Troponin I

Tube Type

Test ID   LAB747
EPIC Order
CPT Code(s)   84484
Group/Individual Test   Individual 
Laboratory   Core Laboratory
Tube Station   Routine: 30; STAT: 888
Specimen Routine: 4 mL blood/serum separator/gold toptube/red top acceptable; see Comments
  Micro: 1 mL blood/serum separator/gold top tube/red top 
Unspun: 8 hours
Spun/Separated, Room Temp-</=8 hrs recommended
Spun/Separated, Refrigerator: 7 days
Spun/Separated, Frozen: 4 weeks
Availability Routine: 24 hrs/day
  STAT: Yes
Turnaround Time   Routine: 2 hrs; STAT: 1 hr
Reference Range Normal: <0.034 ng/mL
  Critical: >0.034 ng/mL for initial result

The Troponin I (TnI, Ortho Clinical Diagnostics) assay is specific to myocardium and does NOT cross react with the skeletal muscle Troponin I isotypes.

Heterophilic antibodies may cause interference.  High doses of biotin may cause test interference.

Reference range: <0.034 ng/mL. The 99th  percentile upper reference limit is 0.034 ng/mL.

Hemolysis increases Troponin I values due to an analytical interference (TnI is not in erythrocytes).    

Detectable levels of Troponin I are seen within 4-6 hours following an acute myocardial infarction (AMI) and remain elevated for 7-14 days. Because Troponin I reflects myocardial cell damage, conditions other than AMI will result in increases in TnI concentrations. Such include sepsis, congestive heart failure, hypertension with left ventricular hypertrophy, hemodynamic compromise, myocarditis, mechanical injury including surgery, defibrillation, and cardiac toxins. This means TnI will be detected in patients who have had myocardial injury but not necessarily an AMI. For AMI, one should look for increasing concentrations across serial samples.   For those patients with low or stable levels, remember that TnI has long been shown to be a good risk assessment marker for evaluating patients with unstable angina and acute coronary syndrome. 

Conversion formulae cannot be used to convert TnT to TnI or TnI to TnT because of the unique release characteristics and metabolism of each. TnT does not equal TnI.   

Reviewed by Christopher Parker on December 16, 2019

Note: Reference ranges provided on this web site are for guidance only, and may not reflect the most recent changes. Refer to laboratory reports for current reference data.

UNC Hospitals
McLendon Clinical Laboratories
101 Manning Drive
Chapel Hill, NC 27514