Troponin-T is preferable to CPK-MB in the diagnosis of acute myocardial infarction (MI) in all of the following situations except:

Answer is C (Reinfarction after four days) Because cardiac troponins are elevated for prolonged periods (> I week) an episode of recurrent ischaemia after four days would be more readily diagnosed with a marker that remains elevated in blood more briefly such as cKMB .4,41, returns to normal levels by 72 hours. Limitation of troponin measurements : Because these markers remain elevated for prolonged periods (> 1 week) episodes of recurrent ischemic discomfo and suspected recurrent MI are more readily diagnosed with a serum cardiac marker that remains elevated in the blood more briefly such as CKMB or myoglobin.