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Clinical Pathology II > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Enzyme: Definition

A

• Substance that increases the rate of a reaction without itself being consumed or altered

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2
Q

Increased levels of enzymes in the plasma are due to:

A
  1. Cell leakage: Wear and tear & Disease
  2. Increased synthesis: Drug & Disease
  3. Multiplication of cells which produce the enzyme
    • Active growth (Ie. Pregnancy/childhood)
    • Tissue repair (Ie. Fracture)
    • Malignancies (Ie. Cancer Cells)
  4. Duct obstruction
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3
Q

• Levels of enzyme activity reached in plasma directly related to:

A

Amount of tissue damaged

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4
Q

ACP: Greatest Concentration

A

• Liver, spleen, RBCs, platelets, bone marrow
• Prostate gland (Ie. Older Patient)*

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5
Q

ACP is used to diagnose and stage

A

Prostatic carcinoma

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6
Q

ACP: Test Interferences

A

• Avoid hemolysis (destruction of RBCs)
• Falsely high levels may occur after prostate stimulation

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7
Q

ACP: Increased Levels (4)

A

• Prostatic carcinoma
• Multiple myeloma
• Hyperparathyroidism
• Cancer metastasis to bone

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8
Q

ACP: Clinical Significance

A

• Measurement for diagnosis and management of prostate cancer has largely been replaced by prostate specific antigen (More important test)
• Elevations of ACP found in prostatic cancer with metastases (80%)
• When carcinoma remains localized to prostate gland, normal or slight elevations seen.

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9
Q

Alkaline Phosphatase (ALP) is an enzyme present in:

A

Practically all tissues of the body

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10
Q

ALP: Highest Concentrations

A

-Bone & Liver*
-Others: Billiary tract epithelium, intestinal mucosa, placenta

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11
Q

Regan Isoenzyme is present in about:

A

5-15% of patients (Cancer)

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12
Q

ALP: Interfering factor

A

Recent ingestion of food

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13
Q

ALP: Clinical Significance

A

-Kids (2-3x more than adults)
-Hepatobiliary disease: More elevated in extrahepatic
-Bone Disease: Increased osteoblastic activity
-3rd Trimester of Pregnancy

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14
Q

ALP: Bone Diseases

A

-Highest Levels: Paget’s
-Very High Levels: Bone Cancer
-Moderate Rises: Osteomalacia

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15
Q

Creatine Phosphatase (CPK) is typically measured due to:

A

Myocardial injury (CPK-2 Heart) or Infarct
• CPK-BB (1)
• CPK-MM – normally comprises almost all circulatory CPK enzymes-90% (3)

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16
Q

During myocardial injury/infarct, CPK levels: (Rise, Peak, Normal)

A

Rise 3-6 hours after infarct, peaks at 12-24 hours, normal 12-48 hours after Injury-Quick

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17
Q

CPK-3 Test Interferences (Elevated)

A

• IM injections (CPK 3)
• Strenuous exercise (CPK 3)

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18
Q

CPK Test Interferences: Decreased

A

Early Pregnancy

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19
Q

CPK: Clinical Significance

A

• Muscular dystrophy: CPK 3 (MM) 50x Normal
(May be elevated before clinically apparent)
• Myocardial infarction: Sensitive & Specific CPK-2 (MB)

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20
Q

CPK-1: Clinical Significance (Miscellaneous)

A

• Acute cerebrovascular disease & cerebral ischemia: CPK-1 (BB)
• Epilepsy: CPK-1 (BB)

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21
Q

Gamma glutamyltransferase (GGT) is used to detect:

A

Liver cell dysfunction

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22
Q

GGT very accurately reveals:

A

Cholestasis

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23
Q

GGT elevations usually parallel:

A

ALP (GGT is more sensitive)

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24
Q

GGT can detect:

A

Alcohol ingestion (rapidly rises)

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25
Q

• Elevated 4-10 days after acute myocardial infarction – not clear why (2-6 weeks)

A

GGT

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26
Q

GGT: Clinical Significance

A

• MCC of elevation – active liver disease
• Only moderate elevations in hepatitis
• High elevations – primary or metastatic neoplasms (Liver)
• Small increases – fatty liver, drug intoxication
• Infectious mono and cytomegalovirus (hepatomegaly)

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27
Q

GGT is highest in: Which conditions?

A

Intra or post-hepatic biliary obstruction (Cholelithiasis)
• Chronic alcohol use (MCV-1st)

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28
Q

Hydrolase (Amylase): Greatest Concentration (Location)

A

Pancreas and Salivary Glands

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29
Q

Hydrolase (Amylase): Test interference

A

Ingestion of alcoholl

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30
Q

Hydrolase (Amylase) is the most common lab test in diagnosis of:

A

Acute pancreatitis

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31
Q

Hydrolase (Lipase): MCC of elevation

A

Acute pancreatitis (Lipase produced only in the pancreas)

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32
Q

Hydrolase (Lipase): Patient Prep

A

8-12 hour fast

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33
Q

Hydrolase (Lipase): Clinical Significance

A

• Acute pancreatitis – more specific than amylase
• Levels rise slightly later than amylase, remain high longer (7-10 days)

34
Q

Lactate Dehydrogenase (LDH): Highest Levels (5)

A

• Liver: acute liver disease
• Heart: myocardial infarction
• Lung
• Skeletal muscle
• RBCs: megaloblastic anemia, hemolytic anemias

35
Q

LDH: Clinical Significance

A
  1. Myocardial infarction
  2. Liver disease
  3. Megaloblastic and hemolytic anemia
  4. Progressive Muscular Dystrophy
36
Q

LDH: Myocardial Infarction

A

• Diagnostic value – when CPK-MB elevation has passed, LDH remains elevated (7-12 days)
• Elevations up to 10X higher

37
Q

LDH: Megaloblastic and Hemolytic Anemia
(Which anemias have elevations?)

A

• Not specific enough to be diagnostic
• Marked elevations w/ untreated pernicious anemia
• Large elevations with folate deficiency anemia

38
Q

Isoenzymes of LDH

A

• LDH-5 (liver, skeletal muscle, skin)
• LDH-3 (lung lymphocytes, spleen, pancreas, placenta, 50% malignancy) “3 cancerous lobes of the lung”
• LDH-1 (heart, RBCs, renal cortex, brain) “1 Red Heart”

39
Q

Elevation of LDH-1

A

(“Red Heart”)
• Myocardial infarct*
• Hemolytic anemia*
• Megaloblastic anemia: B12, folate
• Acute renal infarct
• Testicular & ovarian cancer

40
Q

Elevation of LDH-3

A

(“3 cancerous lobes of lung”)
• Acute pulmonary infarction
• Advanced cancer

41
Q

Elevation of LDH-5

A

(Liver + Skeletal mm)
• Hepatic congestion
• Hepatitis (Acute liver disease)
• Skeletal muscle injury

42
Q

Elevation of LDH-1 and LDH-5

A

• Acute MI
• Chronic alcoholism with hepatitis & megaloblastic anemia

43
Q

Alanine Aminotransferase (ALT) is predominantly found:

A

Liver

44
Q

ALT: Test Interference

A

• Many drugs cause increased ALT levels

45
Q

ALT: Increased values

A

• Acute viral hepatitis (ALT>AST)
• Cirrhosis, alcoholic hepatitis, cholestasis (AST>ALT)
• Hepatotoxic drugs

46
Q

ALT: Decreased

A

• Vitamin B6 deficiency

47
Q

Aspartate Aminotransferase (AST) is found in: (4)

A

• Liver
• Heart
• Skeletal muscles
• RBCs

48
Q

AST vs. ALT

A

• AST is more sensitive, but less specific than ALT

49
Q

Common etiologies for elevated AST

A

• Heart (acute MI)-Quick rise
• Liver (hepatitis, cirrhosis, congestion, alcohol or drug-induced liver
dysfunction, space occupying lesions, fatty liver, extrahepatic biliary obstruction)
• Skeletal muscle (acute skeletal muscle injury, myositis, muscular dystrophy, surgery)
• RBCs (hemolysis)

50
Q

• AST:ALT >1 seen in:

A

Alcoholic cirrhosis, liver congestion, metastatic tumor

51
Q

AST: ALT <1 seen in:

A

Acute hepatitis, viral hepatitis, infectious mono

52
Q

AST: Test Interferences (3)

A

• Non-fasting
• Hemolysis
• Exercise

53
Q

AST: Increased Values

A

• Liver: Hepatitis cirrhosis
• Heart: Acute myocardial infarct
• Skeletal muscle: Trauma, surgery, progressive muscular dystrophy, recent convulsions, primary muscle diseases
• RBCs: Acute hemolytic anemia, megaloblastic anemia

54
Q

Elevation of both AST and ALT high is indicative of:

A

Liver disease

55
Q

AST/ALT Ratio of 2-6 is commonly associated with

A

Alcoholic liver disease (chronic liver condition)

56
Q

AST/ALT Ratio: Normal, Abnormal Conditions

A

• In normal individuals: 1.15
• Ratio of 2-6 commonly associated with alcoholic liver disease (chronic liver cond.)
• Acute viral hepatitis usually associated with low ratios (.5-.8)

57
Q

AST & ALT: Myocardial Infarction

A

• AST rises rapidly (4-6 hours after chest pain) 2-10x
• Peak value of AST (24-36 hours) roughly proportional to degree of cardiac damage
• ALT levels within normal limits

58
Q

AST & ALT: Viral Hepatitis*

A

• Commonly see 30-50X upper limit of NL*
• Characteristically, ALT higher than AST (Acute)*

59
Q

AST & ALT: Viral Hepatitis*

A

• Commonly see 30-50X upper limit of NL*
• Characteristically, ALT higher than AST (Acute)*

60
Q

AST & ALT: Progressive muscular dystrophy

A

• AST activity levels increased (CPK)
• Usually normal in neurogenic musculoskeletal disease

61
Q

AST & ALT: Other Clinical Significance

A

• Infectious mono (acute) – values 20X upper limit of normal
• Slight or intermediate elevations w/ intra or extra hepatic cholestasis
• Slight increases: Acute pancreatitis, crush muscle injuries, hemolytic disease
• Slight elevations: Alcohol, certain medications

62
Q

AST & ALT: Other Clinical Significance

A

• Infectious mono (acute) – values 20X upper limit of normal
• Transferase levels in cirrhosis vary with status of cirrhotic process
• Slight or intermediate elevations with intra or extra hepatic cholestasis
• Acute pancreatitis, crush muscle injuries, hemolytic disease, slight increases
• Alcohol, certain medications à slight elevations

63
Q

Acute Myocardial Infarction: Signs/Symptoms

A

• Precordial pain
• Radiating to back, jaw, arm
• Diaphoresis: Excessive sweating
• Sense of impending doom
• Women: nausea, shortness of breath, fatigue, general sense of not feeling*

64
Q

Acute Myocardial Infarction: Lab Findings

A

• Pattern of enzyme changes support diagnosis
• EKG changes diagnostic – 50-75% of cases
• Increased ESR
• Leukocytosis-left shift

65
Q

Acute Myocardial Infarction: CPK

A

(Quick to rise + quick to go away)
• Normal total CPK high negative predictive value
• First enzyme to rise: Peaks at 18-30 hours
• Isoenzyme: CPK-2 (MB)
• Disadvantage: only present for short time

66
Q

Acute Myocardial Infarction: AST

A

(Parallels CPK)
• Fairly quick to rise: Peaks at 24-36 hours
• Elevated in other diseases

67
Q

Acute Myocardial Infarction: LDH

A

(Late to the party and late to leave)
• Rises later
• Peaks 48-60 hours

68
Q

Acute Viral Hepatitis: Types, Symptoms, What Increases

A

• Type A or B
• Tiredness, weakness, followed by jaundice
• AST & ALT increase

69
Q

Chronic Hepatitis leads to an increase in: (2)

A

• Chronic persistent hepatitis – mild increase in AST & ALT
• Chronic aggressive hepatitis – more severe increase

70
Q

Obstructive Liver Disease: Extrahepatic

A

• Stone, spasm, stricture of common bile duct
• Carcinoma of head of pancreas

71
Q

Obstructive Liver Disease (Cholestasis): Extrahepatic

A

• Stone, spasm, stricture of common bile duct
• Carcinoma of head of pancreas

72
Q

Obstructive Liver Disease (Cholestasis): Intrahepatic

A

• Drug toxicity, cancer

73
Q

Liver Disease: Lab Findings (3)

A

• Elevated ALP and GGT
• Normal or slight elevation in transaminases
• Possibly elevated LDH

74
Q

Liver Disease: Hepatitis or Cholelithiasis

A

ALP: Higher in Cholestasis
GGT: Higher in Cholestasis
ALT: Higher in Hepatitis
AST: Higher in Hepatitis
LDH: Same (Low Levels)

75
Q

Acute Pancreatitis: Signs/Symptoms

A

• Severe abdominal pain radiating to back, steadily increasing, occasionally colicky
• Fever 100-102
• Nausea
• Vomiting

76
Q

Acute Pancreatitis: Lab Findings

A

• Amylase – rises within 2-12 hours following episode
• Lipase – advantage over amylase for acute pancreatitis (specific;remain elevated for longer)
• Leukocytosis
• Increased or decreased hematocrit

77
Q

Prostatic Carcinoma: Symptoms

A

• No symptoms
• Bladder outlet symptoms
• Hematuria: Painless
• Symptoms of metastasis: Bone Pain

78
Q

Prostatic Carcinoma: Lab Findings

A

• Hematuria
• Pyuria
• Acid phosphatase: Monitoring tx
• Alkaline phosphatase (mets to bone)
• PSA: Best

79
Q

Malignancy

A

• 50% elevated total LDH, LDH-3 isoenzymes

80
Q

Malignancy

A

• 50% elevated total LDH, LDH-3 isoenzymes

81
Q

Hematopoietic Disease: What elevates?

A

• LDH-1 elevated in hemolytic states

82
Q

Muscle Disease: What is best for detection/management?

A

• CPK-3 best test for detection and management

Clinical Pathology II (10 decks)

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