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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• Measurement for diagnosis and management of prostate cancer has largely been replaced by prostate specific antigen (More important test)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
• Elevated 4-10 days after acute myocardial infarction – not clear why (2-6 weeks)
GGT
26
GGT: Clinical Significance
• 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)
27
GGT is highest in: Which conditions?
Intra or post-hepatic biliary obstruction (Cholelithiasis) • Chronic alcohol use (MCV-1st)
28
Hydrolase (Amylase): Greatest Concentration (Location)
Pancreas and Salivary Glands
29
Hydrolase (Amylase): Test interference
Ingestion of alcoholl
30
Hydrolase (Amylase) is the most common lab test in diagnosis of:
Acute pancreatitis
31
Hydrolase (Lipase): MCC of elevation
Acute pancreatitis (Lipase produced only in the pancreas)
32
Hydrolase (Lipase): Patient Prep
8-12 hour fast
33
Hydrolase (Lipase): Clinical Significance
• Acute pancreatitis – more specific than amylase • Levels rise slightly later than amylase, remain high longer (7-10 days)
34
Lactate Dehydrogenase (LDH): Highest Levels (5)
• Liver: acute liver disease • Heart: myocardial infarction • Lung • Skeletal muscle • RBCs: megaloblastic anemia, hemolytic anemias
35
LDH: Clinical Significance
1. Myocardial infarction 2. Liver disease 3. Megaloblastic and hemolytic anemia 4. Progressive Muscular Dystrophy
36
LDH: Myocardial Infarction
• Diagnostic value – when CPK-MB elevation has passed, LDH remains elevated (7-12 days) • Elevations up to 10X higher
37
LDH: Megaloblastic and Hemolytic Anemia (Which anemias have elevations?)
• Not specific enough to be diagnostic • Marked elevations w/ untreated pernicious anemia • Large elevations with folate deficiency anemia
38
Isoenzymes of LDH
• 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
Elevation of LDH-1
(“Red Heart”) • Myocardial infarct* • Hemolytic anemia* • Megaloblastic anemia: B12, folate • Acute renal infarct • Testicular & ovarian cancer
40
Elevation of LDH-3
(“3 cancerous lobes of lung”) • Acute pulmonary infarction • Advanced cancer
41
Elevation of LDH-5
(Liver + Skeletal mm) • Hepatic congestion • Hepatitis (Acute liver disease) • Skeletal muscle injury
42
Elevation of LDH-1 and LDH-5
• Acute MI • Chronic alcoholism with hepatitis & megaloblastic anemia
43
Alanine Aminotransferase (ALT) is predominantly found:
Liver
44
ALT: Test Interference
• Many drugs cause increased ALT levels
45
ALT: Increased values
• Acute viral hepatitis (ALT>AST) • Cirrhosis, alcoholic hepatitis, cholestasis (AST>ALT) • Hepatotoxic drugs
46
ALT: Decreased
• Vitamin B6 deficiency
47
Aspartate Aminotransferase (AST) is found in: (4)
• Liver • Heart • Skeletal muscles • RBCs
48
AST vs. ALT
• AST is more sensitive, but less specific than ALT
49
Common etiologies for elevated AST
• 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
• AST:ALT >1 seen in:
Alcoholic cirrhosis, liver congestion, metastatic tumor
51
AST: ALT <1 seen in:
Acute hepatitis, viral hepatitis, infectious mono
52
AST: Test Interferences (3)
• Non-fasting • Hemolysis • Exercise
53
AST: Increased Values
• 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
Elevation of both AST and ALT high is indicative of:
Liver disease
55
AST/ALT Ratio of 2-6 is commonly associated with
Alcoholic liver disease (chronic liver condition)
56
AST/ALT Ratio: Normal, Abnormal Conditions
• 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
AST & ALT: Myocardial Infarction
• 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
AST & ALT: Viral Hepatitis*
• Commonly see 30-50X upper limit of NL* • Characteristically, ALT higher than AST (Acute)*
59
AST & ALT: Viral Hepatitis*
• Commonly see 30-50X upper limit of NL* • Characteristically, ALT higher than AST (Acute)*
60
AST & ALT: Progressive muscular dystrophy
• AST activity levels increased (CPK) • Usually normal in neurogenic musculoskeletal disease
61
AST & ALT: Other Clinical Significance
• 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
AST & ALT: Other Clinical Significance
• 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
Acute Myocardial Infarction: Signs/Symptoms
• 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
Acute Myocardial Infarction: Lab Findings
• Pattern of enzyme changes support diagnosis • EKG changes diagnostic – 50-75% of cases • Increased ESR • Leukocytosis-left shift
65
Acute Myocardial Infarction: CPK
(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
Acute Myocardial Infarction: AST
(Parallels CPK) • Fairly quick to rise: Peaks at 24-36 hours • Elevated in other diseases
67
Acute Myocardial Infarction: LDH
(Late to the party and late to leave) • Rises later • Peaks 48-60 hours
68
Acute Viral Hepatitis: Types, Symptoms, What Increases
• Type A or B • Tiredness, weakness, followed by jaundice • AST & ALT increase
69
Chronic Hepatitis leads to an increase in: (2)
• Chronic persistent hepatitis – mild increase in AST & ALT • Chronic aggressive hepatitis – more severe increase
70
Obstructive Liver Disease: Extrahepatic
• Stone, spasm, stricture of common bile duct • Carcinoma of head of pancreas
71
Obstructive Liver Disease (Cholestasis): Extrahepatic
• Stone, spasm, stricture of common bile duct • Carcinoma of head of pancreas
72
Obstructive Liver Disease (Cholestasis): Intrahepatic
• Drug toxicity, cancer
73
Liver Disease: Lab Findings (3)
• Elevated ALP and GGT • Normal or slight elevation in transaminases • Possibly elevated LDH
74
Liver Disease: Hepatitis or Cholelithiasis
ALP: Higher in Cholestasis GGT: Higher in Cholestasis ALT: Higher in Hepatitis AST: Higher in Hepatitis LDH: Same (Low Levels)
75
Acute Pancreatitis: Signs/Symptoms
• Severe abdominal pain radiating to back, steadily increasing, occasionally colicky • Fever 100-102 • Nausea • Vomiting
76
Acute Pancreatitis: Lab Findings
• 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
Prostatic Carcinoma: Symptoms
• No symptoms • Bladder outlet symptoms • Hematuria: Painless • Symptoms of metastasis: Bone Pain
78
Prostatic Carcinoma: Lab Findings
• Hematuria • Pyuria • Acid phosphatase: Monitoring tx • Alkaline phosphatase (mets to bone) • PSA: Best
79
Malignancy
• 50% elevated total LDH, LDH-3 isoenzymes
80
Malignancy
• 50% elevated total LDH, LDH-3 isoenzymes
81
Hematopoietic Disease: What elevates?
• LDH-1 elevated in hemolytic states
82
Muscle Disease: What is best for detection/management?
• CPK-3 best test for detection and management

Clinical Pathology II (10 decks)

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