Clinical chemistry- Enzymes and Cardiac Markers

Question 1

1. 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

Answer 1

C. Converts 1 μmol of substrate to product
per minute

Question 2

2. 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

Answer 2

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

Question 3

3. 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

Answer 3

C. The enzyme increases the rate of the reaction

Question 4

4. 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

Answer 4

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

Question 5

5. 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

Answer 5

A. Greater than 99 × Km

Question 6

6. 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

Answer 6

A. Apoenzyme + prosthetic group = holoenzyme

Question 7

7. 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

Answer 7

A. NADH has absorbance maximas at 340
and 366 nm

Question 8

8. 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

Answer 8

D. Increased production and secretion by cells

Question 9

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

Answer 9

D. Alcohol dehydrogenase (ADH)

Question 10

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

Answer 10

B. Amylase

Question 11

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

Answer 11

B. CK

Question 12

12. 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

Answer 12

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

Question 13

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

Answer 13

A. Pernicious anemia

Question 14

14. 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

Answer 14

C. Acute appendicitis

Question 15

15. 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

Answer 15

D. 1:2 or less

Question 16

16. 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

Answer 16

A. Toxic hepatitis

Question 17

17. 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

Answer 17

A. Slight hemolysis during sample collection

Question 18

18. 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

Answer 18

A. Hexokinase and G-6-PD

Question 19

19. 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

Answer 19

A. Inhibit adenylate kinase

Question 20

20. 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

Answer 20

C. N-acetylcysteine

Question 21

21. 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

Answer 21

C. An endogenous competitive inhibitor is present
in the serum

Question 22

22. 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

Answer 22

D. Reject the sample because the citrate will
interfere

Question 23

23. 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

Answer 23

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

Question 24

24. 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

Answer 24

C. CK-MB is more specific than myoglobin

Question 25

25. 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%

Answer 25

B. 3.2%

Question 26

26. 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

Answer 26

A. An increase in CK-MB that is persistent

Question 27

27. 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

Answer 27

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

Question 28

28. 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

Answer 28

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

Question 29

29. 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

Answer 29

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

Question 30

30. 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

Answer 30

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

Question 31

31. 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

Answer 31

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

Question 32

32. 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

Answer 32

B. Troponin T

Question 33

33. 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

Answer 33

D. No evidence of myocardial or skeletal muscle
injury

Question 34

34. 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

Answer 34

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

Question 35

35. 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

Answer 35

C. The patient has suffered cardiac injury

Question 36

36. 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

Answer 36

C. Albumin cobalt binding

Question 37

37. 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

Answer 37

D. High-sensitivity C-reactive protein

Question 38

38. 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

Answer 38

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

Question 39

39. 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

Answer 39

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

Question 40

40. 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)

Answer 40

D. Myeloperoxidase (MPO)

Question 41

41. 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

Answer 41

B. Both transfer an amino group to α–ketoglutarate

Question 42

42. 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

Answer 42

B. Oxaloacetate and glutamate

Question 43

43. 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+

Answer 43

C. Pyruvate and glutamate

Question 44

44. 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

Answer 44

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

Question 45

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

Answer 45

B. Malate dehydrogenase

Question 46

46. 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

Answer 46

B. Rapidly exhausts endogenous pyruvate in the
lag phase

Question 47

47. 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

Answer 47

C. SGPT is the older abbreviation for ALT

Question 48

48. 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

Answer 48

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

Question 49

49. 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

Answer 49

A. Acute hepatitis

Question 50

50. 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

Answer 50

A. Acute hepatitis

Question 51

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

Answer 51

C. Hepatic cancer

Question 52

52. 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

Answer 52

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

Question 53

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

Answer 53

D. γ-Glutamyltransferase (GGT)

Question 54

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

Answer 54

D. LD

Question 55

55. 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

Answer 55

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

Question 56

56. 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

Answer 56

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

Question 57

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

Answer 57

D. Placental

Question 58

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

Answer 58

C. Liver

Question 59

59. 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

Answer 59

A. The bone isoenzyme can be measured
immunochemically

Question 60

60. 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

Answer 60

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

Question 61

61. 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

Answer 61

A. Small cell lung carcinoma

Question 62

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

Answer 62

D. Osteoporosis

Question 63

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

Answer 63

A. p-Nitrophenyl phosphate

Question 64

64. 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

Answer 64

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

Question 65

65. 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

Answer 65

D. Bone disease or malignancy

Question 66

66. 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

Answer 66

B. Measuring the enzyme in a vaginal swab extract

Question 67

67. 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

Answer 67

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

Question 68

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

Answer 68

D. Blocked maltohepatoside

Question 69

69. 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

Answer 69

B. 2–12 hours

Question 70

70. 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

Answer 70

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

Question 71

71. 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

Answer 71

A. Mumps

Question 72

72. 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

Answer 72

B. Activity will vary depending on the method used

Question 73

73. 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

Answer 73

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

Question 74

74. 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

Answer 74

A. Other esterases can hydrolyze triglyceride and
synthetic diglycerides

Question 75

75. 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

Answer 75

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

Question 76

76. 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

Answer 76

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

Question 77

77. 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

Answer 77

D. Peroxidase coupling

Question 78

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

Answer 78

C. Pseudocholinesterase

Question 79

79. 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

Answer 79

C. Aldolase

Question 80

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

Answer 80

B. Glucose-6-phosphate dehydrogenase