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CLINICAL CHEMISTRY 2 > Clinical Significance of Enzymes > Flashcards

Clinical Significance of Enzymes Flashcards

1
Q

Pertinent findings in Case study

of 51 y.o JK

A
  • overweight
  • history of AMI and T2DM
  • abdominal discomfort
  • body malaise and bilateral throbbing headache
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2
Q

Enzyme that plays a role in energy production; ATP regeneration

A

Creatine Kinase

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3
Q

storage of high energy Creatine phosphate

A

Creatine Kinase

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4
Q

In contraction cycle, Creatine Phosphate use the production of ATP with?

A

relative constant level of muscle ATP

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5
Q

Creatine + ATP =

A

Creatine Phospate + ADP

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6
Q

Creatine Kinase has highest activity in?

A

Skeletal muscle, heart muscle and brain tissue

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7
Q

Myocardial Infarction, Muscle dystrophy and Rhabdomyolysis

A

Creatine Kinase

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8
Q

Creatine Kinase is considered a sensitive indicator of

A

AMI; Muscular Dystrophy (Duchenne)

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9
Q

CK isoforms

A

CK-MM (muscle); CK-MB (hybrid); CK-BB (brain)

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10
Q

20% CK activity is

A

CK-MB

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11
Q

Highest concentration of CK-BB is found

A

CNS (brain), GIT and uterus during pregnancyn akso urinary bladder, lungs, prostate, colon, stomach, and thyroid

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12
Q

What is the only tissue from which CK-MB enters the serum in significant quantities?

A

Myocardium

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13
Q

Which is more clinically significant isoform of CK?Why?

A

CK-MB isoenzyme - elevated levels come from cardiac tissue (CK- MM can also be found in skeletal muscle so less specific)

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14
Q

Percent that is a good indicator if myocardial damage

A

Greater or equal to 6%

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15
Q

Methods use for measurement in CK? (Clue: E.I.R.I)

A

Electrophoresis, Ion exchange chroma, radioimmunoassay, immunoinhibition methods

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16
Q

Can detech unsatisfactory separation and allows visualization of Adenylate Kinase

A

Electrophoresis in CK

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17
Q

Released from RBCs in hemolyzed samples and causes falsely elevated CK or CK MB

A

Adenylate Kinase

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18
Q

Sources of error in CK

A

Hemolysis, Light, Bedridden, Athletes

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19
Q

True or false: serum should be stored in a dark place because CK is inactivated by light (leading to falsely decreased values)

A

True

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20
Q

Total CK in Makes and Females

A

M: 46 to 171 U/L (0.8 to 2.9 ukat/L)
F: 34 to 145 U/L (0.6 to 2.4 ukat/L)

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21
Q

Catalyzes the interconversion of lactic and pyruvic acids

A

Lactate dehydrogenase

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22
Q

Lesser amounts of LD are found in

A

Lung,smooth muscle and brain

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23
Q

Acts as a Hydrogen donor

A

NAD+ (Nicotinamide adenine dinucleotide)

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24
Q

Diseases with highest levels of (total) LDH

A

Pernicious anemia, hemolytic disorders

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25
Q

Which enzyme can be used as a cardiac biomarker?

A

LDH

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26
Q

For LDH, AST, CK and Troponin I, which is a reliable cardiac biomarker of choice in AMI?

A

Troponin I

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27
Q

Which of the isoenzymes in LDH migrates most quickly toward anode in electrophoresis?

A

LD-1(HHHH)

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28
Q

LD Flipped Pattern

A

In necrosis and IV hemolysis, serum levels of LD-1 increase (greater than LD-2)

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29
Q

About LD-6

A

-migrates cathodic to LD-5
-alcoholic dehydrogenase
-patients w/ arteriosclerotic vascular failure

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30
Q

Hepatic clngestion due to cardiovascular disease

A

LD-5

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31
Q

Liver injury secondary to severe circulatory insufficiency

A

LD-6

32
Q

Erythrocytes contain LDH approx.

A

100-150x in serum

33
Q

LDH activity is _____ in serum regardless of storage temp

A

Unstable

34
Q

Most labile isoenzyme in LDH

A

LD-5

35
Q

Reference range of LDH

A

125-220 U/L

36
Q

Commonly referred to as a transaminase (transfer of an amino group between aspartate and a-keto acids woth the for ation of oxaloaxetate and glutamate)

A

AST

37
Q

End products of Aspartate and A-keto-glutarate

A

Oxaloacetate and Glutamate

38
Q

Keto Acids formed by the reaction are ultimately oxidized by the _______ cycle to provide a source of energy (in AST)

A

Tricarboxylic Acid (TCA) Cycle

39
Q

AST elevations are frequently seen in

A

Pulmonary embolism

40
Q

In liver infection like viral hepatitis: levels may reach

A

100x the ULN

41
Q

In cirrhosis: moderate levels approx

A

4x the ULN

42
Q

AST activity is ____ in serum for 3-4 days at ref temp

A

Stable

43
Q

Reference range of AST

A

5-35 U/L (0.1-0.6 ukat/L)

44
Q

Old name of Alanine Aminotrasnferase

A

Glutamic Pyruvic Transaminase (SGPT)

45
Q

Which is a more liver specific enzyme?

A

ALT

46
Q

Half life of AST and ALT in serum

A

AST: 16 HOURS
ALT: 24 HOURS (elevated levels remain longer)

47
Q

Which liver enzyme is relatively unaffected by hemolysis?

A

ALT

48
Q

Activator used in Alkaline Phosphatase

A

MG+2

49
Q

In ALP, highest concentration is found in the liver in both

A

Sinusoidal, and bile canalicular membranes

50
Q

ALP measurement is used in the evaluation of

A

Hepatobiliary and bone disorders

51
Q

Lithiasis

A

Gallstones

52
Q

Impaired or absent flow of bile to the biliary tract, stagnant bile accumulate in the duct causing congestion and eventual damage to the cells

A

Cholestasis

53
Q

Which disease has the highest elevation of ALP?

A

Paget’s disease (osteititis deformans)

54
Q

Hypersecretion of parathryroid hormone that stimulates the osteoclasts in bone

A

Hyperparathyroidism

55
Q

Responsible for bone resorption

A

Osteoclast

56
Q

Descending order of electrophoresis fraction migration

A

Liver - bone - placental - intestinal

57
Q

ALP is approximately 6x more concentrated in ____ than in _____

A

Erythrocytes, serum

58
Q

Optimal pH of ACP reaction

A

5.0

59
Q

Richest source of ACP

A

Prostate

60
Q

Decrease activity of ACP is due to the

A

Loss of carbon dioxide from serum (resultant increase in pH)

61
Q

Y-glutamyl donor

A

Glutathione

62
Q

Higher elevations of GGT is generally observed in

A

Biliary duct obstruction

63
Q

In hepatic parenchyma: GGT exists in

A

Smooth ER

64
Q

GGT levels will be increased in patient receiving enzyme-inducing drugs

A

Warfarin, Phenobarbitol, and Phenytoin

65
Q

Hemolysis does not interfere with GGT levels because the enzyme is lacking _____

A

Erythrocytes

66
Q

Starch is made up of

A

Amylose and amylopectin

67
Q

Alpha-Amylase attacks only

A

Alpha-glycosidic bonds

68
Q

Ontermediate chains which contain alpha-1,6 branching linkages

A

Dextrins

69
Q

Amylase requires ____ and ___ for its activation

A

Calcium and chloride

70
Q

Major tissue sources of serum amylase

A
  1. Acinar cells of pancrease
    2 Salivary glands
71
Q

Macroamylasemia

A

Amylase molecule combines with immunoglobulins to form a too large complex to be filtered across the glomerulus

72
Q

Effect of morphine and other opiated for
Ain relief before blood sampling in serum amylase

A

Falsely elevated

73
Q

Sphincter of Oddi

A

Muscular opening which leads to the duodenum of small intestine

74
Q

An enzyme that hydrolyzes the ester linkages of fats to produce alcohols and fatty acids

A

Lipase

75
Q

Lipase concentration is found primarily in the

A

Pancreas

76
Q

Preferred enzyme in diagnosing acute pancreatitis

A

Lipase

CLINICAL CHEMISTRY 2 (2 decks)

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