The short answer
Measures inactive T3 — helps identify thyroid hormone conversion issues and chronic stress effects, measured from a standard blood draw. At TestWell it costs $35.99 plus a $6 lab fee, needs no fasting, and results post in 4–7 business days. Physician-authorized with no doctor's visit or insurance needed; draw at Quest or Labcorp.
Hospital Lab
$200
cash pay
Other Labs
$70
+ lab fees
TestWell
$35.99
+ $6 lab fee
Reverse T3 (rT3) is an inactive form of T3 that is produced when the body converts T4 to rT3 instead of active T3. This can happen during periods of stress, illness, caloric restriction, or inflammation. High rT3 can cause hypothyroid-like symptoms even when TSH and T4 appear normal. It's particularly useful for evaluating complex thyroid cases.
Measures the inactive 'mirror' form of T3 the body produces under stress, illness, or caloric restriction. High Reverse T3 with normal TSH can indicate cellular hypothyroidism.
Anyone with persistent fatigue, weight gain, and cold intolerance despite normal TSH and Free T4; patients with chronic illness, eating disorders, or stress-related thyroid concerns.
Sample Type
Blood draw
Fasting
Not required
Results In
4–7 business days
Performed At
Quest or Labcorp
Your Reverse T3 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 4–7 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.
A Reverse T3 test costs $35.99 at TestWell — $41.99 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 $200.00 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) | $35.99 | $41.99 | Includes the one $6 lab processing fee, charged once per order |
| Hospital outpatient lab, self-pay (typical) | $200.00 | $200.00 | Reference figure; hospital charges vary widely by facility and are often higher |
Lab test codes: Quest test code 90963 · Labcorp test no. 070104 · BioReference code T397-9. 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
$35.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Better value: the Complete Thyroid Panel
Save $10.97This test is part of the Complete Thyroid Panel — 4 tests · 5 biomarkers for $109.99, $10.97 less than à la carte.
$109.99$120.96
4 tests · 5 biomarkers
Frequently ordered together
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Reverse T3
$35.99