is received in the laboratory with the appropriate custody control form, and a request for drug of abuse screening. Which test result would be cause for rejecting the sample? A. Temperature after collection 95°F B. pH 5.0 C. Specific gravity 1.005 D. Creatinine 5 mg/dL

D. Creatinine 5 mg/dL

Which statement about the measurement of carboxyhemoglobin is true? A. Treatment with alkaline dithionite is used to convert carboxyhemoglobin to oxyhemoglobin B. Oxyhemoglobin has no absorbance at 540 nm, but carboxyhemoglobin does C. Bichromatic analysis is required in order to eliminate interference by oxyhemoglobin D. Carboxyhemoglobin can be measured by potentiometry

C. Bichromatic analysis is required in order to eliminate interference by oxyhemoglobin

Which of the following statements about blood alcohol measurement is correct? A. Symptoms of intoxication usually begin when the level exceeds 0.05% w/v B. The skin puncture site should be disinfected with isopropanol C. The reference method is based upon enzymatic oxidation of ethanol by alcohol dehydrogenase D. Gas chromatography methods require extraction of ethanol from serum

A. Symptoms of intoxication usually begin when the level exceeds 0.05% w/v

Which specimen is the sample of choice for lead screening? A. Whole blood B. Hair C. Serum D. Urine

A. Whole blood

Which of the following enzymes can be used to measure plasma or serum salicylate? A. Peroxidase B. Salicylate esterase C. Salicylate hydroxylase D. p-Aminosalicylate oxidase

C. Salicylate hydroxylase

Which of the following tests is least essential to the operation of an emergency department at a general hospital? A. Carboxyhemoglobin B. Osmolality C. Salicylate D. Lead

D. Lead

Which of the following trace elements is considered an essential micronutrient? A. Thallium B. Aluminum C. Mercury D. Selenium

D. Selenium

When measuring trace metals in blood other than lead, what type of tube should be used? A. Navy blue top B. Green top C. Purple top D. Red top

A. Navy blue top

Which whole-blood level is suggestive of excessive exposure to lead in children but not adults? A. 4 µg/dL B. 14 µg/dL C. 28 µg/dL D. 32 µg/dL

B. 14 µg/dL

What are the likely laboratory findings in a person suspected of having Wilson's disease? A. Blood copper and ceruloplasmin low, urinary copper excretion high B. Blood and urine copper concentration high, ceruloplasmin low C. Blood and urine copper concentration high, ceruloplasmin high D. Blood and urine copper concentration low, ceruloplasmin low

A. Blood copper and ceruloplasmin low, urinary copper excretion high

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

C. Serum ACTH

In which situation is the plasma or 24-hour urinary cortisol not consistent with the clinical picture? A. In pregnant patients B. In patients with a positive overnight dexamethasone suppression test C. In congenital adrenal hyperplasia D. In Cushing's syndrome caused by ectopic ACTH producing tumors

C. In congenital adrenal hyperplasia

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

A. Overnight low-dose dexamethasone suppression test

Which of the following statements about the diagnosis of Addison's disease is true? A. Patients with primary Addison's disease show a normal response to ACTH stimulation B. Primary and secondary Addison's disease can often be differentiated by plasma ACTH C. Twenty-four-hour urinary free cortisol is normal in Addison's disease D. Pituitary ACTH reserves are normal in secondary Addison's disease

B. Primary and secondary Addison's disease can often be differentiated by plasma ACTH

Which test is the most specific for establishing a diagnosis of Cushing's disease (pituitary Cushing's)? A. Low-dose dexamethasone suppression B. High-dose dexamethasone suppression C. Twenty-four-hour urinary free cortisol D. Petrosal sinus sampling following corticotropin-releasing hormone stimulation

D. Petrosal sinus sampling following corticotropin-releasing hormone stimulation

Which of the following statements regarding the catecholamines is true? A. They are derived from tryptophan B. They are produced by the zona glomerulosa of the adrenal cortex C. Plasma levels show both diurnal and pulsed variation D. They are excreted in urine primarily as free catecholamines

C. Plasma levels show both diurnal and pulsed variation

Which assay using 24-hour urine is considered the best single screening test for pheochromocytoma? A. Total urinary catecholamines B. VMA C. Homovanillic acid (HVA) D. Metanephrines

D. Metanephrines

Which statement regarding the measurement of urinary catecholamines is true? A. An increased excretion of total urinary catecholamines is specific for pheochromocytoma B. Twenty-four-hour urinary catecholamine assay avoids pulse variations associated with measurement of plasma catecholamines C. Total urinary catecholamine measurement provides greater specificity than measurement of urinary free catecholamines D. Total urinary catecholamines are not affected by exercise

B. Twenty-four-hour urinary catecholamine assay avoids pulse variations associated with measurement of plasma catecholamines

Which metabolite is most often increased in carcinoid tumors of the intestine? A. 5-Hydroxyindolacetic acid (5-HIAA) B. 3-Methoxy-4-hydroxyphenylglycol (MHPG) C. 3-Methoxydopamine D. HVA

A. 5-Hydroxyindolacetic acid (5-HIAA)

Which statement about sample collection for catecholamines and metabolites is true? A. Blood for catecholamines is collected in the usual manner following a 12-hour fast B. Twenty-four-hour urine for vanillylmandelic acid, catecholamines, or metanephrines is collected in 1 mL of boric acid C. Twenty-four-hour urine creatinine should be measured with vanillylmandelic acid, homovanillic acid, or metanephrines D. There is no need to discontinue medications if a 24-hour urine collection is used

C. Twenty-four-hour urine creatinine should be measured with vanillylmandelic acid, homovanillic acid, or metanephrines

Which method is most often used to measure fractionated catecholamines (epinephrine, norepinephrine, and dopamine)? A. Measurement of fluorescence following oxidation by potassium ferricyanide B. Measurement by HPLC with electrochemical detection C. Measure of radioactivity after conversion by catechol-O-methyltransferase (COMT) to tritiated metanephrines D. Measurement by HPLC with fluorescence detection

B. Measurement by HPLC with electrochemical detection

Which of the following statements applies to both measurement of VMA and metanephrines in urine? A. Both can be oxidized to vanillin and measured at 360 nm without interference from dietary compounds B. Both can be measured immunochemically after hydrolysis and derivatization C. Both require acid hydrolysis prior to measurement D. Both can be measured by specific HPLC and MS assays

D. Both can be measured by specific HPLC and MS assays

Urinary HVA is most often assayed to detect: A. Pheochromocytoma B. Neuroblastoma C. Adrenal medullary carcinoma D. Psychiatric disorders such as manic depression

B. Neuroblastoma

Which of the following statements regarding thyroid hormones is true? A. Both protein-bound and free T3 and T4 are physiologically active B. Total T3 and T4 are influenced by the level of thyroxine-binding globulin C. Variation in thyroxine-binding protein levels affects both free T3 and T4 D. An elevated serum total T4 and T3 is diagnostic of hyperthyroidism

B. Total T3 and T4 are influenced by the level of thyroxine-binding globulin

Thyroid hormones are derived from the amino acid: A. Phenylalanine B. Methionine C. Tyrosine D. Histidine

C. Tyrosine

Which of the following conditions will increase total T4 by increasing TBG? A. Acute illness B. Anabolic steroid use C. Nephrotic syndrome D. Pregnancy or estrogens

D. Pregnancy or estrogens

Which statement regarding thyroid hormones is true? A. Circulating levels of T3 and T4 are about equal B. T3 is about 10-fold more active than T4 C. The rate of formation of monoiodotyrosine and diiodotyrosine is about equal D. Most of the T3 present in plasma is from its direct release from thyroid storage sites

B. T3 is about 10-fold more active than T4

Select the most appropriate single screening test for thyroid disease. A. Free thyroxine index B. Total T3 assay C. Total T4 D. TSH assay

D. TSH assay

The serum TSH level is almost absent in: A. Primary hyperthyroidism B. Primary hypothyroidism C. Secondary hyperthyroidism D. Euthyroid sick syndrome

A. Primary hyperthyroidism

Which assay is used to confirm difficult cases of hypothyroidism? A. Free T3 assay B. Free thyroxine index C. Tyrotropin-releasing hormone (TRH) stimulation test D. TBG assay

C. Tyrotropin-releasing hormone (TRH) stimulation test

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

A. Primary hyperthyroidism

Which of the following statements is true regarding reverse T3 (rT3)? A. Formed in the blood by degradation of T4 B. Physiologically active, but less than T3 C. Decreased in euthyroid sick syndrome D. Interferes with the measurement of serum T3

A. Formed in the blood by degradation of T4

A serum thyroid panel reveals an increase in total T4, normal TSH, and normal free T4. What is the most likely cause of these results? A. Primary hyperthyroidism B. Secondary hyperthyroidism C. Euthyroid with increased thyroxine-binding protein D. Subclinical hypothyroidism

C. Euthyroid with increased thyroxine-binding protein

Which statement about TSH and T4 in early pregnancy is correct? A. TSH and thyroid hormones fall B. TSH falls and thyroid hormones rise C. TSH and thyroid hormones both rise D. TSH rises and thyroid hormones fall

B. TSH falls and thyroid hormones rise

In which case might a very low plasma TSH result not correlate with thyroid status? A. Euthyroid sick syndrome B. Congenital hypothyroidism C. When TBG is elevated D. After high-dose corticosteroid treatment

D. After high-dose corticosteroid treatment

Which of the following hormones is often decreased by approximately 25% in the serum of pregnant women who have a fetus with Down syndrome? A. Estriol (E3) B. Human chorionic gonadotropin (hCG) C. Progesterone D. Estradiol (E2)

A. Estriol (E3)

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) causes: A. Low serum vasopressin B. Hypernatremia C. Urine osmolality to be lower than plasma D. Low serum electrolytes

D. Low serum electrolytes

Select the hormone which when elevated is associated with galactorrhea, pituitary adenoma, and amenorrhea. A. E2 B. Progesterone C. Follicle-stimulating hormone (FSH) D. Prolactin

D. Prolactin

Zollinger-Ellison (Z-E) syndrome is characterized by great (e.g., 20-fold) elevation of: A. Gastrin B. Cholecystokinin C. Pepsin D. Glucagon

A. Gastrin

Which statement about multiple endocrine neoplasia (MEN) is true? A. It is associated with hyperplasia or neoplasia of at least two endocrine organs B. Insulinoma is always present when the pituitary is involved C. It is inherited as an autosomal recessive disorder D. Plasma hormone levels from affected organs are elevated at least 10-fold

A. It is associated with hyperplasia or neoplasia of at least two endocrine organs

Which statement best describes the relationship between luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in cases of dysmenorrhea? A. Both are usually increased when there is pituitary adenoma B. Increases in both hormones and a decrease in estrogen signal a pituitary cause of ovarian failure C. Both hormones normally peak 1-2 days before ovulation D. In menopause, the LH level at the midcycle peak is higher than the level of FSH

C. Both hormones normally peak 1-2 days before ovulation

Select the main estrogen produced by the ovaries and used to evaluate ovarian function. A. Estriol (E3 ) B. Estradiol (E2 ) C. Epiestriol D. Hydroxyestrone

B. Estradiol (E2 )

When pituitary adenoma is the cause of decreased estrogen production, an increase of which hormone is most frequently responsible? A. Prolactin B. FSH C. LH D. Thyroid-stimulating hormone (TSH)

A. Prolactin

When should progesterone be measured when evaluating an adult female for anovulation? A. At the onset of menses B. During the first 7 days of the menstrual cycle C. At the midcycle just after LH peaks D. At the end of the menstrual cycle

C. At the midcycle just after LH peaks

A female with severe excessive pubic and facial hair growth (hirsutism) should be tested for which of the following hormones? A. Estrogen and progesterone B. Chorionic gonadotropin C. Growth hormone D. Testosterone and dehydroepiandrosterone sulfate

D. Testosterone and dehydroepiandrosterone sulfate

Which set of results is most likely in an adult male with primary testicular failure? A. Increased LH, FSH, and decreased testosterone B. Decreased LH, FSH, and testosterone C. Decreased testosterone, androstenedione, and FSH D. Increased androstenedione, decreased testosterone, and normal FSH

A. Increased LH, FSH, and decreased testosterone

Which set of results is most likely in a female with hypogonadotropic ovarian failure? A. Increased LH, FSH, and estrogen B. Decreased LH, FSH, and estrogen C. Decreased prolactin and estrogen D. Increased LH and FSH, and decreased estrogen

B. Decreased LH, FSH, and estrogen

The onset of menopause is usually associated with what hormone changes? A. Decreased estrogen, testosterone, and androgens B. Decreased estrogen, FSH, LH, and progesterone C. Decreased estrogen and progesterone, and increased LH and FSH D. Decreased estrogen and progesterone, normal LH and FSH

C. Decreased estrogen and progesterone, and increased LH and FSH

Which of the following statements is correct in assessing GH deficiency? A. Pituitary failure may involve one, several, or all adenohypophyseal hormones; but GH deficiency is usually found B. A normal random serum level of GH in a child under 6 years old rules out GH deficiency C. Administration of arginine, insulin, or glucagon will suppress GH release D. GH levels in the blood show little variation within a 24-hour period

A. Pituitary failure may involve one, several, or all adenohypophyseal hormones; but GH deficiency is usually found

Hyperparathyroidism is most consistently associated with: A. Hypocalcemia B. Hypocalciuria C. Hypophosphatemia D. Metabolic alkalosis

C. Hypophosphatemia

Which statement best describes the level of GH in patients with pituitary adenoma associated with acromegaly? A. The fasting GH level is always elevated at least twofold B. Some patients will require a glucose suppression test to establish a diagnosis C. A normal fasting GH level rules out acromegaly D. Patients produce a lower concentration of insulin-like growth factor I (IGF-1) than expected from their GH level

B. Some patients will require a glucose suppression test to establish a diagnosis

The best method of analysis for serum PTH involves using antibodies that detect: A. The amino-terminal fragment of PTH B. Te carboxy-terminal end of PTH C. Both the amino-terminal fragment and intact PTH D. All fragments of PTH as well as intact hormone

C. Both the amino-terminal fragment and intact PTH

Which statement regarding the use of PTH is true? A. Determination of serum PTH level is the best screening test for disorders of calcium metabolism B. PTH levels differentiate primary and secondary causes of hypoparathyroidism C. PTH levels differentiate primary and secondary causes of hypocalcemia D. PTH levels are low in patients with pseudohypoparathyroidism

C. PTH levels differentiate primary and secondary causes of hypocalcemia

Which is normally the most abundant corticosteroid hormone secreted by the adrenal cortex? A. Cortisol B. Dehydroepiandrosterone C. Aldosterone D. Corticosterone

A. Cortisol

Which of the following is most often elevated in hypercalcemia associated with malignancy? A. Parathyroid-derived PTH B. Ectopic PTH C. Parathyroid hormone-related protein (PTHRP) D. Calcitonin

C. Parathyroid hormone-related protein (PTHRP)

Weighthich of the following conditions is characterized by primary hyperaldosteronism caused by adrenal adenoma, carcinoma, or hyperplasia? A. Cushing's syndrome B. Addison's disease C. Conn's syndrome D. Pheochromocytoma

C. Conn's syndrome

Which of the following statements about cortisol in Cushing's syndrome is true? A. Twenty-four-hour urinary free cortisol is a more sensitive test than plasma total cortisol B. Patients with Cushing's disease show pronounced diurnal variation in serum cortisol C. Free cortisol is increased by a high-serum cortisol-binding protein concentration D. An elevated serum total cortisol level is diagnostic of Cushing's syndrome

A. Twenty-four-hour urinary free cortisol is a more sensitive test than plasma total cortisol

Which of the following statements regarding adrenal cortical dysfunction is true? A. Patients with Cushing's syndrome usually have hyperkalemia B. Cushing's syndrome is associated with glucose intolerance C. Addison's disease is associated with hypernatremia D. Addison's disease is caused by elevated levels of cortisol

B. Cushing's syndrome is associated with glucose

Which of the following is the most common cause of Cushing's syndrome? A. Pituitary adenoma B. Adrenal hyperplasia C. Overuse of corticosteroids D. Ectopic adrenocorticotropic hormone (ACTH) production by tumors

C. Overuse of corticosteroids

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

A. Excess secretion of pituitary ACTH

Which of the following statements about the aminotransferases (AST and ALT) is true? A. Isoenzymes of AST and ALT are not found in humans B. Both transfer an amino group to α-ketoglutarate C. Both require NADP+ as a coenzyme D. Both utilize four carbon amino acids as substrates

B. Both transfer an amino group to α-ketoglutarate

Select the products formed from the forward reaction of AST. A. Alanine and α-ketoglutarate B. Oxaloacetate and glutamate C. Aspartate and glutamine D. Glutamate and NADH

B. Oxaloacetate and glutamate

Select the products formed from the forward reaction of ALT. A. Aspartate and alanine B. Alanine and α-ketoglutarate C. Pyruvate and glutamate D. Glutamine and NAD+

C. Pyruvate and glutamate

Select the coupling enzyme used in the kinetic AST reaction of Henry. A. LD B. Malate dehydrogenase C. Glutamate dehydrogenase D. G-6-PD

B. Malate dehydrogenase

What is the purpose of LD in the kinetic method of Henry for AST? A. Forms NADH, enabling the reaction to be monitored at 340 nm B. Rapidly exhausts endogenous pyruvate in the lag phase C. Reduces oxaloacetate, preventing product inhibition D. Generates lactate, which activates AST

B. Rapidly exhausts endogenous pyruvate in the lag phase

Which of the statements below regarding the methods of Henry for AST and ALT is correct? A. Hemolysis will cause positive interference in both AST and ALT assays B. Loss of activity occurs if samples are frozen at -20°C C. The absorbance at the start of the reaction should not exceed 1.0 A D. Reaction rates are unaffected by addition of P-5´-P to the substrate

A. Hemolysis will cause positive interference in both AST and ALT assays

Which of the following statements regarding the naming of transaminases is true? A. Serum glutamic oxaloacetic transaminase (SGOT) is the older abbreviation for ALT B. Serum glutamic pyruvic transaminase (SGPT) is the older abbreviation for AST C. SGPT is the older abbreviation for ALT D. SGOT is the newer abbreviation for AST

C. SGPT is the older abbreviation for ALT

Which statement accurately describes serum transaminase levels in AMI? A. ALT is increased 5- to 10-fold after an AMI B. AST peaks 24-48 hours after an AMI and returns to normal within 4-6 days C. AST levels are usually 20-50 times the upper limit of normal after an AMI D. Isoenzymes of AST are of greater diagnostic utility than the total enzyme level

B. AST peaks 24-48 hours after an AMI and returns to normal within 4-6 days

Which condition gives rise to the highest serum level of transaminases? A. Acute hepatitis B. Alcoholic cirrhosis C. Obstructive biliary disease D. Diffuse intrahepatic cholestasis

A. Acute hepatitis

In which liver disease is the DeRitis ratio (ALT:AST) usually greater than 1.0? A. Acute hepatitis B. Chronic hepatitis C. Hepatic cirrhosis D. Hepatic carcinoma

A. Acute hepatitis

Which of the following liver diseases produces the highest levels of transaminases? A. Hepatic cirrhosis B. Obstructive jaundice C. Hepatic cancer D. Alcoholic hepatitis

C. Hepatic cancer

Which of the following statements regarding transaminases is true? A. ALT is often increased in muscular disease, pancreatitis, and lymphoma B. ALT is increased in infectious mononucleosis, but AST is usually normal C. ALT is far more specific for liver diseases than is AST D. Substrate depletion seldom occurs in assays of serum from hepatitis cases

C. ALT is far more specific for liver diseases than is AST

Select the most sensitive marker for alcoholic liver disease. A. GLD B. ALT C. AST D. γ-Glutamyltransferase (GGT)

D. γ-Glutamyltransferase (GGT)

Which enzyme is least useful in differentiating necrotic from obstructive jaundice? A. GGT B. ALT C. 5' Nucleotidase D. LD

D. LD

Which of the following statements about the phosphatases is true? A. They hydrolyze adenosine triphosphate and related compounds B. They are divided into two classes based upon pH needed for activity C. They exhibit a high specificity for substrate D. They are activated by Pi

B. They are divided into two classes based upon pH needed for activity

Which of the following statements regarding ALP is true? A. In normal adults, the primary tissue source is fast-twitch skeletal muscle B. Geriatric patients have a lower serum ALP than other adults C. Serum ALP levels are lower in children than in adults D. Pregnant women have a higher level of serum ALP than other adults

D. Pregnant women have a higher level of serum ALP than other adults

Which isoenzyme of ALP migrates farthest toward the anode when electrophoresed at pH 8.6? A. Placental B. Bone C. Liver D. Intestinal

C. Liver

Which statement regarding bone-specific ALP is true? A. The bone isoenzyme can be measured immunochemically B. Bone ALP is increased in bone resorption C. Bone ALP is used for the diagnosis of osteoporosis D. There are two distinct bone isoenzymes

A. The bone isoenzyme can be measured immunochemically

Which isoenzyme of ALP is most heat stable? A. Bone B. Liver C. Intestinal D. Placenta

D. Placenta

Which of the following statements regarding ALP is true? A. All isoenzymes of ALP are antigenically distinct and can be identified by specific antibodies B. Highest serum levels are seen in intrahepatic obstruction C. Elevated serum ALP seen with elevated GGT suggests a hepatic source D. When jaundice is present, an elevated ALP suggests acute hepatitis

C. Elevated serum ALP seen with elevated GGT suggests a hepatic source

In which condition would an elevated serum alkaline phosphatase be likely to occur? A. Small cell lung carcinoma B. Hemolytic anemia C. Prostate cancer D. Acute myocardial infarction

A. Small cell lung carcinoma

Which condition is least likely to be associated with increased serum ALP? A. Osteomalacia B. Biliary obstruction C. Hyperparathyroidism and hyperthyroidism D. Osteoporosis

D. Osteoporosis

Which substrate is used in the Bowers-McComb method for ALP? A. p-Nitrophenyl phosphate B. β-Glycerophosphate C. Phenylphosphate D. α-Naphthylphosphate

A. p-Nitrophenyl phosphate

Which of the following buffers is used in the IFCC recommended method for ALP? A. Glycine B. Phosphate C. 2-Amino-2-methyl-1-propanol D. Citrate

C. 2-Amino-2-methyl-1-propanol

A serum ALP level greater than twice the elevation of GGT suggests: A. Misidentification of the specimen B. Focal intrahepatic obstruction C. Acute alcoholic hepatitis D. Bone disease or malignancy

D. Bone disease or malignancy

In which condition is the measurement of acid phosphatase clinically useful? A. Measuring the prostatic isoenzyme to screen for prostate cancer B. Measuring the enzyme in a vaginal swab extract C. The diagnosis of hemolytic anemia D. As a marker for bone regeneration

B. Measuring the enzyme in a vaginal swab extract

Which definition best describes the catalytic activity of amylase? A. Hydrolyzes second α 1-4 glycosidic linkages of starch, glycogen, and other polyglucans B. Hydrolyzes all polyglucans completely to produce glucose C. Oxidatively degrades polysaccharides containing glucose D. Splits polysaccharides and disaccharides by addition of water

A. Hydrolyzes second α 1-4 glycosidic linkages of starch, glycogen, and other polyglucans

Which of the following amylase substrates is recommended by the IFCC? A. Starch B. Maltodextrose C. Maltotetrose D. Blocked maltohepatoside

D. Blocked maltohepatoside

How soon following acute abdominal pain due to pancreatitis is the serum amylase expected to rise? A. 1-2 hours B. 2-12 hours C. 3-4 days D. 5-6 days

B. 2-12 hours

Which of the following statements regarding the diagnosis of pancreatitis is correct? A. Amylase and lipase are as predictive in chronic as in acute pancreatitis B. Diagnostic sensitivity is increased by assaying both amylase and lipase C. Measuring the urinary amylase:creatinine ratio is useful only when patients have renal failure D. Serum lipase peaks several hours before amylase after an episode of acute pancreatitis

B. Diagnostic sensitivity is increased by assaying both amylase and lipase

Which of the following conditions is associated with a high level of S-type amylase? A. Mumps B. Intestinal obstruction C. Alcoholic liver disease D. Peptic ulcers

A. Mumps

Which of the following statements regarding amylase methods is true? A. Requires sulfhydryl compounds for full activity B. Activity will vary depending on the method used C. Amyloclastic methods measure the production of glucose D. Overrange samples are diluted in deionized water

B. Activity will vary depending on the method used

Which of the following statements regarding amylase methods is true? A. Dilution of serum may result in lower than expected activity B. Methods generating NADH are preferred because they have higher sensitivity C. Synthetic substrates can be conjugated to p-nitrophenol (PNP) for a kinetic assay D. The reference range is consistent from method to method

C. Synthetic substrates can be conjugated to p-nitrophenol (PNP) for a kinetic assay

The reference method for lipase uses olive oil as the substrate because: A. Other esterases can hydrolyze triglyceride and synthetic diglycerides B. The reaction product can be coupled to NADH generating reactions C. Synthetic substrates are less soluble than olive oil in aqueous reagents D. Triglyceride substrates cause product inhibition

A. Other esterases can hydrolyze triglyceride and synthetic diglycerides

Which statement about the clinical utility of plasma or serum lipase is true? A. Lipase is not increased in mumps, malignancy, or ectopic pregnancy B. Lipase is not increased as dramatically as amylase in acute pancreatitis C. Increased plasma or serum lipase is specific for pancreatitis D. Lipase levels are elevated in both acute and chronic pancreatitis

A. Lipase is not increased in mumps, malignancy, or ectopic pregnancy

The reference method for serum lipase is based upon: A. Assay of triglycerides following incubation of serum with olive oil B. Rate turbidimetry C. Titration of fatty acids with dilute NaOH following controlled incubation of serum with olive oil D. Immunochemical assay

C. Titration of fatty acids with dilute NaOH following controlled incubation of serum with olive oil

Which of the following enzymes is usually depressed in liver disease? A. Elastase-1 B. GLD C. Pseudocholinesterase D. Aldolase

C. Pseudocholinesterase

The most commonly employed method of assay for plasma or serum lipase is based on: A. Hydrolysis of olive oil B. Rate turbidimetry C. Immunoassay D. Peroxidase coupling

D. Peroxidase coupling

Which enzyme is most likely to be elevated in the plasma of a person suffering from a muscle wasting disorder? A. 5´-Nucleotidase B. Pseudocholinesterase C. Aldolase D. Glutamate dehydrogenase

C. Aldolase

Which enzyme is measured in whole blood? A. Chymotrypsin B. Glucose-6-phosphate dehydrogenase C. Glycogen phosphorylase D. Lipase

B. Glucose-6-phosphate dehydrogenase

All of the following are requirements for a QC material except: A. Long-term stability B. The matrix is similar to the specimens being tested C. The concentration of analytes reflects the clinical range D. Analyte concentration must be independent of the method of assay

D. Analyte concentration must be independent of the method of assay

Examine the Levy-Jennings chart at the bottom of the previous page and identify the QC problem that occurred during the first half of the month. A. Shift B. Trend C. Random error D. Kurtosis

B. Trend

Referring to the Levy-Jennings chart, what is the first day in the month when the run should be rejected and patient results should be repeated? A. Day 6 B. Day 7 C. Day 8 D. Day 9

C. Day 8

Referring to the Levy-Jennings chart, what analytical error is present during the second half of the month? A. Shift B. Trend C. Random error D. Kurtosis

A. Shift

What is the first day in the second half of the month that patient results would be rejected? A. Day 16 B. Day 17 C. Day 18 D. Day 19

B. Day 17

Given the following QC chart, identify the day in which a violation of the R4s QC rule occurs. A. Day 3 B. Day 8 C. Day 10 D. Day 15

D. Day 15

What is the minimum requirement for performing QC for a total protein assay? A. One level assayed every 8 hours B. Two levels assayed within 8 hours C. Two levels assayed within 24 hours D. Three levels assayed within 24 hours

C. Two levels assayed within 24 hours

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 anal

A. Student's t test

Two freezing point osmometers are compared by running 40 paired patient samples one time on each instrument, and the following results are obtained: Instrument / Mean / SD Osmometer A /280 mOsm/kg /3.1 Osmometer B /294 mOsm/kg /2.8 If the critical value for F = 2.8, then what conclusion can be drawn regarding the precision of the two instruments? A. There is no statistically significant difference in precision B. Osmometer A demonstrates better precision that is statistically significant C. Osmometer B demonstrates better precision that is statistically significant D. Precision cannot be evaluated statistically when single measurements are made on samples

A. There is no statistically significant difference in precision

Two methods for total cholesterol are compared by running 40 paired patient samples in duplicate on each instrument. The following results are obtained: Instrument / Mean / SD Method x (reference method) /235 mg/dL /3.8 Method y (candidate method)/ 246 mg/dL /3.4 Assuming the samples are collected and stored in the same way and the analysis done by a technologist who is familiar with both methods, what is the bias of method y? A. 0.4 B. 7.2 C. 10.6 D. 11.0

D. 11.0

When the magnitude of error increases with increasing sample concentration, it is called: A. Constant error B. Proportional error C. Random error D. Bias

B. Proportional error

Which explanation is the best interpretation of the following BUN bias plot? A. The new method consistently overestimates the BUN by a constant concentration B. The new method is greater than the reference method but not by a statistically significant margin C. The new method is lower than the reference method by 5 mg/dL D. The new method is lower than the reference and the magnitude is concentration dependent.

D. The new method is lower than the reference and the magnitude is concentration dependent.

Serum samples collected from hospitalized patients over a 2 week period are split into two aliquots and analyzed for prostate specific antigen (PSA) by two methods. Each sample was assayed by both methods within 30 minutes of collection by a technologist familiar with both methods. The reference method is method × (upper reference limit = 4.0 µg/L). Linear regression analysis was performed by the least-squares method, and results are as follows: Linear Regression/ Correlation Coefficient (r)/ Std Error of Estimates (sy/x) ŷ = 2.10 + 1.01x / 0.984 /0.23 Which statement best characterizes the relationship between the methods? A. There is a significant bias caused by constant error B. There is a significant proportional error C. There is no disagreement between the methods because the correlation coefficient approaches 1.0 D. There is no systematic error, but the random error of the new method is unacceptable

A. There is a significant bias caused by constant error

Which statement best summarizes the relationship between the new BUN method and reference method based upon the following linear regression scatterplot? A. The methods agree very well but show a high standard error of estimate B. There is little or no constant error, but some proportional error C. There will be a significant degree of uncertainty in the regression equation D. There is significant constant and proportional error but little

B. There is little or no constant error, but some proportional error

A new method for BUN is evaluated by comparing the results of 40 paired patient samples to the urease-UV method. Normal and high controls were run on each shift for 5 days, five times per day. The results are as follows: Linear Regression/ Low Control/ High Control ŷ = -0.3 + 0.90x/ -x = 14.2 mg/dL; s=1.24/ -x = 48.6 mg/dL; s=1.12 What is the total analytical error estimate for a sample having a concentration of 50 mg/dL? A. -2.2 mg/dL B. -2.8 mg/dL C. -7.5 mg/dL D.-10.0 mg/dL

C. -7.5 mg/dL

In addition to the number of true negatives (TN), which of the following measurements is needed to calculate specificity? A. True positives B. Prevalence C. False negatives D. False positives

D. False positives

A new tumor marker for ovarian cancer is evaluated for sensitivity by testing serum samples from patients who have been diagnosed by staging biopsy as having malignant or benign lesions. The following results were obtained: Number of malignant patients who are positive for CA 125 = 21 out of 24 Number of benign patients who are negative for CA 125 = 61 out of 62 What is the sensitivity of the new CA 125 test? A. 98.4% B. 95.3% C. 87.5% D. 85.0%

C. 87.5%

A new test for prostate cancer is found to have a sensitivity of 80.0% and a specificity of 84.0%. If the prevalence of prostate cancer is 4.0% in men over 42 years old, what is the predictive value of a positive test result (PV+) in this group? A. 96.0% B. 86.0% C. 32.4% D. 17.2%

D. 17.2%

What measurement in addition to true negatives and prevalence is required to calculate the predictive value of a negative test result (PV-)? A. False negatives B. Variance C. True positives D. False positives

A. False negatives

A laboratory is establishing a reference range for a new analyte and wants the range to be determined by the regional population of adults age 18 and older. The analyte concentration is known to be independent of race and gender. Which is the most appropriate process to follow? A. Determine the mean and standard deviation of the analyte from 40 healthy adults and calculate the ±2s limit B. Measure the analyte in 120 healthy adults and calculate the central 95th percentile C. Measure the analyte in 120 healthy adults and use the lowest and highest as the reference range limits D. Measure the analyte in 60 healthy adults and 60 adults with conditions that affect the analyte concentration; calculate the concentration of least overlap

B. Measure the analyte in 120 healthy adults and calculate the central 95th percentile

When comparing the laboratory's monthly mean to its peer group to determine if bias is present, what statistic is most appropriate? A. F test B. Linear regression analysis C. Correlation coefficient D. Standard deviation index

D. Standard deviation index

Which of the following methods is most useful in order to detect sample misidentification? A. Cumulative summation B. Critical limit C. Delta limit D. Significant change limit

C. Delta limit

Which of the following total quality management tools can be used to calculate the analytical error rate for an analyte in the clinical laboratory? A. LEAN B. Six sigma C. ISO 9000 D. Laboratory information system

B. Six sigma

In which circumstances is a validation study (versus performing routine quality control) required? A. Instrument recalibration B. Source lamp or ion selective electrode change C. Change in reagent lot D. Change in calibrator lot

C. Change in reagent lot

The following plot represents a study of a screening test for malignant prostate cancer using plasma PSA (ng/mL). Te outcome measured was positive cytology results obtained by biopsy. What concentration gives the highest sensitivity with the least number of unnecessary biopsies? A. 2.6 B. 3.6 C. 3.8 D. 5.2

B. 3.6

Creatinine is formed from the: A. Oxidation of creatine B. Oxidation of protein C. Deamination of dibasic amino acids D. Metabolism of purines

A. Oxidation of creatine

Creatinine is considered the substance of choice to measure endogenous renal clearance because: A. The rate of formation per day is independent of body size B. It is completely filtered by the glomeruli C. Plasma levels are highly dependent upon diet D. Clearance is the same for both men and women

B. It is completely filtered by the glomeruli

Which statement regarding creatinine is true? A. Serum levels are elevated in early renal disease B. High serum levels result from reduced glomerular filtration C. Serum creatine has the same diagnostic utility as serum creatinine D. Serum creatinine is a more sensitive measure of renal function than creatinine clearance

B. High serum levels result from reduced glomerular filtration

Which of the following formulas is the correct expression for creatinine clearance? A. Creatinine clearance = U/P X V X 1.73/A B. Creatinine clearance = P/V X U X A/1.73 C. Creatinine clearance = P/V X U X 1.73/A D. Creatinine clearance = U/V X P X 1.73/A

A. Creatinine clearance = U/P X V X 1.73/A

Which of the following conditions is most likely to cause a falsely high creatinine clearance result? A. The patient uses the midstream void procedure when collecting his or her urine B. The patient adds tap water to the urine container because he or she forgets to save one of the urine samples C. The patient does not empty his or her bladder at the conclusion of the test D. The patient empties his or her bladder at the start of the test and adds the urine to the collection

D. The patient empties his or her bladder at the start of the test and adds the urine to the collection

The modification of diet in renal disease (MDRD) formula for calculating eGFR requires which four parameters? A. Urine creatinine, serum creatinine, height, weight B. Serum creatinine, age, gender, race C. Serum creatinine, height, weight, age D. Urine creatinine, gender, weight, age

B. Serum creatinine, age, gender, race

What substance may be measured as an alternative to creatinine for evaluating GFR? A. Plasma urea B. Cystatin C C. Uric acid D. Potassium

B. Cystatin C

Interference from other reducing substances can be partially eliminated in the Jaffe reaction by: A. Measuring the product at 340 nm B. Measuring the product with an electrode C. Measuring the timed rate of product formation D. Performing a sample blank

C. Measuring the timed rate of product formation

Which of the following enzymes allows creatinine to be measured by coupling the creatinine amidohydrolase (creatininase) reaction to the peroxidase reaction? A. Glucose-6-phosphate dehydrogenase B. Creatinine iminohydrolase C. Sarcosine oxidase D. Creatine kinase

C. Sarcosine oxidase

Select the primary reagent used in the Jaffe method for creatinine. A. Alkaline copper II sulfate B. Saturated picric acid and NaOH C. Sodium nitroprusside and phenol D. Phosphotungstic acid

B. Saturated picric acid and NaOH

In which case would eGFR derived from the plasma creatinine likely give a more accurate measure of GFR than measurement of plasma cystatin C? A. Diabetic patient B. Chronic renal failure C. Post-renal transplant D. Chronic hepatitis

C. Post-renal transplant

Which of the following statements is true? A. Cystatin C is measured immunochemically B. The calibrator used for cystatin C is traceable to the National Bureau of Standards calibrator C. Cystatin C assays have a lower coefficient of variation than plasma creatinine D. Enzymatic and rate Jaffe reactions for creatinine give comparable results

A. Cystatin C is measured immunochemically

A sample of amniotic fluid collected for fetal lung maturity studies from a woman with a pregnancy compromised by hemolytic disease of the newborn (HDN) has a creatinine of 88 mg/dL. What is the most likely cause of this result? A. The specimen is contaminated with blood B. Bilirubin has interfered with the measurement of creatinine C. A random error occurred when the absorbance signal was being processed by the analyzer D. The fluid is urine from accidental puncture of the urinary bladder

D. The fluid is urine from accidental puncture of the urinary bladder

Which analyte should be reported as a ratio using creatinine concentration as a reference? A. Urinary microalbumin B. Urinary estriol C. Urinary sodium D. Urinary urea

A. Urinary microalbumin

Urea is produced from: A. The catabolism of proteins and amino acids B. Oxidation of purines C. Oxidation of pyrimidines D. The breakdown of complex carbohydrates

A. The catabolism of proteins and amino acids

Urea concentration is calculated from the BUN by multiplying by a factor of: A. 0.5 B. 2.14 C. 6.45 D. 14

B. 2.14

A patient's BUN is 60 mg/dL and serum creatinine is 3.0 mg/dL. These results suggest: A. Laboratory error measuring BUN B. Renal failure C. Prerenal failure D. Patient was not fasting

C. Prerenal failure

Which of the statements below about serum urea is true? A. Levels are independent of diet B. Urea is not reabsorbed by the renal tubules C. High BUN levels can result from necrotic liver disease D. BUN is elevated in prerenal as well as renal failure

D. BUN is elevated in prerenal as well as renal failure

Urinary urea measurements may be used for calculation of: A. Glomerular filtration B. Renal blood flow C. Nitrogen balance D. All of these options

C. Nitrogen balance

BUN is determined electrochemically by coupling the urease reaction to measurement of: A. Potential with a urea-selective electrode B. The timed rate of increase in conductivity C. The oxidation of ammonia D. Carbon dioxide

B. The timed rate of increase in conductivity

In the ultraviolet enzymatic method for BUN, the urease reaction is coupled to a second enzymatic reaction using: A. AST B. Glutamate dehydrogenase C. Glutamine synthetase D. Alanine aminotransferase (ALT)

B. Glutamate dehydrogenase

Which product is measured in the coupling step of the urease-UV method for BUN? A. CO2 B. Dinitrophenylhydrazine C. Diphenylcarbazone D. NAD+

D. NAD+

Which enzyme deficiency is responsible for phenylketonuria (PKU)? A. Phenylalanine hydroxylase B. Tyrosine transaminase C. p-Hydroxyphenylpyruvic acid oxidase D. Homogentisic acid oxidase

A. Phenylalanine hydroxylase

Which of the following conditions is classified as a renal-type aminoaciduria? A. Fanconi syndrome B. Wilson's disease C. Hepatitis D. Homocystinuria

A. Fanconi syndrome

Which aminoaciduria results in the overflow of branched chain amino acids? A. Hartnup's disease B. Alkaptonuria C. Homocystinuria D. Maple syrup urine disease

D. Maple syrup urine disease

In addition to phenylketonuria, maple syrup urine disease, and homocystinuria, what other aminoaciduria can be detected by tandem MS? A. Alkaptonuria B. Hartnup disease C. Citrullinemia D. Cystinuria

C. Citrullinemia

Of the methods used to measure amino acids, which is capable of measuring fatty acids simultaneously? A. Tandem-mass spectroscopy B. High-performance liquid chromatography C. Capillary electrophoresis D. Two-dimensional thin-layer chromatography

A. Tandem-mass spectroscopy

Blood ammonia levels are usually measured in order to evaluate: A. Renal failure B. Acid-base status C. Hepatic coma D. Gastrointestinal malabsorption

C. Hepatic coma

Enzymatic measurement of ammonia requires which of the following substrates and coenzymes? Substrate / Coenzyme A. α-Ketoglutarate / NADH B. Glutamate / NADH C. Glutamine / ATP D. Glutamine / NAD+

A. α-Ketoglutarate / NADH

Which statement about ammonia is true? A. Normally, most of the plasma ammonia is derived from peripheral blood deamination of amino acids B. Ammonia-induced coma can result from salicylate poisoning C. Hepatic coma can result from Reye's syndrome D. High plasma ammonia is usually caused by respiratory alkalosis

C. Hepatic coma can result from Reye's syndrome

SITUATION: A sample for ammonia assay is taken from an IV line that had been capped and injected with lithium heparin (called a heparin lock). The sample is drawn in a syringe containing lithium heparin, and immediately capped and iced. The plasma is separated and analyzed within 20 minutes of collection, and the result is 50 µg/dL higher than one measured 4 hours before. What is the most likely explanation of these results? A. Significantly greater physiological variation is seen with patients having systemic, hepatic, and gastrointestinal diseases B. The syringe was contaminated with ammonia C. One of the two samples was collected from the wrong patient D. Stasis of blood in the line caused increased ammonia

D. Stasis of blood in the line caused increased ammonia

Uric acid is derived from the: A. Oxidation of proteins B. Catabolism of purines C. Oxidation of pyrimidines D. Reduction of catecholamines

B. Catabolism of purines

Which of the following conditions is associated with hyperuricemia? A. Renal failure B. Chronic liver disease C. Xanthine oxidase deficiency D. Paget's disease of the bone

A. Renal failure

Orders for uric acid are legitimate stat requests because: A. Levels above 10 mg/dL cause urinary tract calculi B. Uric acid is hepatotoxic C. High levels induce aplastic anemia D. High levels cause joint pain

A. Levels above 10 mg/dL cause urinary tract calculi

Which uric acid method is associated with negative bias caused by reducing agents? A. Uricase coupled to the Trinder reaction B. Ultraviolet uricase reaction coupled to catalase and alcohol dehydrogenase reactions C. Measurement of the rate of absorbance decrease at 290 nm after addition of uricase D. Phosphotungstic acid using a protein-free filtrate

A. Uricase coupled to the Trinder reaction

Kjeldahl's procedure for total protein is based upon the premise that: A. Proteins are negatively charged B. The pKa of proteins is the same C. The nitrogen content of proteins is constant D. Proteins have similar tyrosine and tryptophan content

C. The nitrogen content of proteins is constant

Upon which principle is the biuret method based? A. The reaction of phenolic groups with CuIISO4 B. Coordinate bonds between Cu+2 and carbonyl and imine groups of peptide bonds. C. The protein error of indicator effect producing color when dyes bind protein D. The reaction of phosphomolybdic acid with protein

B. Coordinate bonds between Cu+2 and carbonyl and imine groups of peptide bonds.

Which statement about the biuret reaction for total protein is true? A. It is sensitive to protein levels below 0.1 mg/dL B. It is suitable for urine, exudates, and transudates C. Polypeptides and compounds with repeating imine groups react D. Hemolysis will not interfere

C. Polypeptides and compounds with repeating imine groups react

Which of the following protein methods has the highest analytical sensitivity? A. Refractometry B. Folin-Lowry C. Turbidimetry D. Direct ultraviolet absorption

B. Folin-Lowry

Which of the following statements regarding proteins is true? A. Total protein and albumin are about 10% higher in ambulatory patients B. Plasma total protein is about 20% higher than serum levels C. Albumin normally accounts for about one-third of the cerebrospinal fluid total protein D. Transudative serous fluid protein is about two-thirds of the serum total protein

A. Total protein and albumin are about 10% higher in ambulatory patients

Hyperalbuminemia is caused by: A. Dehydration syndromes B. Liver disease C. Burns D. Gastroenteropathy

A. Dehydration syndromes

High serum total protein but low albumin is usually seen in: A. Multiple myeloma B. Hepatic cirrhosis C. Glomerulonephritis D. Nephrotic syndrome

A. Multiple myeloma

Which of the following conditions is most commonly associated with an elevated level of total protein? A. Glomerular disease B. Starvation C. Liver failure D. Malignancy

D. Malignancy

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

B. Bromcresol purple (BCP)

Which of the following factors is most likely to cause a falsely low result when using the BCG dye-binding assay for albumin? A. The presence of penicillin B. An incubation time of 120 seconds C. The presence of bilirubin D. Lipemia

A. The presence of penicillin

At pH 8.6, proteins are _________ charged and migrate toward the _________. A. Negatively, anode B. Positively, cathode C. Positively, anode D. Negatively, cathode

A. Negatively, anode

Electrophoretic movement of proteins toward the anode will decrease by increasing the: A. Buffer pH B. Ionic strength of the buffer C. Current D. Voltage

B. Ionic strength of the buffer

At pH 8.6, the cathodal movement of γ globulins is caused by: A. Electroendosmosis B. Wick flow C. A net positive charge D. Cathodal sample application

A. Electroendosmosis

Which of the following conditions will prevent any migration of proteins across an electrophoretic support medium such as agarose? A. Using too high a voltage B. Excessive current during the procedure C. Loss of contact between a buffer chamber and the medium D. Evaporation of solvent from the surface of the medium

C. Loss of contact between a buffer chamber and the medium

Which of the following proteins has the highest pI? A. Albumin B. Transferrin C. Ceruloplasmin D. IgG

D. IgG

Which of the following is one advantage of high-resolution (HR) agarose electrophoresis over lower-current electrophoresis? A. High-resolution procedures detect monoclonal and oligoclonal bands at a lower concentration B. A smaller sample volume is used C. Results are obtained more rapidly D. Densitometric scanning of HR gels is more accurate

A. High-resolution procedures detect monoclonal and oligoclonal bands at a lower concentration

Which of the following conditions is associated with "β-γ bridging"? A. Multiple myeloma B. Malignancy C. Hepatic cirrhosis D. Rheumatoid arthritis

C. Hepatic cirrhosis

Which of the following proteins migrates in the β region at pH 8.6? A. Haptoglobin B. Orosomucoprotein C. Antichymotrypsin D. Transferrin

D. Transferrin

Which support medium can be used to determine the molecular weight of a protein? A. Cellulose acetate B. Polyacrylamide gel C. Agar gel D. Agarose gel

B. Polyacrylamide gel

Which of the following stains is used for lipoprotein electrophoresis? A. Oil Red O B. Coomassie Brilliant Blue C. Amido Black D. Ponceau S

A. Oil Red O

Which of the following serum protein electrophoresis results suggests an acute inflammatory process? Albumin/ α-1 /α2 /β /γ A. Decreased, Increased, Decreased, Normal, Normal B. Normal, Increased, Normal, Increased, Increased C. Decreased, Increased, Increased, Normal, Normal D. Increased, Increased, Increased, Increased, Increased

C. Decreased, Increased, Increased, Normal, Normal

The electrophoretic pattern shown in the following densitometric tracing most likely indicates: A. α1-Antitrypsin deficiency B. Infection C. Nephrosis D. Systemic sclerosis

A. α1-Antitrypsin deficiency

Which of the following conditions is usually associated with an acute inflammatory pattern? A. Myocardial infarction (MI) B. Malignancy C. Rheumatoid arthritis D. Hepatitis

A. Myocardial infarction (MI)

What is the clinical utility of testing for serum prealbumin? A. Low levels are associated with increased free cortisol B. High levels are an indicator of acute inflammation C. Serial low levels indicate compromised nutritional status D. Levels correlate with glomerular injury in patients with diabetes mellitus

C. Serial low levels indicate compromised nutritional status

Which serum protein should be measured in a patient suspected of having Wilson's disease? A. Hemopexin B. Alpha-1 antitrypsin C. Haptoglobin D. Ceruloplasmin

D. Ceruloplasmin

A patient with hemolytic-uremic syndrome associated with septicemia has a haptoglobin level that is normal, although the plasma free hemoglobin is elevated and hemoglobinuria is present. Which test would be more appropriate than haptoglobin to measure this patient's hemolytic episode? A. Hemopexin B. Alpha-1 antitrypsin C. C-reactive protein D. Transferrin

A. Hemopexin

Quantitative determination of Hgb A2 and Hgb F are best performed by: A. High-performance liquid chromatography B. Alkali denaturation C. Electrophoresis D. Direct bichromatic spectrophotometry

A. High-performance liquid chromatography

Select the correct order of Hgb migration on agarose or cellulose acetate at pH 8.6. A. - C→F→S→A + B. - S→C→A→F + C. - C→S→F→A + D. - S→F→A→C +

C. - C→S→F→A +

Which of the following abnormal types of Hgb migrates to the same position as Hgb S on agarose or cellulose acetate at pH 8.6? A. Hgb C B. Hgb DPunjab C. Hgb OArab D. Hgb E

B. Hgb DPunjab

Select the correct order of Hgb migration on citrate agar at pH 6.2. A. - F→S→C→A + B. - F→A→S→C + C. - A→S→F→C + D. - A→C→S→F +

B. - F→A→S→C +

Which Hgb is a β-δ chain hybrid and migrates to the same position as Hgb S at pH 8.6? A. Hgb CHarlem B. HgbLepore C. Hgb GPhiladelphia D. Hgb DPunjab

B. HgbLepore

Which Hgb separates from Hgb S on citrate (acid) agar, but not agarose or cellulose acetate? A. Hgb DPunjab B. Hgb E C. Hgb CHarlem (Georgetown) D. Hgb OArab

A. Hgb DPunjab

Which statement best describes immunofixation electrophoresis (IEF)? A. Proteins are separated by electrophoresis followed by overlay of monospecific anti-immunoglobulins B. Proteins react with monospecific antisera followed by electrophoresis C. Antisera are electrophoresed, then diffused against patient's serum D. Serum is electrophoresed; the separated immunoglobulins diffuse against specific antisera placed into troughs

A. Proteins are separated by electrophoresis followed by overlay of monospecific anti-immunoglobulins

In double immunodiffusion reactions, the precipitin band is: A. Invisible before the equivalence point is reached B. Concave to the protein of greatest molecular weight C. Closest to the well containing the highest level of antigen D. Located in an area of antibody excess

B. Concave to the protein of greatest molecular weight

Which of the following statements regarding the identification of monoclonal proteins by IFE is true? A. The monoclonal band must be present in the γ region B. When testing for a monoclonal gammopathy, both serum and urine must be examined C. A diagnosis of monoclonal gammopathy is based upon quantitation of IgG, IgA, and IgM D. A monoclonal band always indicates a malignant disorder

B. When testing for a monoclonal gammopathy, both serum and urine must be examined

Which of the following statements regarding paraproteins is true? A. Oligoclonal banding is seen in the CSF of greater than 90% of multiple sclerosis cases B. The Bence-Jones protein heat test is confirmatory for monoclonal light chains C. Light chains found in urine are always derived from monoclonal protein D. The IgA band is usually cathodal to the IgG precipitin band

A. Oligoclonal banding is seen in the CSF of greater than 90% of multiple sclerosis cases

Which statement regarding IFE is true? A. Serum containing a monoclonal protein should have a κ:λ ratio of 0.5 B. A monoclonal band seen with monospecific antiserum should not be visible in the lane where polyvalent antiserum or sulfosalicylic acid was added C. CSF should be concentrated 50- to100-fold before performing IFE D. When oligoclonal bands are seen in the CSF, they must also be present in serum to indicate multiple sclerosis

C. CSF should be concentrated 50- to100-fold before performing IFE

Which test is the most sensitive in detecting early monoclonal gammopathies? A. High-resolution serum protein electrophoresis B. Urinary electrophoresis for monoclonal light chains C. Capillary electrophoresis of serum and urine D. Serum-free light chain immunoassay

D. Serum-free light chain immunoassay

Which test is the most useful way to evaluate the response to treatment for multiple myeloma? A. Measure of total immunoglobulin B. Measurement of 24-hour urinary light chain concentration (Bence-Jones protein) C. Capillary electrophoresis of M-protein recurrence D. Measurement of serum-free light chains

D. Measurement of serum-free light chains

Which of the following is more commonly associated with a nonmalignant form of monoclonal gammopathy (MGUS)? A. Bone marrow plasma cells comprise 20% of nucleated cells B. Monoclonal protein (M-protein) concentration is 3.5 g/dL C. M-protein is IgG D. Age greater than 60 at the time of monoclonal protein discovery

D. Age greater than 60 at the time of monoclonal protein discovery

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 +

C. - Chylomicrons →β→pre-β→α +

Capillary electrophoresis differs from agarose gel electrophoresis in which respect? A. A stationary support is not used B. An acidic buffer is used C. A low voltage is used D. Electroendosmosis does not occur

A. A stationary support is not used

Following ultracentrifugation of plasma, which fraction correlates with pre-β lipoprotein? A. Very low-density lipoprotein (VLDL) B. Low-density lipoprotein (LDL) C. High-density lipoprotein (HDL) D. Chylomicrons

A. Very low-density lipoprotein (VLDL)

Select the lipoprotein fraction that carries most of the endogenous triglycerides. A. VLDL B. LDL C. HDL D. Chylomicrons

A. VLDL

The protein composition of HDL is what percentage by weight? A. Less than 2% B. 25% C. 50% D. 90%

C. 50%

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

A. Apoprotein A-I

In familial β dyslipoproteinemia (formerly type III hyperlipoproteinemia), which lipoprotein accumulates? A. Chylomicrons B. VLDL C. IDL D. VLDL

C. IDL

Which of the following mechanisms accounts for the elevated plasma level of β lipoproteins seen in familial hypercholesterolemia (formerly type II hyperlipoproteinemia)? A. Hyperinsulinemia B. ApoB-100 receptor defect C. ApoC-II activated lipase deficiency D. ApoE3 deficiency

B. ApoB-100 receptor defect

Which of the following conditions is most consistently associated with secondary hypercholesterolemia? A. Hypothyroidism B. Pancreatitis C. Oral contraceptive therapy D. Diabetes mellitus

A. Hypothyroidism

Which enzyme deficiency is most commonly associated with familial hypertriglyceridemia associated with fasting plasma cholomicrons (formerly type I hyperlipoproteinemia)? A. β Glucocerebrosidase deficiency B. Post-heparin-activated lipoprotein lipase deficiency C. Apo-B deficiency D. Apo-C-III deficiency

B. Post-heparin-activated lipoprotein lipase deficiency

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

D. Apoprotein A-I deficiency

Which of the following statements is correct? A. Both HDL and LDL are homogenous B. There are several subfractions of LDL but not HDL C. There are several subfractions of HDL but not LDL D. There are several subfractions of both HDL and LDL

D. There are several subfractions of both HDL and LDL

What is the most appropriate fasting procedure when a lipid study of triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol tests are ordered? A. 8 hours; nothing but water allowed B. 10 hours; water, smoking, coffee, tea (no sugar or cream) allowed C. 12 hours; nothing but water allowed D. 16 hours; water, smoking, coffee, tea (no sugar or cream) allowed

C. 12 hours; nothing but water allowed

What is the lipid testing protocol for adults recommended by the National Cholesterol Education Program (NCEP) to evaluate risk for atherosclerosis beginning at age 20? A. Total cholesterol, fasting or nonfasting every year B. Total cholesterol, fasting, every 2 years C. Lipid profile, fasting, every 5 years D. LDL cholesterol, fasting, every 2 years

C. Lipid profile, fasting, every 5 years

Treatment recommendations for patients with coronary heart disease are based upon measurement of which analyte? A. HDL cholesterol B. Apo-B100 C. LDL cholesterol D. Total cholesterol

C. LDL cholesterol

What is the HDL cholesterol cutpoint recommend by NCEP? A. <30 mg/dL B. <40 mg/dL C. <30 mg/dL for males and < 40 mg/dL for females D. <45 mg/dL for males and < 50 mg/dL for females

B. <40 mg/dL

An EDTA blood sample is collected from a nonfasting person for a CBC. The physician collected the sample from the femoral vein because venipuncture from the arm was unsuccessful. He called the lab 15 minutes after the sample arrived and requested a lipid study including triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol. Which test results should be used to evaluate the patient's risk for coronary artery disease? A. Total cholesterol and LDL cholesterol B. LDL cholesterol and triglyceride C. Total cholesterol and HDL cholesterol D. Total cholesterol and triglyceride

C. Total cholesterol and HDL cholesterol

Which of the following diseases is caused by a deficiency of sphingomyelinase? A. Gaucher disease B. Fabry disease C. Niemann-Pick disease D. Tay-Sachs disease

C. Niemann-Pick disease

Which method is considered the candidate reference method for triglyceride measurement? A. Glycerol kinase-ultraviolet B. CDC modification of van Handel and Zilversmit C. Hantzsch condensation D. Glycerol kinase coupled to peroxidase

B. CDC modification of van Handel and Zilversmit

Which of the following enzymes is common to all enzymatic methods for triglyceride measurement? A. Glycerol phosphate oxidase B. Glycerol phosphate dehydrogenase C. Glycerol kinase D. Pyruvate kinase

C. Glycerol kinase

Select the reagent needed in the coupling enzyme reaction used to generate a colored product in the cholesterol oxidase method for cholesterol. A. Cholestahexaene B. H2O2 C. 4-Aminoantipyrine D. Cholest-4-ene-3-one

C. 4-Aminoantipyrine

What is the purpose of the saponification step used in the Abell-Kendall method for cholesterol measurement? A. Remove phospholipids B. Reduce sterol molecules structurally similar to cholesterol C. Convert cholesterol esters to free cholesterol D. Remove proteins that can interfere with color formation

C. Convert cholesterol esters to free cholesterol

Which of the following methods for HDL cholesterol is the reference method? A. Manganese-heparin B. Magnesium-phosphotungstate C. Magnesium-dextran D. Ultracentrifugation

D. Ultracentrifugation

Cholesterol esterase is used in enzymatic assays to: A. Oxidize cholesterol to form peroxide B. Hydrolyze fatty acids bound to the third carbon atom of cholesterol C. Separate cholesterol from apoproteins A-I and A-II by hydrolysis D. Reduce NAD+ to NADH

B. Hydrolyze fatty acids bound to the third carbon atom of cholesterol

Which of the following reagents is used in the direct HDL cholesterol method? A. Sulfated cyclodextrin B. Magnesium sulfate and dextran sulfate C. Anti-apoA-I D. Manganese heparin

A. Sulfated cyclodextrin

What do "direct" or homogenous methods for LDL cholesterol assay have in common? A. They are inaccurate when plasma triglyceride is above 250 mg/dL B. All use a detergent to facilitate selective reactivity with reagent enzymes C. All use monoclonal antibodies to apo A1 and C D. All are free of interference from abnormal lipoproteins

B. All use a detergent to facilitate selective reactivity with reagent enzymes

Lipoprotein (a), or Lp(a), is significant when elevated in serum because it: A. Is an independent risk factor for atherosclerosis B. Blocks the clearance of VLDLs C. Displaces apo-AI from HDLs D. Is linked closely to a gene for obesity

A. Is an independent risk factor for atherosclerosis

Which type of dietary fatty acid is not associated with an increase in serum LDL cholesterol production? A. Monounsaturated trans fatty acids B. Saturated fatty acids C. Monounsaturated cis fatty acids D. Monounsaturated trans Ω-9 fatty acids

C. Monounsaturated cis fatty acids

SITUATION: A lipemic specimen collected from an adult after a 12-hour fast was assayed for total cholesterol, triglycerides, and HDL cholesterol using a direct HDL method. Following are the results: Total cholesterol = 220 mg/dL HDL cholesterol = 40 mg/dL Triglyceride = 420 mg/dL The physician requests an LDL cholesterol assay after receiving the results. How should the LDL cholesterol be determined? A. Dilute the specimen 1:10 and repeat all tests; calculate LDL cholesterol using the Friedewald equation B. Perform a direct LDL cholesterol assay C. Ultracentrifuge the sample and repeat the HDL cholesterol on the infranate. Use the new result to calculate the LDL cholesterol D. Repeat the HDL cholesterol using the manganese heparin precipitation method. Use the new result to calculate the LDL cholesterol

B. Perform a direct LDL cholesterol assay

A person has a fasting triglyceride level of 240 mg/dL. The physician wishes to know the patient's non-HDL cholesterol level. What cholesterol fractions should be measured? A. Total cholesterol and HDL cholesterol B. Total cholesterol and LDL cholesterol C. HDL cholesterol and LDL cholesterol D. Total cholesterol and chylomicrons

A. Total cholesterol and HDL cholesterol

Which of the following statements regarding enzymatic reactions is true? A. The enzyme shifts the equilibrium of the reaction to the right B. The enzyme alters the equilibrium constant of the reaction C. The enzyme increases the rate of the reaction D. The enzyme alters the energy difference between reactants and products

C. The enzyme increases the rate of the reaction

An international unit (IU) of enzyme activity is the quantity of enzyme that: A. Converts 1 µmol of substrate to product per liter B. Forms 1 mg of product per deciliter C. Converts 1 µmol of substrate to product per minute D. Forms 1 µmol of product per liter

C. Converts 1 µmol of substrate to product per minute

Which of the following statements describes a nonkinetic enzyme assay? A. Initial absorbance is measured followed by a second reading after 5 minutes B. Absorbance is measured at 10-second intervals for 100 seconds C. Absorbance is monitored continuously for 1 minute using a chart recorder D. Reflectance is measured from a xenon source lamp pulsing at 60 Hz

A. Initial absorbance is measured followed by a second reading after 5 minutes

Which statement about enzymes is true? A. An enzyme alters the Gibb's free energy of the reaction B. Enzymes cause a reaction with a positive free energy to occur spontaneously C. An enzyme's natural substrate has the highest Km D. A competitive inhibitor will alter the apparent Km of the reaction

D. A competitive inhibitor will alter the apparent Km of the reaction

Which substrate concentration is needed to achieve zero-order conditions? A. Greater than 99 × Km B. [S] = Km C. Less than 10 × Km D. [S] = 0

A. Greater than 99 × Km

Which of the following statements is true? A. Apoenzyme + prosthetic group = holoenzyme B. A coenzyme is an inorganic molecule required for activity C. Cofactors are as tightly bound to the enzyme as prosthetic groups D. All enzymes have optimal activity at pH 7.00

A. Apoenzyme + prosthetic group = holoenzyme

Which of the following statements about enzymatic reactions is true? A. NADH has absorbance maximas at 340 and 366 nm B. Enzyme concentration must be in excess to achieve zero-order kinetics C. Rate is proportional to substrate concentration in a zero-order reaction D. Accumulation of the product increases the reaction rate

A. NADH has absorbance maximas at 340 and 366 nm

Which of the following enzymes is considered most tissue specific? A. Creatine kinase (CK) B. Amylase C. Alkaline phosphatase (ALP) D. Alcohol dehydrogenase (ADH)

D. Alcohol dehydrogenase (ADH)

The increase in the level of serum enzymes used to detect cholestatic liver disease is caused mainly by: A. Enzyme release from dead cells B. Leakage from cells with altered membrane permeability C. Decreased perfusion of the tissue D. Increased production and secretion by cells

D. Increased production and secretion by cells

Which of the following enzymes is activated by calcium ions? A. CK B. Amylase C. ALP D. LD

B. Amylase

Which statement about methods for measuring LD is true? A. The formation of pyruvate from lactate (forward reaction) generates NAD+ B. The pyruvate-to-lactate reaction proceeds at about twice the rate as the forward reaction C. The lactate-to-pyruvate reaction is optimized at pH 7.4 D. The negative-rate reaction is preferred

B. The pyruvate-to-lactate reaction proceeds at about twice the rate as the forward reaction

Which of the following enzymes is a transferase? A. ALP B. CK C. Amylase D. LD

B. CK

Which condition produces the highest elevation of serum lactate dehydrogenase? A. Pernicious anemia B. Myocardial infarction C. Acute hepatitis D. Muscular dystrophy

A. Pernicious anemia

In which condition is the LD most likely to be within normal limits? A. Hepatic carcinoma B. Pulmonary infarction C. Acute appendicitis D. Crush injury

C. Acute appendicitis

In the Oliver-Rosalki method, the reverse reaction is used to measure CK activity. The enzyme(s) used in the coupling reactions is (are): A. Hexokinase and G-6-PD B. Pyruvate kinase and LD C. Luciferase D. Adenylate kinase

A. Hexokinase and G-6-PD

The LD pleural fluid:serum ratio for a transudative fluid is usually: A. 3:1 or higher B. 2:1 C. 1:1 D. 1:2 or less

D. 1:2 or less

In the Oliver-Rosalki method for CK, adenosine monophosphate (AMP) is added to the substrate in order to: A. Inhibit adenylate kinase B. Block the oxidation of glutathione C. Increase the amount of ADP that is available D. Block the action of diadenosine pentaphosphate

A. Inhibit adenylate kinase

In which type of liver disease would you expect the greatest elevation of LD? A. Toxic hepatitis B. Alcoholic hepatitis C. Cirrhosis D. Acute viral hepatitis

A. Toxic hepatitis

Which of the following conditions will interfere with the measurement of LD? A. Slight hemolysis during sample collection B. Storage at 4°C for 3 days C. Storage at room temperature for 16 hours D. Use of plasma collected in heparin

A. Slight hemolysis during sample collection

Which substance is used in the CK assay to activate the enzyme? A. Flavin adenine dinucleotide (FAD) B. Imidazole C. N-acetylcysteine D. Pyridoxyl-5´-phosphate

C. N-acetylcysteine

Which of the following statements regarding total CK is true? A. Levels are unaffected by strenuous exercise B. Levels are unaffected by repeated intramuscular injections C. Highest levels are seen in Duchenne's muscular dystrophy D. The enzyme is highly specific for heart injury

C. Highest levels are seen in Duchenne's muscular dystrophy

SITUATION: A physician calls to request a CK on a sample already sent to the laboratory for coagulation studies. The sample is 2-hour-old citrated blood and has been stored at 4°C. The plasma shows very slight hemolysis. What is the best course of action and the reason for it? A. Perform the CK assay on the sample because no interferent is present B. Reject the sample because it is slightly hemolyzed C. Reject the sample because it has been stored too long D. Reject the sample because the citrate will interfere

D. Reject the sample because the citrate will interfere

SITUATION: A specimen for CK performed on an automated analyzer using an optimized Oliver-Rosalki method gives an error flag indicating substrate depletion. The sample is diluted 1:2 and 1:4 by the serial dilution technique and reassayed. After correcting for the dilution, the results are as follows: 1:2 Dilution = 3,000 IU/L 1:4 Dilution = 3,600 IU/L Dilutions are made a second time and assayed again but give identical results. What is the most likely explanation? A. The serum became contaminated prior to making the 1:4 dilution B. The wrong pipet was used to make one of the dilutions C. An endogenous competitive inhibitor is present in the serum D. An error has been made in calculating the enzyme activity of one of the two dilutions

C. An endogenous competitive inhibitor is present in the serum

Which of the following statements regarding the clinical use of CK-MB (CK-2) is true? A. CK-MB becomes elevated before myoglobin after an AMI B. CK-MB levels are usually increased in cases of cardiac ischemia C. CK-MB is more specific than myoglobin D. An elevated CK-MB is always accompanied by an elevated total CK

C. CK-MB is more specific than myoglobin

A patient's CK-MB is reported as 18 µg/L and the total CK as 560 IU/L. What is the CK relative index (CKI)? A. 0.10% B. 3.2% C. 10.0% D. 30.0%

B. 3.2%

In a nonmyocardial as opposed to a myocardial cause of an increased serum or plasma CK-MB, which would be expected? A. An increase in CK-MB that is persistent B. An increase in the percent CK-MB as well as concentration C. The presence of increased TnI D. A more modest increase in total CK than CK-MB

A. An increase in CK-MB that is persistent

What is the typical time course for plasma TnI or TnT following an AMI? A. Abnormal within 3 hours; peaks within 12 hours; returns to normal in 24 hours B. Abnormal within 4 hours; peaks within 18 hours; returns to normal in 48 hours C. Abnormal within 4 hours; peaks within 24 hours; returns to normal in 1 week D. Abnormal within 6 hours; peaks within 36 hours; returns to normal in 5 days

C. Abnormal within 4 hours; peaks within 24 hours; returns to normal in 1 week

Which statement best describes the clinical utility of plasma or serum myoglobin? A. Levels greater than 100 µg/L are diagnostic of AMI B. Levels below 100 µg/L on admission and 2-4 hours postadmission help to exclude a diagnosis of AMI C. Myoglobin peaks after the cardiac troponins but is more sensitive D. The persistence of myoglobin > 110 µg/L for 3 days following chest pain favors a diagnosis of AMI

B. Levels below 100 µg/L on admission and 2-4 hours postadmission help to exclude a diagnosis of AMI

What is the typical time course for plasma myoglobin following an AMI? A. Abnormal before 1 hour; peaks within 3 hours; returns to normal in 8 hours B. Abnormal within 3 hours; peaks within 6 hours; returns to normal in 18 hours C. Abnormal within 2 hours; peaks within 12 hours; returns to normal in 36 hours D. Abnormal within 6 hours; peaks within 24 hours; returns to normal in 72 hours

C. Abnormal within 2 hours; peaks within 12 hours; returns to normal in 36 hours

Which of the following is the most effective serial sampling time for ruling out AMI using both myoglobin and a cardiac specific marker in an emergency department environment? A. Admission and every hour for the next 3 hours or until positive B. Admission, 2 hours, 4 hours, and 6 hours or until positive C. Admission, 3 hours, 6 hours, and a final sample within 12 hours D. Admission and one sample every 8 hours for 48 hours

C. Admission, 3 hours, 6 hours, and a final sample within 12 hours

What is the recommended troponin T and I cutoff (upper limit of normal) for detecting myocardial infarction? A. The cutoff varies with the method of assay but should be no lower than 0.2 ng/mL B. The upper 99th percentile or lowest level that can be measured with 10% CV C. The concentration corresponding to the lowest level of calibrator used D. The highest value fitting under the area of the curve for the 95% confidence interval

B. The upper 99th percentile or lowest level that can be measured with 10% CV

Which of the following cardiac markers is consistently increased in persons who exhibit unstable angina? A. Troponin C B. Troponin T C. CK-MB D. Myoglobin

B. Troponin T

A patient has a plasma myoglobin of 10 µg/L at admission. Three hours later, the myoglobin is 14 µg/L and the troponin I is 0.02 µg/L (reference range 0-0.03 µg/L). These results are consistent with which condition? A. Skeletal muscle injury B. Acute myocardial infarction C. Unstable angina D. No evidence of myocardial or skeletal muscle injury

D. No evidence of myocardial or skeletal muscle injury

A patient has a plasma CK-MB of 14 µg/L at admission and a total CK of 170 IU/L. Serum myoglobin is 130 µg/L and TnI is 1.6 µg/L. Three hours later, the TnI is 3.0 µg/L. Which statement best describes this situation? A. This patient has had an AMI and further testing is unnecessary B. A second CK-MB and myoglobin test should have been performed at 3 hours postadmission to confirm AMI C. These results are consistent with skeletal muscle damage associated with a crush injury that elevated the CK-MB D. Further testing 6-12 hours postadmission is required to establish a diagnosis of AMI

A. This patient has had an AMI and further testing is unnecessary

SITUATION: An EDTA sample for TnI assay gives a result of 0.04 ng/mL (reference range 0-0.03 ng/mL). The test is repeated 3 hours later on a new specimen and the result is 0.06 ng/mL. A third sample collected 6 hours later gives a result of 0.07 ng/mL. The EKG showed no evidence of ST segment elevation (STEMI). What is the most likely explanation? A. A false-positive result occurred due to matrix interference B. Heparin should have been used instead of EDTA, which causes false positives C. The patient has suffered cardiac injury D. The patient has had an ischemic episode without cardiac injury

C. The patient has suffered cardiac injury

Which of the following laboratory tests is a marker for ischemic heart disease? A. CK-MB isoforms B. Myosin light chain 1 C. Albumin cobalt binding D. Free fatty acid binding protein

C. Albumin cobalt binding

Which test becomes abnormal in the earliest stage of the acute coronary syndrome? A. Myosin light chain 1 B. CK-MB isoforms C. Myoglobin D. High-sensitivity C-reactive protein

D. High-sensitivity C-reactive protein

Which statement best describes the clinical utility of B-type natriuretic peptide (BNP)? A. Abnormal levels may be caused by obstructive lung disease B. A positive test indicates prior myocardial damage caused by AMI that occurred within the last 3 months C. A normal test result (<100 pg/mL) helps rule out congestive heart failure in persons with symptoms associated with coronary insufficiency D. A level above 100 pg/mL is not significant if evidence of congestive heart failure is absent

C. A normal test result (<100 pg/mL) helps rule out congestive heart failure in persons with symptoms associated with coronary insufficiency

Which statement best describes the clinical utility of plasma homocysteine? A. Levels are directly related to the quantity of LDL cholesterol in plasma B. High plasma levels are associated with atherosclerosis and increased risk of thrombosis C. Persons who have an elevated plasma homocysteine will also have an increased plasma Lp(a) D. Plasma levels are increased only when there is an inborn error of amino acid metabolism

B. High plasma levels are associated with atherosclerosis and increased risk of thrombosis

Which of the following cardiac markers derived from neutrophils predicts an increased risk for myocardial infarction? A. Phospholipase A2 (PLA2) B. Glycogen phosphorylase BB (GPBB) C. Soluble CD40 ligand (sCD40l) D. Myeloperoxidase (MPO)

D. Myeloperoxidase (MPO)

All Questions Pt.2 Flashcards

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