TnI Alert Level:Greater than 1.4ng/mL
TnI Alert Level:Greater than 1.4ng/mL
The presence of a detectable amount of cardiac Troponin I (TnI) in serum or plasma indicates cardiac muscle injury, and its measurement can:
· detect acute myocardial infarction (AMI);
· detect AMI in the presence of significant skeletal muscle injury;
· stratify risk in patients with unstable angina;
· detect AMI in patients with chronic renal failure.
Reference ranges
· Normal - less than 0.4ng/mL.
· Evaluate further - greater than 0.4ng/mL.
· Alert level - greater than 1.4ng/mL.
Interpretation
Serial determinations from patients with AMI taken at six to eight hour intervals over the first 48 hours show rising patterns similar to those seen in creatine kinase-MB. First elevation is usually between four to eight hours following onset of chest pain. Peak elevation is usually at 12 to 16 hours with increased levels persisting for five to nine days following infarction.
Three serial determinations during 24 hours following chest pain are recommended. Any level greater than 1.4ng/mL may indicate AMI. Levels above 0.4ng/mL should be further investigated. Patients with unstable angina and elevated TnI may have an increased risk for subsequent coronary events. In cases where laboratory results fail to correlate with the clinical picture, additional investigation is necessary.
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