Lab Test

Free T4 (Thyroxine) by Equilibrium Dialysis

This test is subject to pathology approval prior to sending to the reference laboratory for testing. , ARUP #93244, Order as a Miscellaneous Sendout.


This test is only available to Endocrinologists and Nuclear Medicine Physicians.

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: one Red top tube.

Physician Office/Drawsite Specimen Preparation

Centrifuge to separate serum from cells. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 2.0 mL serum, refrigerated (2-8°C or 36-46°F). (Min: 0.3 mL)

Rejection Criteria

  • Specimens not collected and processed as indicated.


Sunday, Tuesday, Thursday.
Results available in 2-7 days.

Reference Range

By Report.

Test Methodology

High Performance Liquid Chromatography-Tandem Mass Spectrometry.


By Report.

CPT Code


Test Codes

ARUP #93244, Order as a Miscellaneous Sendout.

Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.