Reference range in serum: <= 3.1 µg/L
Time course: biphasic with early peak and secondary peak at 60-80 hours after infarction
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Course
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Timing After AMI
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earliest increase
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4 - 6 hours
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peak level
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10 - 24 hours
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return to normal
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10 - 15 days
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Limitations:
• The duration of elevation may limit use in the diagnosis of myocardial injury occurring after heart surgery when preoperative cardiac injury was present.
Performance:
• 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.
