Figure 50-6 Time course of elevations in serum markers after acute myocardial infarction (AMI). This figure summarizes the relative timing, rate of rise, peak values, and duration of elevation above the upper limit of normal for multiple serum markers after AMI. Although total creatine kinase (CK), CK-MB, and lactate dehydrogenase (LDH [with isoenzymes]) are traditionally measured, the relatively slow rate of rise above normal for CK and the potential confusion with noncardiac sources of enzyme release for both total CK and LDH have inspired the search for additional serum markers. The smaller molecule myoglobin is released quickly from infarcted myocardium but is not cardiac specific. Therefore, elevations in myoglobin that may be detected quite early after the onset of infarction require confirmation with a more cardiac-specific marker such as CK-MB or troponin I. Troponin I (and troponin T, not shown) rises more slowly than myoglobin does and may be useful for diagnosis of infarction even up to 3 to 4 days after the event. Monoclonal antibody assays for cardiac-specific troponin I and troponin T are now available. (From Antman EM: General hospital management. In Julian DG, Braunwald E [eds]: Management of Acute Myocardial Infarction. London, WB Saunders, 1994.)