Hospital
$200+
Other Labs
$70
TestWell
$35.99
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.
Sample Type
Blood draw
Fasting
Not required
Results In
4–7 business days
Performed By
Labcorp
1 biomarker tested
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.
TestWell Price
$35.99
No insurance needed · HIPAA compliant
Frequently ordered together
Customers who ordered Reverse T3 also added these for a more complete health picture.
Measures total testosterone levels — the starting point for evaluating hormonal health in men and women.
$33.99
The definitive vitamin D test — an estimated 42% of American adults are deficient.
$41.99
General inflammation marker — elevated in infections, autoimmune conditions, and chronic disease.
$19.99
Reverse T3
$35.99