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Calculate my fitLabbrary's review, Fit Score, and basic comparison are free. The provider's panel, shipping, collection, clinician review, and other services are separate. About 2 minutes. No account required.
Measures unbound thyroxine to help interpret thyroid function alongside TSH, follow up an abnormal result or monitor treatment. Order this single-marker test online for a participating laboratory blood draw.
- Current price
- $5.52 from $15.02 with fees
- Sample
- Blood
- Turnaround
- 1 to 2 days
- Access
- Lab Visit, Order Online
Evidence & Key Facts
Evidence basis. This named result reflects the sources and verification evidence listed on this page as of the date shown.
Thyroid
One directly measured free T4 result.
This is free T4, not the calculated free thyroxine index. Medication timing and certain medicines can affect interpretation; follow the selected laboratory and clinician instructions.