Troponin Interpretation

A troponin result is a signal, not a diagnosis. A value above the reporting laboratory's 99th-percentile upper reference limit (URL) establishes myocardial injury; it does not establish coronary thrombosis or myocardial infarction (MI). The next questions are whether the injury is acute, whether there is clinical evidence of myocardial ischaemia, and what mechanism best explains the pattern. For Canadian NP practice, begin with the patient's symptoms, onset and trajectory, a 12-lead ECG, haemodynamic status and the assay used by the local laboratory. High-sensitivity cardiac troponin (hs-cTn) is usually reported as a whole number in ng/L, but the URL and the permitted change between samples vary by platform. A result cannot be interpreted safely by importing a cut-off from another hospital or website. The practical sequence is simple: identify injury, establish its time course, connect it—or do not connect it—to ischaemia, and then treat the cause. This prevents two dangerous errors: labelling every elevated troponin as type 1 MI, and dismissing an early or rising result because the initial value is low. A diagnostic ECG showing STEMI changes takes priority over...