Complete BOC: ASCP prep

1) Following overnight fasting, hypoglycemia in adults is defined as a glucose of:

a. <70 mg/dL (<3.9 mmol/L)

b. <60 mg/dL (<3.3mmol/L)

c. <55 mg/dL (<3.0mmol/L)

d. <45mg/dL (<2.5mmol/L)

d (Diagnosis of hypoglycemia in adults.)

3) The preparation of a patient for standard glucose tolerance testing should include:

a. a high carbohydrate diet for 3 days

b. a low carbohydrate diet for 3 days

c. fasting for 48 hrs. prior to testing

d. bed rest for 3 days

a (GTT diet preparation.)

4) If a fasting glucose was 90 mg/dL, which of the following 2 hr. postprandial glucose result would most closely represent normal glucose metabolism?

a. 55 mg/dL (3.0 mmol/L)

b. 100 mg/dL (5.5 mmol/L)

c. 180 mg/dL (9.9 mmol/L)

d. 260 mg/dL (14.3 mmol/L)

b (Normal 2 hour postprandial value.)

5) A healthy person with a blood glucose of 80 mg/dL (4.4 mmol/L) would have a simultaneously determined cerebrospinal fluid glucose value of:

a. 25 mg/dL (1.4 mmol/L)

b. 50 mg/dL (2.3 mmol/L)

c. 100 mg/dL (5.5 mmol/L)

d. 150 mg/dL (8.3 mmol/L)

b (Ratio of CSF glucose to blood glucose)

6) A 25 yr. old man became nauseated and vomited 90 mins after receiving a standard 75 g carbohydrate dose for an oral glucose tolerance test. The best course of action is to:

a. give the patient a glass of orange juice and continue the test

b. start the test over immediately with a 50 g carbohydrate dose

c. draw blood for glucose and discontinue the test

d. place the patient in a recumbent position, reassure him and continue the test.

c (Use of partial GTT information.)

7) Cerebrospinal fluid for glucose assay should be:

a. refrigerated

b. analyzed immediately

c. heated to 56C

d. stored at room temperature after centrifugation

b (Effect of glycolysis on glucose.)

8) Which of the following 2 hr. postprandial glucose values demonstrates unequivocal hyperglycemia diagnostic for diabetes mellitus?

a. 160 mg/dL (8.8 mmol/L)

b. 170 mg/dL (9.4 mmol/L)

c. 180 mg/dL (9.9 mmol/L)

d. 200 mg/dL (11.0 mmol/L)

d (Unequivocal diagnosis of diabetes mellitus.)

10) A 45 yr. old woman has a fasting serum glucose concentration of 95 mg/dL (5.2 mmol/L) and a 2 hr. postprandial glucose concentration of 105 mg/dL (5.8 mmol/L). The statement which best describes this patient's fasting serum glucose concentration is:

a. normal; reflecting glycogen breakdown by the liver

b. normal; reflecting glycogen breakdown by skeletal muscle

c. abnormal; indication diabetes mellitus

d. abnormal; indicating hypoglycemia

a (Factors contributing to PBS.)

9) Serum levels that define hypoglycemia in pre-term or low birth weight infants are:

a. the same as adults

b. lower than adults

c. the same as a normal full-term infant

d. higher than a normal full-term infant

b (Age effect on glucose.)

11) Pregnant women with symptoms of thirst, frequent urination or unexplained weight loos should have which of the following tests performed?

a. tolbutamide test

b. lactose tolerance test

c. epinephrine tolerance test

d. glucose tolerance test

d (Gestational diabetes.)

12) In the fasting state, the arterial and capillary blood glucose concentration varies from the venous glucose concentration by approximately how many mg/dL (mmol/L)

a. 1 mg/dL (0.05 mmol/L)

b. 5 mg/dL (0.27 mmol/L)

c. 10 mg/dL (0.55 mmol/L)

d. 15 mg/dL (0.82 mmol/L)

b (Arterial vs venous glucose values.)

13) The conversion of glucose or other hexoses into lactate or pyruvate is called:

a. glycogenesis

b. glycogenolysis

c. gluconeogenesis

d. glycolysis

d (Definition of glycolysis)

14) Which of the following values obtained during a glucose tolerance test are diagnostic of diabetes mellitus?

a. 2 hr. specimen = 150 mg/dL (8.3 mmol/L)

b. fasting plasma glucose = 126 mg/dL (6.9 mmol/L)

c. fasting plasma glucose = 110 mg/dL (6.1 mmol/L)

d. 2 hr. specimen = 180 mg/dL (9.9 mmol/L)

b (Diagnosis of diabetes mellitus)

15) The glycated hemoglobin value represents the integrated values of glucose concentration during the preceding:

a. 1-3 weeks

b. 4-5 weeks

c. 6-8 weeks

d. 16-20 weeks

c (Definition of glycated hemoglobin.)

16) Monitoring long term glucose control in patients with adult onset diabetes mellitus can best be accomplished by measuring:

a. weekly fasting 7 am serum glucose

b. glucose tolerance testing

c. 2 hr. postprandial serum glucose

d. hemoglobin A1c

d (Average glucose over time is best predictor.)

18) Total glycosylated hemoglobin levels in a hemolysate reflect the:

a. average blood glucose levels of the past 2-3 months

b. average blood glucose levels for the past week

c. blood glucose level at the time the sample is drawn

d. hemoglobin A1c level at the time the sample is drawn

a (Interpretation of glycated hemoglobin.)

19) Which of the following hemoglobins has glucose-6-phosphate on the amino-terminal valine of the beta chain?

a. S

b. C

c. A2

d. A1c

d (Hgb A1C structure.)

20) A patient with hemolytic anemia will:

a. show a decrease in glycated Hgb value

b. show a increase in glycated Hgb value

c. show little or no change in glycated Hgb value

d. demonstrate an elevated Hgb A1

a (Glycated hemoglobin directly related to life of RBC.)

21) In using ion-exchange chromatographic methods, falsely increased levels of Hgb A1c might be demonstrated in the presence of:

a. iron deficiency anemia

b. pernicious anemia

c. thalassemias

d. Hgb S

d (Interference HgbA1C.)

22) An increase in serum acetone is indicative of a defect in the metabolism of:

a. carbohydrates

b. fats

c. urea nitrogen

d. uric acid

a (Acetone in carbohydrate metabolism.)

23) An infant with diarrhea is being evaluated for a carbohydrate intolerance. His stool yields a positive copper reduction test and a pH of 5.0. It should be concluded that:

a. further tests are indicated

b. results are inconsistent-repeat both tests

c. the diarrhea is not due to carbohydrate intolerance

d. the tests provided no useful information

a (Copper reduction reaction detects many reducing substances.)

24) Blood samples were collected at the beginning of an exercise class and after thirty mins. of aerobic activity. Which of the following would be most consistent with the post exercise sample?

a. normal lactic acid, low pyruvate

b. low lactic acid, elevated pyruvate

c. elevated lactic acid, low pyruvate

d. elevate lactic acid, elevated pyruvate

d (Products of glycolysis.)

25) What is the best method to diagnose lactase deficiency?

a. H2 breath test

b. plasma aldolase level

c. LDH level

d. d-xylose test

a (Diagnosis of lactase deficiency.)

26) The expected blood gas results for a patient in chronic renal failure would match the pattern of:

a. metabolic acidosis

b. respiratory acidosis

c. metabolic alkalosis

d. respiratory alkalosis

a (Reduced excretion of acids.)

27) Severe diarrhea causes:

a. metabolic acidosis

b. metabolic alkalosis

c. respiratory acidosis

d. respiratory alkalosis

a (Excessive loss of bicarbonate.)

29) Factors that contribute to a PCO2 electrode requiring 60-120 seconds to reach equilibrium include the:

a. diffusion characteristics of the membrane

b. actual blood PO2

c. type of calibrating standard

d. potential of the polarizing mercury cell

a (Blood gas instrumentation.)

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

a. respiratory acidosis

b. respiratory alkalosis

c. metabolic acidosis

d. metabolic alkalosis

a (Diseases causing respiratory acidosis.)

31) At blood pH 7.40, what is the ratio of bicarbonate to carbonic acid?

a. 15:1

b. 20:1

c. 25:1

d. 30:1

b (Normal ratio bicarbonate/carbonic acid.)

32) The reference range for the pH of arterial blood measured at 37C is:

a. 7.28-7.34

b. 7.33-7.37

c. 7.35-7.45

d. 7.45-7.50

c (Arterial pH reference range.)

33) A 68 yr. old man arrives in the emergency room with a glucose level of 722 mg/dL (39.7 mmol/L) and serum acetone of 4+ undiluted. An arterial blood gas from this patient is likely to be:

a. low pH

b. high pH

c. low PO2

d. high PO2

a (Interpretation of metabolic acidosis.)

34) A patient is admitted to the emergency room in a state of metabolic alkalosis. Which of the following would be consistent with this diagnosis?

a. high PCO2, increased HCO3

b. low PCO2, increased HCO3

c. high PCO2, decreased HCO3

d. low PCO2, decreased HCO3

a (HCO3 and TCO2 in metabolic alkalosis.)

35) A person suspected of having metabolic alkalosis would have which of the following laboratory findings?

a. CO2 content elevated and PCO2 elevated, pH decreased

b. CO2 content decreased and pH elevated

c. CO2 content decreased, PCO2 decreased and pH decreased

d. CO2 content elevated and pH elevated

d (Levels of CO2 and pH in metabolic alkalosis.)

36) Metabolic acidosis is described as a:

a. increase in CO2 content and PCO2 with a decrease pH

b. decrease in CO2 content with an increased pH

c. increase in CO2 with an increased pH

d. decrease in CO2 content and PCO2 with a decreased pH

d (Component levels in metabolic acidosis.)

38) A common cause of respiratory alkalosis is:

a. vomiting

b. starvation

c. asthma

d. hyperventilation

d (Respiratory alkalosis caused by hyperventilation)

39) Acidosis and alkalosis are best defined as fluctuations in blood pH and CO2 content due to changes in:

a. Bohr effect

b. O2 content

c. bicarbonate buffer

d. carbonic anhydrase

c (Chemical cause of alkalosis and acidosis.)

40) A blood gas sample was sent to the lab on ice, and a bubble was present in the syringe. The blood had been exposed to room air for at least 30 mins. The following change in blood gases will occur:

a. CO2 content increased/PCO2 decreased

b. CO2 content and PO2 increased/pH increased

c. CO2 content and PCO2 decreased/pH decreased

d. PO2 increased/HCO3 decreased

d (Blood gas sample conditions.)

42) Select the test which evaluates renal tubular function:

a. IVP

b. creatinine clearance

c. osmolarity

d. microscopic urinalysis

c (Best test for renal tubular function.)

44) The degree to which the kidney concentrates the glomerular filtrate can be determined by:

a. urine creatine

b. serum creatinine

c. creatinine clearance

d. urine to serum osmolality ratio

d (Kidney concentration determination.)

45) Osmolal gap is the difference between:

a. the ideal and real osmolality values

b. calculated and measured osmolality values

c. plasma and water osmolality values

d. molality and molarity at 4*C

b (Definition of osmolal gap.)

46) The most important buffer pair in plasma is the:

a. phosphate/biphosphate

b. hemoglobin/imidazole

c. bicarbonate/carbonic acid

d. sulfate/bisulfate

c (Most important buffer pair in plasma.)

47) Quantitation of Na+ and K+ by ion selective electrode is the standard method because:

a. dilution is required for flame photometry

b. there is no lipoprotein interference

c. of advances in electrochemistry

d. of the absence of an internal standard

c (Ion selective electrode standard Na K.)

48) What battery of tests is most useful in evaluating an anion gap of 22 mEq/L (22 mmol/L)?

a. Ca++, Mg++, PO-4, and pH

b. BUN, creatinine, salicylate and methanol

c. AST, ALT, LD and amylase

d. glucose, CK, myoglobin, and cryoglobulin

b (Components of anion gap.)

50) Most of the carbon dioxide present in blood is in the form of:

a. dissolved CO2

b. carbonate

c. bicarbonate ion

d. carbonic acid

c (Major component of CO2 in blood.)

51) Serum anion gap is increased in patients with:

a. renal tubular acidosis

b. diabetes alkalosis

c. metabolic acidosis due to diarrhea

d. lactic acidosis

d (Anion gap, lactic acidosis.)

52) The anion gap is useful for quality control of laboratory results for:

a. amino acids and proteins

b. blood gas analyzers

c. Na, K, Cl, and CO2

d. Ca, Ph, Mg

c (Calculation of anion gap.)

53) The buffering capacity of blood is maintained by a reversible exchange process between bicarbonate and:

a. sodium

b. potassium

c. calcium

d. chloride

d (Maintenance of buffering capacity blood.)

54) In respiratory acidosis, a compensatory mechanism is the increase in:

a. respiration rate

b. ammonia formation

c. blood PCO2

d. plasma bicarbonate concentration

d (Compensatory mechanism in respiratory acidosis.)

55) Which of the following electrolytes is the chief plasma cation whose main function is maintaining osmotic pressure?

a. chloride

b. calcium

c. potassium

d. sodium

d (Cation in osmotic pressure.)

56) A potassium level of 6.8 mEq/L (6.8 mmol/L) is obtained. Before reporting the results the first step the technologist should take is to:

a. check the serum for hemolysis

b. rerun the test

c. check the age of the patient

d. do nothing, simply report out the result

a (Effect of hemolysis on K.)

57) The solute that contributes the most to the total serum osmolality is :

a. glucose

b. sodium

c. chloride

d. urea

b (Largest solute in osmolality.)

58) A sweat chloride result of 55 mEq/L (55 mmmol/L) and a sweat sodium of 52 mEq/L (52 mmol/L) were obtained on a patient who has a history of respiratory problems. The best interpretation of these results is:

a. normal

b. normal sodium and an abnormal chloride test should be repeated

c. abnormal results

d. borderline results, the test should be repeated

d (Reference range sweat chloride.)

59) Which of the following is true about direct ion selective electrodes for electrolytes?

a. whole blood specimens are acceptable

b. elevated lipids cause falsely decreased results

c. elevated proteins cause falsely decreased results

d. elevated platelets cause falsely increased results

a (Direct ISE method.)

60) Sodium determination by indirect ion selective electrode is falsely decreased by:

a. elevated chloride levels

b. elevated lipid levels

c. decreased protein levels

d. decreased albumin levels

b (Interferences with indirect ISE methods.)

61) A physician requested that electrolytes on a multiple myeloma patient specimen be run by direct ISE and not indirect ISE because:

a. excess protein binds Na in indirect ISE

b. Na falsely increased by indirect ISE

c. Na is falsely decreased by indirect ISE

d. excess protein reacts with diluent in indirect ISE

c (Interferences with indirect ISE methods.)

62) Which percentage of total serum calcium is nondiffusible protein bound?

a. 80% - 90%

b. 51% - 60%

c. 40% - 50%

d. 10% - 30 %

c (Protein-bound Ca++.)

63) Calcium concentration in the serum is regulated by:

a. insulin

b. parathyroid hormone

c. thyroxine

d. vitamin C

b (Regulation of Ca++.)

64) The regulation of calcium and phosphorous metabolism is accomplished by which of the following glands?

a. thyroid

b. parathyroid

c. adrenal gland

d. pituitary

b (Regulation of Ca++ and P043- metabolism.)

65) A patient has the following results:

increased serum calcium

decreased serum phosphate

increased levels of parathyroid hormone:

This patient most likely has:

a. hyperparathyroidism

b. hypoparathyroidism

c. nephrosis

d. steatorrhea

a (Hyperparathyroidism.)

66) A hospitalized patient is experiencing increased neuromuscular irritability (tetany). Which of the following tests should be ordered immediately?

a. calcium

b. phosphate

c. BUN

d. glucose

a (Tetany and calcium.)

67) Which of the following is most likely to be ordered in addition to serum calcium to determine cause of tetany?

a. magnesium

b. phosphate

c. sodium

d. vitamin D

a (Tetany and magnesium.)

68) A reciprocal relationship exists between:

a. sodium and potassium

b. calcium and phosphate

c. chloride and CO2

d. calcium and magnesium

b (Reciprocal relationship of Ca++ and phosphate.)

69) Fasting serum phosphate concentration is controlled primarily by the:

a. pancreas

b. skeleton

c. parathyroid glands

d. small intestine

c (Regulation of phosphate.)

70) A low concentration of serum phosphorus is commonly found in:

a. patients who are receiving carbohydrate hyperalimentation

b. chronic renal disease

c. hypoparathyroidism

d. patients with pituitary tumors

a (Most common cause of low phosphate.)

72) The primary function of serum albumin in the peripheral blood is to:

a. maintain colloidal osmotic pressure

b. increase antibody production

c. increase fibrinogen formation

d. maintain blood viscosity

a (Physiological feature of albumin.)

74) The first step in analyzing a 24 hr. urine specimen for quantitative urine protein is:

a. subculture the urine for bacteria

b. add the appropriate preservative

c. screen for albumin using a dipstick

d. measure the total volume

d (Basic principle of lab procedure timed urine.)

86) The following data was obtained from a cellulose acetate protein electrophoresis scan:

albumin area = 75 units

gamma globulin area = 30 units

total area = 180 units

total protein = 6.4 g/dL (65 g/L)

The gamma globulin content in g/dL is:

a. 1.1 g/dL (11 g/L)

b. 2.7 g/dL (27 g/L)

c. 3.8 g/dL (38 g/L)

d. 4.9 g/dL (49 g/L)

a (A ratio and proportion procedure is most useful for calculations in which concentrations are not changed, as in this case. Set up a ratio of total area [18] to gamma globulin area [30] in units, and total protein content [6.5] to gamma globulin content [x] in g/dL. Solve for x.)

99) Total iron binding capacity measures the serum iron transporting capacity of:

a. hemoglobin

b. ceruloplasmin

c. transferrin

d. ferritin

c (Transport function of transferrin.)

100) The first step in the quantitation of serum iron is:

a. direct reaction with appropriate chromogen

b. iron saturation of transferrin

c. free iron precipitation

d. separation of iron from transferrin

d (Principle of method of analysis.)

105) To assure an accurate ammonia level result, the specimen should be:

a. incubated at 37 C prior to testing

b. spun and separated immediately, tested as routine

c. spun, separated, iced, and tested immediately

d. stored at room temp. until tested

c (Specimen requirements for analyte stability.)

108) A serum sample demonstrates an elevated result when tested with the Jaffe reaction. This indicates:

a. prolonged hypothermia

b. renal functional impairment

c. pregnancy

d. arrhythmia

b (Creatinine measurement. Kidney function test.)

113) Creatinine clearance is used to estimate the:

a. tubular secretion of creatinine

b. glomerular secretion of creatinine

c. renal glomerular and tubular mass

d. glomerular filtration rate

d (Glomerular filtration rate is estimated by filtration markers such as creatinine clearance.)

114) A blood creatinine value of 5.0 mg/dL (442.0 umol/L) is most likely to be found with which of the following blood values?

a. osmolality: 292 mOsm/kg

b. uric acid: 8 mg/dL

c. urea nitrogen: 80 mg/dL

d. ammonia: 80 ug/dL

c (Abnormal results correlate with abnormal kidney function.)

122) 90% of the copper present in the blood is bound to:

a. transferrin

b. ceruloplasmin

c. albumin

d. cryoglobulin

b (Function of ceruloplasmin.)

130) Hemoglobin S can be separated from hemoglobin D by:

a. electrophoresis on a different medium and acidic pH

b. hemoglobin A2 quantitation

c. electrophoresis at higher voltage

d. Kleihauer-Betke acid elution

a (Comparative mobilities due to structures of Hgb variants.)

131) On electrophoresis at alkaline pH, which of the following is the slowest migrating hemoglobin?

a. Hgb A

b. Hgb S

c. Hgb C

d. Hgb F

c (Comparative mobilities due to structures of Hgb variants.)

142) Kernicterus is an abnormal accumulation of bilirubin in:

a. heart tissue

b. brain tissue

c. liver tissue

d. kidney tissue

b (Definition of kernicterus.)

146) A stool specimen that appears black and tarry should be tested for the presence of :

a. occult blood

b. fecal fat

c. trypsin

d. excess mucus

a (Bleeding from upper GI.)

155) The most specific enzyme test for acute pancreatitis is:

a. acid phosphatase

b. trypsin

c. amylase

d. lipase

d (There is an increase in the serum levels of amylase and lipase in acute pancreatitis. However, the elevated level of lipase persists longer than amylase. Elevated levels of lipase and amylase are seen in other intra- abdominal conditions, but the frequency of elevations is less with lipase than amylase.)

157) Which of the following enzymes catalyzes the conversion of starch to glucose and maltose?

a. malate dehydrogenase

b. amylase

c. creatine kinase

d. isocitric dehydrogenase

b (In the amyloclastic, saccharogenic and chromogenic methods for measurement of amylase, the substrate, starch is converted to glucose and maltose.)

159) A physician suspects his patient has pancreatitis. Which test would be most indicative of this disease?

a. creatinine

b. LD isoenzymes

c. beta-hydroxybutyrate

d. amylase

d (Amylase is present primarily in the pancreas. Pancreatitis results in the release of the enzyme into the serum. Creatinine is a nonprotein nitrogenous substance and is measured for renal function. Beta- hydroxybutyrate is measured for diabetic acidosis and LD isoenzymes are evaluated for disorders involving the heart and liver.)

160) Aspartate amino transferase (AST) is characteristically elevated in diseases of the:

a. liver

b. kidney

c. intestine

d. pancreas

a (Aspartate aminotransferase [AST] is involved in the transfer of an amino group between aspartate and alpha-keto acids. AST is present in several tissues, with its highest concentrations in cardiac tissue, liver and skeletal muscle. Depending on the type of liver disease, the levels may be 100x the upper limits of normal [ULN].)

161) Amino tranferase enzymes catalyze the:

a. exchange of amino groups and sulfhydydryl groups between alpha-amino and sufur-containing acids

b. exchange of amino and keto groups between alpha-amino and alpha-keto acids

c. hydrolysis of amino acids and keto acids

d. reversible transfer of hydrogen from amino acids to coenzyme

b (Aspartate aminotransferase [AST] belongs to the class of transferase enzymes. Specifically, AST catalyzes the transfer of an amino group from aspartate to alpha-ketoglutarate forming oxaloacetate and glutamate.)

162) Aspartate aminotransferase and alanine aminotransferase are both elevated in which of the following diseases?

a. muscular dystrophy

b. viral hepatitis

c. pulmonary emboli

d. infectious mononucleosis

b (The transferases, alanine aminotransferase [ALT] and AST are located primarily in the liver. Elevated serum levels of the enzymes are seen in hepatocellular disorders. The levels may be 100 times the upper limit of normal. The ALT level is usually higher than AST. Increased levels of AST are also seen in infectious mononucleosis and muscular dystrophy, but ALT is not elevated in the clinical disorders.)

163) The greatest activities of serum AST and ALT are seen in which of the following?

a. acute viral hepatitis

b. primary biliary cirrhosis

c. metastatic hepatic cirrhosis

d. alcoholic cirrhosis

a (AST and ALT levels are the highest in acute hepatocellular conditions, specifically acute viral hepatitis. The levels may be 100 times the upper limit of normal. Slight increases of the aminotransferases are seen in cirrhosis and metastatic hepatic carcinoma.)

166) Which of the following clinical disorders is associated with the greatest elevation of lactate dehydrogenase isoenzyme?

a. pneumonia

b. glomerulonephritis

c. pancreatitis

d. pernicious anemia

d (Elevated serum levels of LD up to 50 times the upper limit of normal are seen with pernicious anemia. The ineffective erythropoiesis results in the release of large quantities of LDI and LD2. Increased levels of LDI and LD2 may be seen in renal disease, but the increase is not as great as for pernicious anemia. Slight increases of LD3 are seen in pulmonary conditions and pancreatitis.)

167) The enzyme which exists chiefly in skeletal muscle, heart, and brain, is grossly elevated in active muscular dystrophy, and rises early in myocardial infarction is:

a. lipase

b. transaminase

c. lactate dehydrogenase

d. creatine kinase

d (Creatine kinase [CK] catalyzes the reversible phosphorylation of creatine. The highest levels of the enzyme are found in skeletal muscle, heart muscle and brain tissue. Increased serum enzyme activity is present in diseases involving the listed muscles and tissue. Lipase is measured for acute pancreatitis; the transaminase and lactate dehydrogenase [LD] are not markedly increased in muscular dystrophy.)

168) The enzyme present in almost all tissues that may be separated by electrophoresis into 5 components is:

a. lipase

b. transaminase

c. creatine kinase

d. lactate dehydrogenase

d (Lactate dehydrogenase [LD] catalyzes the interconversion of lactic and pyruvic acids. Electrophoretically, using agarose or cellulose acetate medium, LD can be separated into 5 isoenzymes, LD1-LD5. CK and lipase have 3 isoenzymes; AST has 2.)

169) A common cause of a falsely increased LD1 fraction of lactic dehydrogenase is:

a. specimen hemolysis

b. liver disease

c. congestive heart failure

d. drug toxicity

a (Erythrocytes contain 150 times more LD activity than serum, mostly LD1 and LD2. Rupture of the RBC membranes as in hemolysis will elevate the serum level of the enzyme. LD5 is increased in liver disorders and drug toxicity if the liver is involved.)

170) The presence of which of the following isoenzymes indicates acute myocardial damage?

a. CK-MM

b. CK-MB

c. CK-BB

d. none

b (The 3 CK isoenzymes are CK1 or CKBB, CK2 or CKMB, CK3 or CKMM. CKMB is primarily located in myocardial tissue. Damage to the myocardial will cause an elevation of the CKMB level.)

171) In which of the following conditions would a normal level of creatine kinase be found?

a. acute myocardial infarct

b. hepatitis

c. progressive muscular dystrophy

d. intramuscular injection

b (Creatine kinase [CK] is located in brain tissue and heart and skeletal muscle. Diseases involving the tissue site will increase the level of the enzyme activity. CK activity is not increased in hepatitis.)

172) Of the following diseases, the one most often associated with elevations of LD isoenzymes 4 and 5 on electrophoresis is:

a. liver disease

b. hemolytic anemia

c. myocardial infarction

d. pulmonary edema

a (Elevations of serum LD4 and LD5 fractions are seen in liver and skeletal muscle diseases because the isoenzymes are located in the tissues. LD1 and LD2 are elevated in hemolytic anemia and myocardial infarction. Increased levels of LD3 are observed in pulmonary edema.)

173) When myocardial infarction occurs, the first enzyme to become elevated is:

a. CK

b. LD

c. AST

d. ALT

a (After an acute myocardial infarction [AMI], CK activity increases 4-6 hours after the symptoms, peaks at 12-24 hours and returns to normal within 48-72 hours. AST increases 6-8 hours after the infarction. Elevated levels of LD are noted 12-24 hours after the symptoms. ALT activity does not increase with a AMI.)

174) A scanning of a CK isoenzyme fractionation revealed 2 peaks: A slow cathodic peak (CK-MM) and an intermediate peak (CK-MB). A possible interpretation for this pattern is:

a. brain tumor

b. muscular dystrophy

c. myocardial infarction

d. viral hepatitis

c (Although, CK-MB activity is more specific for the myocardium, CK-MM is present in both the skeletal and heart muscles. An increase of the isoenzyme activity may occur after a AMI. Only one peak would be present for a brain tumor and muscular dystrophy; no peaks would be present for hepatitis since the liver is not a tissue source of CK.)

177) A 10 yr. old child was admitted to pediatrics with an initial diagnosis of skeletal muscle disease. The best confirmatory tests would be:

a. creatine kinase and isocitrate dehydrogenase

b. gamma-glutamyl transferase and alkaline phosphatase

c. aldolase and creatine kinase

d. lactate dehydrogenase and malate dehydrogenase

c (Increased levels of aldolase and CK are seen with skeletal muscle disease. The magnitude of the elevation is dependent on the type of skeletal muscle disease.)

178) In the immunoinhibition phase of the CK-MB procedure:

a. M subunit is inactivated

b. B subunit is inactivated

c. MB is inactivated

d. BB is inactivated

a (In the immunoinhibition technique for CK-MB determination, antibodies are directed against the M and B units of the enzymes. Anti-M inhibits all M activity but not B activity. CK activity is measured before and after inhibition. The activity remaining after inhibition is a result of the B subunit for BE and MB activity.)

179) The presence of increased CK-MB activity on a CK electrophoresis pattern is most likely found in a patient suffering from:

a. acute muscular stress following strenuous exercise

b. malignant liver disease

c. myocardial infarction

d. severe head injury

c (Of the 3 CK isoenzymes, CK-MB is located in the myocardial. The fraction is elevated with an acute myocardial infarction [AMI]. CK-MM is elevated in acute muscular stress following strenuous exercise. CK-BB is increased in brain injury.)

181) Increased serum lactic dehydrogenase activity due to elevation of fast fraction (1 and 2) on electrophoretic separation is caused by:

a. nephrotic syndrome

b. hemolytic anemia

c. pancreatitis

d. hepatic damage

b (The LD1 and LD2 fractions are increased in hemolytic anemia due to the intramedullary hemolysis. LD5 is increased with hepatic damage. LD3 may be increased with acute pancreatitis. The LD isoenzyme pattern in renal disease is very similar to a normal pattern except for the higher absolute values.)

185) What specimen preparation is commonly used to perform the alkaline phosphatase isoenzyme determinations?

a. serum is divided into 2 aliquots, one is frozen and the other is refrigerated

b. serum is divided into 2 aliquots, one is heated at 56 C and the other is unheated

c. no preparation is necessary since the assay used EDTA plasma

d. protein-free filtrate is prepared first

b (The heat activation method of ALP isoenzyme separation involves heating an aliquot of the serum sample at 56 C for 10 minutes. An untreated aliquot of the sample along with the heated one are assayed for ALP activity.)

186) Regan isoenzyme has the same properties as alkaline phosphatase that originates in the:

a. skeleton

b. kidney

c. intestine

d. placenta

d (The Regan isoenzyme is an abnormal ALP isoenzyme. The carcinoplacental ALP has properties similar to the placental enzyme, in that it is also heat stable [65 C, 30 min]. It has been detected in lung, breast, ovarian and colon cancer.)

187) The most heat labile fraction of alkaline phosphatase is obtained from:

a. liver

b. bone

c. intestine

d. placenta

b (The major serum ALP isoenzymes are located in the liver, bone, intestine and placenta. Placenta ALP is most heat stable followed by the intestinal liver and bone fractions in decreasing order of stability.)