Plasma Enzymes And Isoenzymes In Diagnosis Flashcards
What is an isoenzyme❓
- 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
What is a macroenzyme❓
- 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
What could cause an increase in plasma enzyme levels❓
- ⬆️proliferation of cells eg in cancer
- ⬆️cell damage eg viral hepatitis
- ⬆️enzyme synthesis eg microsomal enzyme induction
- ⬇️clearance from plasma eg amylase in renal impairment
Mild increases in AST is seen in many illnesses
True or false
True
In what conditions would you observe an ⬆️CK
Moderate exercise
IM injection
An increase in GGT (gamma-gutamyl transferase) may follow _______ use
Phenytoin
An increase in amylase is seen in ❓
Renal impairment
Macroamylasaemia
ALP is elevated in children
True or false
Why❓
True
Bone growth
GGT is physiologically elevated in men
True or false❓
What other enzyme is❓
True
Creatine kinase
Plasma CK is higher in Caucasians that Negroid race
True or false
False
Quite the contrary
ALP is higher in pregnancy
True or false
True
Mention a few ways you can improve the diagnostic precision of plasma enzyme analysis
Isoenzyme determination
Estimation of more than one enzyme eg in AMI check for CKMB and troponin
Serial enzyme estimation
What are the analytical factors that affect plasma enzyme assays❓
Substrate concentration Product concentration Enzyme concentration Reaction temperature Reaction pH Presence of activators and inhibitors
- Creatine Kinase is an enzyme associated with❓
- What is it’s molecular weight❓
- What is it’s tissue source❓
- What is it’s diagnostic significance❓
- What is it’s reference range(s)❓
- ATP regeneration in the muscle
- MW- 82,000
- Skeletal muscle, heart muscle and brain
- It’s an indicator of acute myocardial infarction and muscular dystrophy
- M: 15-160 U/L at 37C
F: 15-130 U/L
What are the three isoenzymes of CK based on electrophoretic mobility❓
Which migrates faster to the anode❓
- CK-BB (brain type)
- CK-MB (hybrid type)
- CK-MM (muscle type)
1
CK-MM is…
- Localized in what tissues❓
- Increased in what conditions❓
Tissue localization:
- Heart
- Skeletal muscle
Sources of elevation:
- Myocardial infarction
- Skeletal muscle disorder
- Muscular dystrophy
- Polymyositis
- Hypothyroidism
- Malignant hyperthermia
- Exercise
- IM injection
CK-MB is…
- Localized in what tissues❓
- Increased in what conditions❓
- What fraction of total CK❓
- 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%
CK-BB is…
- Localized in what tissues❓
- Increased in what conditions❓
Tissue localization: Brain Bladder Lung Prostate Uterus Colon Stomach Thyroid
Sources of elevation: CNS shock Encephalopathy Cerebrovascular accident Seizure Placental or uterine trauma Carcinoma
- Aspartate aminotransferase is an enzyme associated with❓
- It is also known as❓
- What is it’s tissue source❓
- What is it’s diagnostic significance❓
- When is it’s peak❓
- What is it’s reference range(s)❓
- What could be a source of error❓
- Transfer of an amino acid group between aspartate and keto acids
- SGOT (Serum glutamic-oxaloacetic transaminase)
- Liver
Skeletal muscle
Cardiac muscle - Hepatocellular disorders eg viral hepatitis, cirrhosis.
•Skeletal muscle involvement - In AMI:
begins rise 6-8hrs
Peak at 24hrs
Returns to normal in 5days
5-30 U/L at 37C
- Hemolysis of sample
- Alanine aminotransferase is an enzyme associated with❓
- It is also known as❓
- What is it’s tissue source❓
- What is it’s diagnostic significance❓
- What is it’s reference range(s)❓
- What could be a source of error❓
- Transfer of an amino group between alanine and alpha ketoglutarate
- Glutamate pyruvate aminotransferase
- ⬆️conc in Liver; all cells
- Hepatocellular disorders
6-37 U/L at 37C
- Unaffected by hemolysis
- Alkaline phosphatase is an enzyme associated with❓
- What is it’s tissue source❓
- What are it’s isoenzymes❓
- How would you identify ALP isoenzymes❓
- What is it’s diagnostic significance❓
- What is it’s reference range(s)❓
- 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
- Electrophoresis (fastest-liver. B, P, I)
Heat stability 56C, 10min (placental ALP. I, L, B)
Inhibition by phenylalanine (I and P) - •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
ALP requires Mg2+ as an activator
True or false
True
Abnormal fractions of ALP are associated with neoplasms.
- What is the frequency of occurrence in cancer patients❓
- Which are the most frequently seen❓
- What are they referred to as❓
3-15%
Regan and Nagao isoenzymes
Carcinoplacental alkaline phosphates
- Lactate dehydrogenase is an enzyme associated with❓
2. What is it’s tissue source❓
- Reversible interconversation of pyruvate to lactate
2. Cells of: Skeletal muscles Cardiac muscle Liver Kidney Brain Erythrocytes
LDH-1 is…
- Localized in what tissues❓
- Increased in what conditions❓
Heart
RBCs
Myocardial infarction
Hemolytic anemia
LDH-2 is…
- Localized in what tissues❓
- Increased in what conditions❓
Heart
RBCs
Megaloblastic anemia
Acute renal infarct
Hemolysed specimen
LDH-3 is…
- Localized in what tissues❓
- Increased in what conditions❓
Lung
Lymphocytes
Spleen
Pancreas
Pulmonary embolism Pneumonia Lymphocytosis Acute pancreatitis Carcinoma
LDH-4 is…
- Localized in what tissues❓
- Increased in what conditions❓
Liver
Hepatic injury
LDH-5 is…
- Localized in what tissues❓
- Increased in what conditions❓
Skeletal muscle
Skeletal muscle injury
- Amylase is an enzyme associated with❓
- What is it’s tissue source❓
- Molecular weight❓
- What is it’s diagnostic significance❓
- Breaks down starch and glycogen to maltose
- Acinar cells of pancreas
Salivary gland
MW: 50,000-55,000; filtered by glomerulus and seen in urine
- Acute pancreatitis
Severe glomerular impairment
Diabetic ketoacidosis
Perforated peptic ulcer
Macroamylasaemia Salivary calculi Acute cholecystitis Intestinal obstruction Abdominal trauma Mumps
Acid phosphatase is an enzyme
- Found in❓
- What is it’s diagnostic significance❓
1. Cells of: Prostate Liver Erythrocytes Platelets Bone
- Diagnosis and management of prostate cancer (has been replaced by PSA assay)
