Troponin I

Keywords: Cardiac enzymes

Specimen:

5 mL blood in lithium heparin tube.

Method:

Immunoassay.

Reference Interval:

Not detected for conventional assays and POCTs. Assay and population dependent for high sensitivity troponin assays (99th %).

Application:

Diagnosis of Myocardial infarction.

Interpretation:

The assays are specific for a cardiac isoform that occurs only in myocardium.

The test is very specific and sensitive for myocardial damage.

Reference intervals are method dependent, and are also gender dependent for the high sensitivity troponin I assays.

The current generation high sensitivity troponin assays become positive within 2-3 hours of onset of chest pain and remain raised for 7-10 days. The conventional assays and POC tests for troponin become abnormal within 12 hours of commencement of pain.

Diagnostic thresholds are very method dependent. Ensure the diagnostic thresholds and timing of troponin tests are appropriate for the troponin assay in use.

Elevations of troponin are specific for myocardial damage, but not necessarily Myocardial infarction, which requires clinical features and a rise and or fall in troponin for diagnosis.

Reference:

Lewandrowski K et al. J Clin Pathol 2002; 118: 93-99.

Thygesen K et al. Eur Heart J 2012; 33: 2551-2567.

Thygesen K et al. J Am Coll Cardiol 2012; 60: 1581-1598.

Apple FS et al. Clin Chem 2012; 58: 1574-1581.