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Clinical Pathology > Plasma Enzymes And Isoenzymes In Diagnosis > Flashcards

Plasma Enzymes And Isoenzymes In Diagnosis Flashcards

1
Q

What is an isoenzyme❓

A
  • Multiple forms of an enzymes from the same genetic origin
  • Same catalytic function
  • Different physical properties such as electrophoretic mobility, solubility or resistance to inhibitor
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2
Q

What is a macroenzyme❓

A
  • A high molecular weight form of a native enzyme with is usually complexed with immunoglobulins
  • Often seen in individuals with autoimmune disease
  • Accumulate in plasma b/c ⬆️molecular masses prevent them from being filtered by the kidneys
  • May result in a diagnostic confusion
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3
Q

What could cause an increase in plasma enzyme levels❓

A
  1. ⬆️proliferation of cells eg in cancer
  2. ⬆️cell damage eg viral hepatitis
  3. ⬆️enzyme synthesis eg microsomal enzyme induction
  4. ⬇️clearance from plasma eg amylase in renal impairment
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4
Q

Mild increases in AST is seen in many illnesses

True or false

A

True

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5
Q

In what conditions would you observe an ⬆️CK

A

Moderate exercise

IM injection

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6
Q

An increase in GGT (gamma-gutamyl transferase) may follow _______ use

A

Phenytoin

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7
Q

An increase in amylase is seen in ❓

A

Renal impairment

Macroamylasaemia

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8
Q

ALP is elevated in children

True or false
Why❓

A

True

Bone growth

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9
Q

GGT is physiologically elevated in men

True or false❓
What other enzyme is❓

A

True

Creatine kinase

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10
Q

Plasma CK is higher in Caucasians that Negroid race

True or false

A

False

Quite the contrary

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11
Q

ALP is higher in pregnancy

True or false

A

True

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12
Q

Mention a few ways you can improve the diagnostic precision of plasma enzyme analysis

A

Isoenzyme determination

Estimation of more than one enzyme eg in AMI check for CKMB and troponin

Serial enzyme estimation

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13
Q

What are the analytical factors that affect plasma enzyme assays❓

A 
Substrate concentration 
Product concentration 
Enzyme concentration 
Reaction temperature 
Reaction pH 
Presence of activators and inhibitors
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14
Q
  1. Creatine Kinase is an enzyme associated with❓
  2. What is it’s molecular weight❓
  3. What is it’s tissue source❓
  4. What is it’s diagnostic significance❓
  5. What is it’s reference range(s)❓
A
  1. ATP regeneration in the muscle
  2. MW- 82,000
  3. Skeletal muscle, heart muscle and brain
  4. It’s an indicator of acute myocardial infarction and muscular dystrophy
  5. M: 15-160 U/L at 37C
    F: 15-130 U/L
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15
Q

What are the three isoenzymes of CK based on electrophoretic mobility❓

Which migrates faster to the anode❓

A
  1. CK-BB (brain type)
  2. CK-MB (hybrid type)
  3. CK-MM (muscle type)

1

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16
Q

CK-MM is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A

Tissue localization:

  1. Heart
  2. Skeletal muscle

Sources of elevation:

  1. Myocardial infarction
  2. Skeletal muscle disorder
  3. Muscular dystrophy
  4. Polymyositis
  5. Hypothyroidism
  6. Malignant hyperthermia
  7. Exercise
  8. IM injection
17
Q

CK-MB is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
  3. What fraction of total CK❓
A
  1. Tissue localization:
    Heart
    Skeletal muscle
2. Sources of elevation:
Myocardial infarction 
Myocardial injury 
Ischemia 
Angina 
Inflammatory heart disease 
Cardiac surgery 
Duchenne-type muscular dystrophy 
Polymyositis

6%

18
Q

CK-BB is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A 
Tissue localization:
Brain 
Bladder 
Lung 
Prostate 
Uterus 
Colon 
Stomach
Thyroid 
Sources of elevation:
CNS shock 
Encephalopathy 
Cerebrovascular accident 
Seizure 
Placental or uterine trauma 
Carcinoma
19
Q
  1. Aspartate aminotransferase is an enzyme associated with❓
  2. It is also known as❓
  3. What is it’s tissue source❓
  4. What is it’s diagnostic significance❓
  5. When is it’s peak❓
  6. What is it’s reference range(s)❓
  7. What could be a source of error❓
A
  1. Transfer of an amino acid group between aspartate and keto acids
  2. SGOT (Serum glutamic-oxaloacetic transaminase)
  3. Liver
    Skeletal muscle
    Cardiac muscle
  4. Hepatocellular disorders eg viral hepatitis, cirrhosis.
    •Skeletal muscle involvement
  5. In AMI:
    begins rise 6-8hrs
    Peak at 24hrs
    Returns to normal in 5days

5-30 U/L at 37C

  1. Hemolysis of sample
20
Q
  1. Alanine aminotransferase is an enzyme associated with❓
  2. It is also known as❓
  3. What is it’s tissue source❓
  4. What is it’s diagnostic significance❓
  5. What is it’s reference range(s)❓
  6. What could be a source of error❓
A
  1. Transfer of an amino group between alanine and alpha ketoglutarate
  2. Glutamate pyruvate aminotransferase
  3. ⬆️conc in Liver; all cells
  4. Hepatocellular disorders

6-37 U/L at 37C

  1. Unaffected by hemolysis
21
Q
  1. Alkaline phosphatase is an enzyme associated with❓
  2. What is it’s tissue source❓
  3. What are it’s isoenzymes❓
  4. How would you identify ALP isoenzymes❓
  5. What is it’s diagnostic significance❓
  6. What is it’s reference range(s)❓
A
  1. Hydrolysis of various phosphomonoesters at an alkaline pH of 9.0 to 10.0
2.
•Liver (sinusoidal and bile canalicular membranes)
•Bone (osteoblasts)
•Placenta 
•Spleen 
•Kidney 
•Intestine 
3. 
liver ALP
bone ALP
placental ALP
intestinal ALP
  1. Electrophoresis (fastest-liver. B, P, I)
    Heat stability 56C, 10min (placental ALP. I, L, B)
    Inhibition by phenylalanine (I and P)
  2. •Hepatobiliary disorders (biliary tract obstruction)
    •Bone disorders (w osteoblast involvement) eg Paget’s disease, osteomalacia, rickets, hyperthyroidism, osteogenic sarcoma
    •Healing bone fractures
    •Physiologic bone growth
    •Pregnancy

30-90 U/L at 30C

22
Q

ALP requires Mg2+ as an activator

True or false

A

True

23
Q

Abnormal fractions of ALP are associated with neoplasms.

  1. What is the frequency of occurrence in cancer patients❓
  2. Which are the most frequently seen❓
  3. What are they referred to as❓
A

3-15%

Regan and Nagao isoenzymes

Carcinoplacental alkaline phosphates

24
Q
  1. Lactate dehydrogenase is an enzyme associated with❓

2. What is it’s tissue source❓

A
  1. Reversible interconversation of pyruvate to lactate
2. Cells of:
Skeletal muscles 
Cardiac muscle 
Liver 
Kidney 
Brain 
Erythrocytes
25
Q

LDH-1 is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A

Heart
RBCs

Myocardial infarction
Hemolytic anemia

26
Q

LDH-2 is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A

Heart
RBCs

Megaloblastic anemia
Acute renal infarct
Hemolysed specimen

27
Q

LDH-3 is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A

Lung
Lymphocytes
Spleen
Pancreas

Pulmonary embolism 
Pneumonia 
Lymphocytosis 
Acute pancreatitis 
Carcinoma
28
Q

LDH-4 is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A

Liver

Hepatic injury

29
Q

LDH-5 is…

  1. Localized in what tissues❓
  2. Increased in what conditions❓
A

Skeletal muscle

Skeletal muscle injury

30
Q
  1. Amylase is an enzyme associated with❓
  2. What is it’s tissue source❓
  3. Molecular weight❓
  4. What is it’s diagnostic significance❓
A
  1. Breaks down starch and glycogen to maltose
  2. Acinar cells of pancreas
    Salivary gland

MW: 50,000-55,000; filtered by glomerulus and seen in urine

  1. Acute pancreatitis
    Severe glomerular impairment
    Diabetic ketoacidosis
    Perforated peptic ulcer
Macroamylasaemia 
Salivary calculi
Acute cholecystitis 
Intestinal obstruction 
Abdominal trauma 
Mumps
31
Q

Acid phosphatase is an enzyme

  1. Found in❓
  2. What is it’s diagnostic significance❓
A 
1. Cells of:
Prostate 
Liver
Erythrocytes 
Platelets 
Bone
  1. Diagnosis and management of prostate cancer (has been replaced by PSA assay)

Clinical Pathology (6 decks)

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