Which biomarker is elevated in myocardial injury and used in diagnosis?

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

Answer: (A)

Troponin is the biomarker of choice for myocardial injury because its I and T isoforms are specific to cardiac muscle and are released into the bloodstream only when cardiomyocytes are damaged. This makes troponin highly sensitive and specific for myocardial infarction, enabling reliable diagnosis even when symptoms are subtle or when other markers might be confounded.

After injury, troponin levels rise within a few hours (about 3–4 hours) and peak around 24 hours, remaining elevated for several days (I a bit longer than T, often up to about a week or more). This prolonged rise allows detection of myocardial injury even if the patient presents later.

Other markers have limitations: CK-MB does rise with myocardial injury but is less specific because it can come from skeletal muscle injury as well, and it returns to baseline more quickly. Myoglobin rises very early but is not specific to the heart, so it’s not used alone for diagnosis. LDH is nonspecific and not helpful for acute diagnosis.