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Troponin I

Mnemonic:    [TROPONIN]
Name:    Troponin I
Specimen:    1 mL plasma from a Green PST. Drawn at timed intervals. See special timing instructions for Myocardial Profile.
Minimum Spec:    0.5 mL
Spec Stability:    Stable 7 days refrigerated.
Reference Range:    < or = 0.03 ng/mL is considered normal
  Method:    Chemiluminescent Immunoassay
Note:    Note: Updated assay, interpretive information and reference ranges as of February 7, 2008.


Upper Reference Limit (URL).........less than or equal to 0.03 ng/mL

Myocardial injury is reflected by an increased troponin level above the 99th percentile of a normal reference population. Myocardial injury cannot be reliably ruled out until at least two successive samples, obtained over no less than 6 hours yield completely negative results.

Myocardial infarction is diagnosed when myocardial injury exists in the clinical setting of acute myocardial ischemia.

Increased troponin concentrations may be found in conditions other than AMI that can result in myocardial damage. These conditions include, but are not limited to: sepsis, congestive heart failure, hypertension with left ventricular hypertrophy, hemodynamic compromise, myocarditis, mechanical injury including cardiac surgery, defibrillation, chronic renal failure and cardiac toxins.

In the setting of a percutaneous coronary intervention (PCI), a PCI-related myocardial infarction may be considered when there is a troponin increase of greater than 3 x 99th percentile URL (0.10 ng/mL) in addition to clinical evidence of ischemia.

In the setting of coronary artery bypass grafting (CABG), a CABG-related myocardial infarct may be considered when there is a troponin increase of greater than 5 x 99th percentile URL (0.17 ng/mL) plus either new pathologic Q waves or new LBBB, or angiographically documented new graft or native coronary artery occlusion, or imaging evidence of new loss of viable myocardium.

Universal definition of myocardial infarction; Thygesen, K et al, European Heart Journal (2007) 28, 2525-2538.
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