Which enzyme is commonly used as a marker for myocardial infarction?

• A. Alanine aminotransferase (ALT)
• B. Creatine kinase (CK)
• C. Lactate dehydrogenase (LDH)
• D. Amylase

Answer: (B)

Creatine kinase (CK) is widely recognized as a key marker for myocardial infarction (heart attack) due to its specific activity and presence in the cardiac muscle. When myocardial infarction occurs, the cardiac cells become damaged and release CK into the bloodstream, leading to elevated levels that can be measured in blood tests.

The measurement of CK, particularly the CK-MB isoenzyme, is particularly important because it is more specific to cardiac tissue compared to other forms of the enzyme found in different tissues. This allows clinicians to differentiate between cardiac-related issues and other conditions that may elevate total CK levels.

While other enzymes, such as alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and amylase, are relevant in various clinical conditions, they do not have the same specificity or sensitivity for myocardial infarction as CK does. For instance, ALT is primarily associated with liver function, LDH can be elevated in various tissue damage scenarios including liver and hemolysis, and amylase is primarily linked with pancreatic disorders. Thus, CK remains the enzyme of choice for assessing myocardial damage in clinical practice related to heart attacks.