Which serum markers are commonly elevated in an acute MI?

Which serum markers are commonly elevated in an acute MI?

• A. CK-NB
• B. CK-MB and Troponin I
• C. Myoglobin only
• D. ALT and AST

Answer: (B)

When heart muscle is damaged in an acute MI, certain proteins spill into the blood, and their pattern helps confirm the diagnosis. Troponin I is highly specific to cardiac muscle, so its presence in the blood is a strong indicator of myocardial injury, and it stays elevated for days, making it reliable for diagnosing MI even if the patient presents later. CK-MB, the cardiac isoenzyme of creatine kinase, rises earlier after infarction—within hours—and peaks around a day before returning to baseline in a couple of days. Using both markers together gives both early detection and cardiac-specific confirmation. Myoglobin can rise very early, but it isn’t specific to the heart since it’s found in skeletal muscle too, so it’s less useful alone for diagnosing MI. ALT and AST are enzymes more indicative of liver (or broader muscle) injury and aren’t used to diagnose MI.

When heart muscle is damaged in an acute MI, certain proteins spill into the blood, and their pattern helps confirm the diagnosis. Troponin I is highly specific to cardiac muscle, so its presence in the blood is a strong indicator of myocardial injury, and it stays elevated for days, making it reliable for diagnosing MI even if the patient presents later. CK-MB, the cardiac isoenzyme of creatine kinase, rises earlier after infarction—within hours—and peaks around a day before returning to baseline in a couple of days. Using both markers together gives both early detection and cardiac-specific confirmation.

Myoglobin can rise very early, but it isn’t specific to the heart since it’s found in skeletal muscle too, so it’s less useful alone for diagnosing MI. ALT and AST are enzymes more indicative of liver (or broader muscle) injury and aren’t used to diagnose MI.