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Free Thyroxine

Test Code

Free T4 (FT4)


Testing performed on Beckman Coulter Access2 Immunoassay Systems with serum testing.

Test Utility

Used in the aid of diagnosing thyroid function.

Specimen Storage and Stability

Store samples tightly stoppered at room temperature (15-30C) for no longer than eight hours. If the assay will not be completed within eight hours, refrigerate the samples at 2-8C. If the assay will not be complete within 48 hours, or for a shipment of samples, freeze at -20C or colder. Thaw samples only once.

Specimen Collection and Preparation

Serum sample recommended. Sample volumes need to be 4.0mL Gold Top or Tiger SST, free from hemolysis, whole blood cannot be used. Allow serum samples to clot completely before centrifuge, separate serum from red blood cells ASAP.

Specimen Rejection

  • Improperly labeled

  • Specimen grossly

  • Hemolyzed uncentrifuged

Reference Ranges

0.3 - 3.0 uIU/mL


Monday - Saturday, 16 hours a day.

Result available after getting the specimen in 5 hours.

STAT results available within 2 hours of receipt in the Laboratory.

*NOTE: All Specimen Refrigerated (2-8°C) for 7 days only.


Vibra Health Laboratory

Phone: (248) 846-0663

1307 Allen Dr, Suite A, Troy, MI 48083

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