Deck 19: Serum Enzymes

Question 1

What transferase enzyme is involved in the conversion of the stored form of energy to usable energy (adenosine triphosphate [ATP])within cardiac myocytes?

A) Creatine kinase
B) Aspartate aminotransferase
C) Lactate dehydrogenase
D) Troponinase

Answer 1

Creatine kinase

Question 2

A hydrolase enzyme important during digestion that catalyzes the hydrolysis of starches while food is still in the mouth is:

A) lipase.
B) lactate dehydrogenase.
C) S-type amylase.
D) P-type amylase.

Answer 2

S-type amylase.

Question 3

Why is heparin the only acceptable anticoagulant to use when obtaining blood samples for ALP analysis?

A) Heparin contains necessary cofactors for ALP to reach full enzyme activity.
B) Other anticoagulants contain inhibitors of magnesium,which is a required cofactor for ALP activation.
C) Heparin maintains the integrity of the ALP molecule through freeze-thaw cycles.
D) Other anticoagulants bind ALP and reduce its ability to react with substrate in enzyme reactions.

Answer 3

Other anticoagulants contain inhibitors of magnesium,which is a required cofactor for ALP activation.

Question 4

Tartrate-resistant acid phosphatase (TR-ACP)that is present in unhemolyzed serum is synthesized mainly in:

A) erythrocytes.
B) cells of the prostate gland.
C) osteoclasts.
D) hepatocytes.

Question 5

The principal source of serum cholinesterase (CHE)in blood is:

A) liver.
B) skeletal muscle.
C) pancreas.
D) bone.

Question 6

A 37-year-old woman who thinks she might be pregnant visits her physician with a complaint of upper right quadrant pain.Blood samples are obtained.Increased enzyme activity was seen for ALP,AST,LD,and GGT.The ALP was 10 times higher than the upper reference limit.A hepatitis panel and a pregnancy test had negative results.Gel electrophoresis was done to separate ALP isoenzymes,with a dense liver band and what appeared to be a diffuse placental band.If there is not a pregnancy,what is the name given to the observed isoenzyme band that migrates in the same region as the placental isoenzyme?

A) Stable placental isoenzyme
B) Regan isoenzyme
C) S-AMY isoenzyme
D) LD-X isoenzyme

Question 7

A physician orders several laboratory tests on a 55-year-old male patient who is complaining of generalized (all-over)pain,stiffness,fatigue,and headaches.Based on the following serum test results,what is the most likely diagnosis: ALP-significantly increased,GGT- normal?

A) Biliary obstruction
B) Cirrhosis
C) Primary metastatic liver cancer
D) Bone disease

Question 8

At present,the major diagnostic usefulness of tartrate-resistant acid phosphatase type 5b is in its use as a marker of conditions with:

A) a liver involvement.
B) pancreatitis.
C) involvement of the prostate gland.
D) an osteolytic component.

Question 9

Heart tissue contains which of the following CK isoenzymes?

A) MM only
B) MB only
C) BB only
D) MM and MB

Question 10

A 37-year-old woman who thinks she might be pregnant visits her physician with a complaint of upper right quadrant pain.Blood samples are obtained.Increased enzyme activity was seen for ALP,AST,lactate dehydrogenase (LD),and GGT.The ALP was 10 times higher than the upper reference limit.A hepatitis panel and a pregnancy test had negative results.Gel electrophoresis was done to separate ALP isoenzymes,with a dense liver band and what appeared to be a diffuse placental band.If this woman's physician has ruled out pregnancy,activity of what other serum enzyme could be measured to differentiate between hepatobiliary disease and liver disease?

A) NTP
B) ALT
C) Aldolase
D) CHE

Question 11

Increased enzyme activity is typically observed in serum or plasma:

A) only if a genetic abnormality is present.
B) only following mitochondrial damage.
C) following injury or damage to tissue.
D) only if hepatic damage has occurred.

Question 12

A specimen is received in a green top tube (heparin)with a request for alkaline phosphatase analysis.The plasma is separated and the test is performed.How will this specimen type affect the ALP results?

A) There will be no effect,because this is an acceptable specimen for this test.
B) Results will be falsely decreased.
C) Results will be falsely increased.

Question 13

Which of the following products are formed from the forward reaction catalyzed by ALT?

A) Pyruvate and glutamate
B) Aspartate and alanine
C) Oxaloacetate and glutamate
D) Alanine and alpha ketoglutarate

Question 14

Which is the most sensitive enzyme for monitoring chronic alcoholic liver disease?

A) ALP
B) GGT
C) NTP
D) AST

Question 15

Which one of the following enzymes catalyzes the transfer of an amino group to alpha- ketoglutarate with the formation of oxaloacetate and glutamate?

A) Alanine aminotransferase (ALT)
B) Aspartate aminotransferase (AST)
C) Alkaline phosphatase (ALP)
D) 5'-Nucleotidase (NTP)

Question 16

If you were asked by your laboratory director to set up an enzyme profile (group of tests)specifically to assess hepatobiliary (biliary obstruction)disease,which one of the following sets of enzymes would be most appropriate?

A) NTP,ALP,and $\gamma$ -glutamyltransferase (GGT)
B) ALP,GGT,and CK
C) CHE,NTP,and CK
D) LD,CK,ALT,and AST

Question 17

All of the statements below about the clinically significant phosphatases are true except they:

A) catalyze the transfer of amine groups to ketoacids.
B) are divided into two classes based upon pH required for their respective reactions.
C) are isoenzyme forms of the phosphatases.
D) are classified as hydrolases.

Question 18

A 10-year-old girl visits her pediatrician with the complaint of bone pain.Following enzyme studies,these results were obtained: ALP 3.5 higher than upper reference limit; NTP normal.These results are consistent with a diagnosis of:

A) hepatobiliary disease.
B) normal bone growth.
C) viral hepatitis.
D) bone cancer.

Question 19

Activators that are required for normal CK activity include:

A) pyroxidal phosphate and magnesium.
B) magnesium,manganese,and cobalt.
C) magnesium only.
D) NAD and NADH.

Question 20

Which one of the following statements concerning lipase is incorrect?

A) Lipase is localized partly in cells of the pancreas.
B) Following an acute attack of pancreatitis,lipase activity increases within 4 to 8 hours.
C) Lipase is a small enzyme that can be detected in urine.
D) Lipase is considered to be in the hydrolase class of enzymes.

Question 21

A phosphotransferase enzyme that has increased activity when injury,inflammation,or necrosis of skeletal muscle occurs is:

A) ALP.
B) ACP.
C) CK.
D) LD.

Question 22

MATCHING
Match the enzyme with its correct enzyme classification.
Hydrolase

A)Creatine kinase
B)Lactate dehydrogenase
C)Alkaline phosphatase

Question 23

Match the enzyme with its correct substance required for enzyme reaction.Answers may be used more than once,once,or not at all.
Pyridoxal phosphate

A)Creatine kinase
B)Aspartate aminotransferase
C)Amylase

Question 24

Certain muscle relaxants are hydrolyzed by CHE during surgical procedures.If an individual with the atypical (E^a)gene variant is exposed to this relaxant,what would occur?

A) Decreased drug metabolism at the neuromuscular junction with resulting muscle weakness
B) Increased drug metabolism over time with a shortened period of relaxant effect and the patient awakening during surgery
C) Decreased drug metabolism over time with resultant paralysis of respiratory muscles
D) Formation of autoantibodies against choline receptors,with resulting general weakness

Question 25

Which one of the following statements concerning lipase (LPS)is incorrect?

A) When comparing LPS with amylase in diagnosis of acute pancreatitis,amylase is a more specific diagnostic finding.
B) Following an acute attack of pancreatitis,lipase levels elevate within 4 to 8 hours.
C) Lipase is a hydrolase that breaks down glycerol esters of long chain free fatty acids.
D) Most serum lipase activity is derived from pancreas,but gastrointestinal mucosa contributes a small amount.

Question 26

Match the enzyme with its correct substance required for enzyme reaction.Answers may be used more than once,once,or not at all.
Calcium

A)Creatine kinase
B)Aspartate aminotransferase
C)Amylase

Question 27

MATCHING
Match the enzyme with its correct enzyme classification.
Transferase

A)Creatine kinase
B)Lactate dehydrogenase
C)Alkaline phosphatase

Question 28

The recommended assay,because of its specificity and sensitivity for the measurement of the activity of the CK-MB isoenzyme,is the:

A) immunoinhibition assay.
B) polyclonal competitive binding immunoassay.
C) monoclonal sandwich immunoassay.
D) isoenzyme electrophoresis.

Question 29

Which of the following statements is incorrect concerning creatine kinase (CK)?

A) CK catalyzes the conversion of creatine and ADP to creatine phosphate and ATP.
B) Total CK activity can be elevated in skeletal muscle disease.
C) The subunits of CK can combine to form three different CK isoenzymes.
D) CK is classified as a transferase enzyme.

Question 30

A severely hemolyzed serum specimen from an individual with hemolytic anemia is received in the laboratory with a request for total CK and LD enzymes.How will the results of these analyses be falsely affected by the condition of the specimen?

A) LD decreased,CK increased
B) LD increased,CK increased
C) LD decreased,CK decreased
D) LD increased,CK decreased

Question 31

Match the enzyme with its correct substance required for enzyme reaction.Answers may be used more than once,once,or not at all.
Magnesium

A)Creatine kinase
B)Aspartate aminotransferase
C)Amylase

Question 32

MATCHING
Match the enzyme with its correct enzyme classification.
Oxidoreductase

A)Creatine kinase
B)Lactate dehydrogenase
C)Alkaline phosphatase

Question 33

Because your immunoassay analyzer is down for maintenance,you have performed an immunoinhibition assay to determine the relative presence of CK isoenzymes in an individual who has presented with acute upper body pain.The assay reveals a strong activity after inhibition of CK-M subunits using a monoclonal antibody.This result indicates:

A) definitive evidence for an acute cardiac event having occurred.
B) that the individual takes part in strenuous exercise.
C) a nonspecific result due to possible presence of CK-B subunits.
D) definitive evidence for possible gastrointestinal problems.

Question 34

The usefulness of analyzing lipoprotein-associated phospholipase A₂ for the identification of individuals at risk for future cardiovascular events is because of its:

A) release of granules that destabilize complex plaque.
B) ability to transform stable coronary artery plaques to unstable ones.
C) release during inflammatory events such as coronary artery blockage.
D) upregulation in atherosclerotic lesions,particularly complex plaque.