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Test Code Billings Clinic: 0226 Troponin - High Sensitivity, Plasma or Serum

Important Note

The use of a single sample type (either lithium-heparin plasma or serum) is recommended for troponin analysis when collecting serial samples from the same patient.

 

If the cTnI result is below the 99th percentile value at the first blood draw, at least two additional blood samples should be drawn before results are interpreted as negative for AMI.

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

The temporal elevation of cardiac troponin I concentration is a useful tool in the diagnosis of acute myocardial infarction (AMI).

Methodology

Sandwich Immunoassay / Direct Chemiluminescence

 

Specimen Requirements

Submit only 1 of the following specimens:

Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of 1 hour from the time of collection.

 

Plasma

  • Draw blood in a green-top (lithium heparin) tube(s).
  • Spin down and send 1.0 mL of heparinized plasma frozen.

 

Serum

  • Draw blood in a serum gel tube(s).
  • Spin down and send 1.0 mL of serum frozen

Storage/Stability

Specimen Type Temperature Time
Plasma, Serum Refrigerated 24 hours
  Frozen(preferred) 40 days
  Ambient 8 hours

 

Reject Due To

  • Specimens containing fibrin, red blood cells or suspended particles
  • Samples stored in a frost-free freezer
  • Specimens frozen and thawed more than once
  • Specimens received outside of the stated storage requirements

Reference Values

Females

< 34 ng/L

 

Males

< 54 ng/L

 

Critical Value:

> 98 ng/L
 

Sequential measurements on specimens drawn at intervals over a 48-hour period post-AMI will result in the classic rise in concentration seen with other markers of AMI such as creatine kinase (CK)-MB. Troponin I will remain elevated for 5 to 9 days.

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

84484 - Troponin, quantitative

LOINC Code Information

Reporting Name LOINC Code
Troponin - I, hs 49563-0