Which biomarker is elevated in acute MI?

• A. D-dimer
• B. BNP
• C. Troponin
• D. CRP

Answer: (C)

Cardiac troponin elevation signals myocardial injury, which is the hallmark of an acute myocardial infarction. The troponin complex, specifically troponin I and troponin T, is highly specific to heart muscle, so when myocardial cells are damaged, these proteins spill into the bloodstream. This makes troponin the most reliable biomarker for diagnosing an MI. Levels begin to rise within a few hours after symptoms start, peak around 12–24 hours, and remain elevated for several days, which helps capture cases even if the presentation is delayed or serial testing is used.

D-dimer is a marker of clot breakdown and is not specific to heart muscle injury, so it isn’t diagnostic for an MI. BNP reflects ventricular wall stretch and is more useful for assessing heart failure and volume status. CRP is an inflammatory marker that can be elevated in many conditions, including MI, but it lacks the specificity needed to diagnose an acute MI on its own.