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Test Code FRET4 T4, FREE

Important Note

The results of this assay can be falsely elevated due to the consumption of Biotin. Patients should discontinue the use of vitamins or supplements that contain Biotin 12 hours before blood draw. See Resources for more information.

Test subject to Medicare National Coverage Determination (NCD). See Medical Necessity documentation requirements by clicking on Medicare National Coverage Determinations under General Information to left of this screen.

Additional Codes

LAB127

Performing Laboratory

Porter Hospital Laboratory

Specimen Requirements

Specimen Type: Blood
Container/Tube: Tiger top, serum gel
Specimen Volume: Full tube, submit 0.5 mL serum
Specimen Minimum Volume: 0.2 mL 
Collection Instructions:
1. Send specimen in original tube.
2. If there is a delay in transport of >1 hour, centrifuge tube.
3. Centrifuged samples are stable for:

  • 7 days at 2 – 8ºC

Specimen Transport Temperature

Refrigerated

Test Classification and CPT Coding

84439

Test Schedule / Analytical Time / Test Priority / Turn Around Time

Daily / 24 Hours / Available STAT / Routine - 4 Hours

                                                       STAT - 60 Minutes

Normal Reference Values

0 up to 15 Days   1.0-4.1 ng/dL
15 Days up to 1 Months   0.8-2.3 ng/dL
1 Months up to 4 Months   0.8-1.8 ng/dL
4 Months up to 1 Years   0.8-1.7 ng/dL
1 Years up to 18 Years   0.8-1.4 ng/dL
18 Years up to Unspecified   0.8-2.2 ng/dL

Critical Values

None