troponin

[bruny]

Three days from now i'm starting a new job in CCU after being off work injured for 3 years *eek* - can anyone tell me quickly about troponin, is it a cardiac specific enzyme, when do its levels peak, is it in use more than CKMB now?

[Doey, BSN, RN]

CKMB is still used along with Troponin I. They both rise about 5-7hrs after MI but the troponin remains elevated much longer, 8 days or so. Troponin is cardiac specific. There have been studies done in pts. who received cardioversion, defibrillation or falls who presented with elevated CKs but troponin remained negative. Also troponin is being looked at as a possible predictor of prognosis or of future cardiac events. Some pts. presenting with unstable angina with negative CKMB and EKG findings and a slightly eleveated troponin have been found on echocardiographic testing to have some wall motion abnormalities indicating myocardial damage. There have been instances of false positive troponins but improvement in lab techniques have decreased this. There is also the thinking that perhaps these so called false positive results are really indicative of subclinical myocardial damage. Troponin is also useful in determining if infarction has occurred prior to hospitalization in pts. who have experienced atypical or non-specific symptoms and then days later present to the ED with c/p etc. and have CKMB within the normal range but elevated troponin, probably indicating they infarcted at the time of their original symptoms.