For markers of acute myocardial infarction, common ones include creatine kinase, creatine kinase isoenzyme (CK-MB), and troponin T, troponin I, and myoglobin, of which troponin is more specific for diagnosing myocardial infarction and myoglobin is more sensitive. Cardiac enzymes and CK-MB generally start to rise 4-6 hours after myocardial infarction and reach a peak within 16-24 hours. It usually returns to normal in 3-4 days. Troponin begins to rise 3-4 hours after myocardial infarction, peaks at 4-6 hours, and can last 10-14 days. Myoglobin can generally begin to rise at 2-3 hours, but its specificity is poor.