[Troponin, a new myocardial infarction marker].

The troponin (Tn) complex consists of three protein subunits referred to as TnT, TnI and TnC. Myocardium contains TnI and TnT isoforms which are not present in skeletal muscles and which can be separated from the muscular isoforms by immunological techniques. Using commercially available immunoassays, clinical laboratories are able to determine cardiac TnT and TnI (cTnT and cTnI) as quickly and reliably as classical cardiac markers. After acute myocardial infarction, cTnT and cTnI concentrations start to increase in serum in a rather similar way than CK-MB, but return to normal after longer periods of time (approximately one week). Because of their excellent cardiac specificity, Tn subunits appear ideally suited for the differential diagnosis of myocardial and muscular damage, for example in non cardiac surgery patients, in patients with muscular trauma or with chronic muscular diseases, or after intensive physical exercise. cTnT and cTnI may also be used for detecting evidence of minor myocardial damage, and therefore may find new applications in the management of patients with unstable angina.