Which biomarker indicates increased cardiac demand in suspected myocardial injury?

• A. Troponin
• B. Creatine kinase-MB
• C. Myoglobin
• D. Lactate

Answer: (A)

Troponin is the biomarker of choice when you suspect myocardial injury. Cardiac troponin I and T are proteins unique to heart muscle that are released into the blood when cardiomyocytes are damaged. This makes troponin highly specific for heart injury, unlike markers that can be released from skeletal muscle or other tissues.

After cardiac injury, troponin rises within a few hours, peaks around 24 hours, and remains elevated for several days. This time course allows clinicians to detect both early injury and ongoing damage, which is crucial for guiding treatment.

Other markers exist but are less ideal for confirming myocardial injury. CK-MB can come from skeletal muscle and is less specific, myoglobin rises early but isn’t specific to the heart, and lactate reflects overall tissue hypoperfusion rather than heart-specific injury. Because troponin provides the most reliable indication that heart muscle has been damaged, it best fits the scenario of increased cardiac demand leading to myocardial injury.