Troponin I and Troponin T

Troponin is a regulatory protein found in striated muscle (myocardial and skeletal). Increased amounts of troponin are released into the bloodstream when an infarction causes damage to the myocardium. Troponin levels are elevated as early as 3 hours after MI. Troponin I levels may remain elevated for 7 to 10 days and Troponin T levels may remain elevated for as long as 10 to 14 days. Serial measurements are important to compare with a baseline test; elevations are clinically significant in the diagnosis of cardiac pathology.

Normal Lab Value for Troponin

• Troponin: Less than 0.04 ng/mL; above 0.40 ng/mL may indicate MI
• Troponin T: Greater than 0.1 to 0.2 ng/mL may indicate MI
• Troponin I: Less than 0.6 ng/mL; >1.5 ng/mL indicates myocardial infarction

Nursing Considerations

• Rotate venipuncture sites.
• Testing is repeated in 12 hours or as prescribed, followed by daily testing for 3 to 5 days.