Marker of myocardial injury. Troponin I is one of three proteins of the troponin complex that regulates the calcium mediated interaction of actin and myosin. Troponin I demonstrates slightly better cardiac specificity than does CK-MB. Serum levels of troponin I begin to rise 4 to 6 hours after an acute myocardial infarction, with peak concentrations being reached in approximately 12-18 hours after infarction. Unlike other cardiac markers (CKMB, Myoglobin), Troponin I levels remain elevated in plasma for several days before returning to normal. Troponin I may be elevated in a number of cardiac conditions other than AMI, including unstable angina.
< 0.30 ng/mL
- TROPONIN LEVEL
STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).
Collect specimen in a green top tube. Centrifuge, aliquot plasma into a plastic vial and refrigerate.
Because of its greater specificity, the laboratory promotes the use of Troponin I as the primary marker for myocardial damage. Because Troponin I can remain elevated for many days after an infarction, the markers with much shorter time courses of disappearance such as CK-MB and myoglobin can be used to help ascertain the timing of the initial damage or detect reinfarction.