Troponin is a complex composed of 3 proteins (troponin C, troponin I, troponin T) mediating interaction between myosin and actin. A cardiac specific form of troponin I is present which is released into the serum when myocyte injury occurs.


Reference range in serum: <= 3.1 µg/L


Time course: biphasic with early peak and secondary peak at 60-80 hours after infarction



Timing After AMI

earliest increase

4 - 6 hours

peak level

10 - 24 hours

return to normal

10 - 15 days



• The duration of elevation may limit use in the diagnosis of myocardial injury occurring after heart surgery when preoperative cardiac injury was present.



• sensitivity: > 98%

• specificity: 95%

• Serial monitoring more useful than single determinations.

• Duration of elevation after injury overlaps with that of lactate dehydrogenase, and can be used to diagnose myocardial infarction having a late presentation for medical care (retrospective diagnosis).

• Rhabdomyolysis usually does not cause increases in troponin I.

• Acute or chronic skeletal muscle injury does not cause increases in troponin I, so that it can be useful when CK-MB is obscured by skeletal muscle injury.

• It is not elevated in renal failure patients.

• ROC curve analysis shows diagnostic accuracy indistinguishable from CK-MB for diagnosis of acute myocardial infarction.


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