Which biomarker is most specific for myocardial injury?

• A. CK-MB
• B. Troponin
• C. Myoglobin
• D. BNP

Answer: (B)

Troponin is the most specific biomarker for myocardial injury because the cardiac troponins I and T are unique to heart muscle and are released into the blood only when cardiac myocytes are damaged. This cardiac specificity makes troponin elevations a reliable indicator of myocardial injury, such as in a myocardial infarction, and it remains elevated for a longer period, aiding diagnosis.

In contrast, myoglobin rises quickly after injury but is found in both cardiac and skeletal muscle, so it’s very sensitive but not specific. CK-MB is more cardial-specific than total CK but can be elevated with skeletal muscle injury or other situations, reducing its specificity. BNP reflects myocardial wall stress and heart failure rather than acute injury, so it’s not the best marker for diagnosing myocardial injury itself.