The short answer
Measures free (unbound) T4 — the primary hormone produced by the thyroid gland, measured from a standard blood draw. At TestWell it costs $23.99 plus a $6 lab fee, needs no fasting, and results post in 1–3 business days. Physician-authorized with no doctor's visit or insurance needed; draw at Quest or Labcorp.
Hospital Lab
$150
cash pay
Other Labs
$40
+ lab fees
TestWell
$23.99
+ $6 lab fee
Free T4 (thyroxine) is the unbound, biologically active form of the primary thyroid hormone. It is converted to T3 (the more active form) in tissues throughout the body. Free T4 is the most reliable marker of actual thyroid hormone production because it is not affected by changes in binding proteins. Elevated Free T4 suggests hyperthyroidism, while low levels indicate hypothyroidism. This test is most useful when ordered alongside TSH for a complete picture of thyroid function, but can also be ordered standalone to monitor patients on thyroid medication.
Measures the unbound (active) form of thyroxine. Pairs with TSH to confirm thyroid dysfunction and distinguish primary from central causes.
Anyone with abnormal TSH, fatigue, weight changes, hair thinning, cold intolerance, or other symptoms of thyroid disease. Monitoring patients on levothyroxine or methimazole therapy.
Sample Type
Blood draw
Fasting
Not required
Results In
1–3 business days
Performed At
Quest or Labcorp
Your Free T4 (Thyroxine) results will include values for each of the 1 biomarker tested, along with reference ranges. Results are reviewed by a licensed physician before being released to your secure portal.
If any values fall outside the normal range, your report will include guidance on what that may mean and recommended next steps. You'll receive an email notification when your results are ready, typically within 1–3 business days.
Typical reference range layout
Lab reports show where your value sits relative to established reference intervals—your physician interprets this in context for you.
No fasting required. If on thyroid medication, take your dose after the blood draw.
A Free T4 (Thyroxine) test costs $23.99 at TestWell — $29.99 all-in when ordered alone, because the $6 lab processing fee is charged once per order, with no draw fee or physician fee added. Hospital outpatient labs typically bill around $150.00 self-pay for the same test, and often more. With insurance, what you pay depends on your deductible and your plan's negotiated rate; TestWell's price is fixed before the draw and is HSA/FSA-eligible.
| Where you order | Price | One test, all-in | Notes |
|---|---|---|---|
| TestWell (drawn at Quest or Labcorp) | $23.99 | $29.99 | Includes the one $6 lab processing fee, charged once per order |
| Hospital outpatient lab, self-pay (typical) | $150.00 | $150.00 | Reference figure; hospital charges vary widely by facility and are often higher |
Lab test codes: Quest test code 866 · Labcorp test no. 001974 · BioReference code 0091-9. Competitor prices are read from the linked public pages and re-checked regularly; the labs' sites may add taxes or change prices without notice.
TestWell Price
$23.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Frequently ordered together
Customers who ordered Free T4 (Thyroxine) also added these for a more complete health picture.
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Free T4 (Thyroxine)
$23.99