Which enzyme rises earliest following a myocardial infarction?

Which enzyme rises earliest following a myocardial infarction?

• A. CK
• B. AST
• C. LD
• D. ALT

Answer: (A)

When heart muscle is damaged, enzymes stored inside the cells spill into the bloodstream. Creatine kinase, especially the CK-MB isoenzyme that is more specific to heart tissue, leaks out very quickly. This makes it the earliest rising enzyme after a myocardial infarction, typically detectable within about 4–6 hours and peaking around the first day. AST and LD also rise with myocardial injury but they do so later than CK, while ALT is not a reliable indicator of heart injury. So CK is the earliest enzyme marker among these choices to rise after a myocardial infarction.

When heart muscle is damaged, enzymes stored inside the cells spill into the bloodstream. Creatine kinase, especially the CK-MB isoenzyme that is more specific to heart tissue, leaks out very quickly. This makes it the earliest rising enzyme after a myocardial infarction, typically detectable within about 4–6 hours and peaking around the first day. AST and LD also rise with myocardial injury but they do so later than CK, while ALT is not a reliable indicator of heart injury. So CK is the earliest enzyme marker among these choices to rise after a myocardial infarction.