Hospital
$120+
Other Labs
$40
TestWell
$30.99
Free T3 measures the unbound, active form of triiodothyronine, the most potent thyroid hormone. While T4 is produced in larger quantities, T3 is the hormone that actually drives metabolism at the cellular level. This test is especially useful for detecting T4-to-T3 conversion problems, which can cause hypothyroid symptoms even when TSH and T4 are normal.
Sample Type
Blood draw
Fasting
Not required
Results In
1–3 business days
Performed By
Labcorp
1 biomarker tested
Your Free T3 (Triiodothyronine) 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.
TestWell Price
$30.99
No insurance needed · HIPAA compliant
Frequently ordered together
Customers who ordered Free T3 (Triiodothyronine) 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
Free T3 (Triiodothyronine)
$30.99