Questions and Answers
What is the primary characteristic of functional plasma enzymes?
What is the primary factor in selecting an enzyme to test for a disease?
Which of the following enzymes is an example of a non-functional plasma enzyme?
What is the liver: blood ratio of an enzyme that should make it a readily detectable elevation in blood levels?
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What is the significance of measuring changes in the activities of non-functional plasma enzymes in disease?
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Which of the following enzymes is rapidly inactivated on entering the vascular compartment after a myocardial infarction?
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Why is a particular enzyme not used in clinical enzymology despite its potential?
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What is the characteristic of ornithine carbamyltransferase?
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Which of the following enzymes is primarily sourced from the prostate and RBCs?
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What is a key factor in selecting enzymes for clinical enzymology?
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What is the significance of non-functional plasma enzymes in clinical chemistry?
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Which enzyme is commonly used in the diagnosis of pancreatic diseases?
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Which of the following enzymes is synthesized by the liver, skeletal muscle, heart, and brain?
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Which of the following enzymes is specific to the liver?
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What is the primary application of Aspartate aminotransferase (AST)?
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What is the main factor affecting enzyme activity?
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What is the criteria for selecting enzymes for testing in clinical enzymology?
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What is the main reason why enzyme activity is easier to measure than protein concentration?
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What is the definition of clinical enzymology?
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What is the primary purpose of measuring enzyme activity in plasma?
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Which of the following enzymes is used in the diagnosis of organophosphorus insecticide poisoning?
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What is the term for multiple forms of an enzyme that catalyze the same reaction?
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Study Notes
Plasma Enzymes
- Plasma enzymes can be classified into two types: functional and non-functional plasma enzymes
- Functional plasma enzymes are present in plasma at higher concentrations than in tissues and function in plasma
- They are mostly synthesized by the liver and usually decrease in disease conditions
- Examples of functional plasma enzymes include clotting enzymes and lipoprotein lipase
Non-Functional Plasma Enzymes
- Non-functional plasma enzymes are present in tissues at higher concentrations than in plasma and do not have any function in plasma
- They are mostly synthesized by the liver, skeletal muscle, heart, and brain
- They usually increase in disease conditions
- Examples of non-functional plasma enzymes include creatine kinase and alanine transaminase
- Measurement of these enzymes in plasma can be used to assess cell damage and proliferation, i.e., diagnosis of disease
Criteria for Selection of Enzyme Tests
- The selection of enzyme tests depends on the distribution of enzymes among various tissues
- Not all intracellular enzymes are equally valuable as indicators of cellular damage
- Other factors, such as rate of disappearance from blood, ease of assay, cost of assay, and quantity in blood, also define the enzymes of clinical interest
Distribution of Diagnostically Important Enzymes
- Acid phosphatase: prostate, RBCs; principal clinical application: carcinoma of prostate
- Alanine aminotransferase (ALT): liver, skeletal muscle, heart; principal clinical application: hepatic parenchymal disease
- Aldolase: skeletal muscle, heart; principal clinical application: muscle diseases
- Amylase: salivary glands, pancreas, ovaries; principal clinical application: pancreatic diseases
- Aspartate aminotransferase (AST): liver, skeletal muscle, heart, kidney, RBCs; principal clinical application: myocardial infarction, hepatic parenchymal disease, muscle disease
- Cholinesterase: liver; principal clinical application: organophosphorus insecticide poisoning, hepatic parenchymal diseases
- Creatine kinase (CK): skeletal muscle, brain, heart, smooth muscle; principal clinical application: myocardial infarction, muscle diseases
- g-Glutmyltransferase (GGT): liver, kidney; principal clinical application: hepatobiliary disease, alcoholism
- Lactate dehydrogenase (LDH): heart, liver, skeletal muscle, RBCs, platelets, lymph nodes; principal clinical application: myocardial infarction, haemolysis, hepatic parenchymal diseases
Clinical Enzymology
- Clinical enzymology is the measurement of some selected enzymes in specimens (usually of blood, especially plasma) for detection and monitoring of diseases
- Changes in plasma enzyme activities help to detect and localize tissue cell damage or proliferation, or to monitor treatment and progress of disease
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Description
Learn about the classification of plasma enzymes into functional and non-functional types, their characteristics, and examples of each.