Complete Thyroid Panel

Five tests: TSH (screening), Free T4 (active circulating thyroxine), Free T3 (the most metabolically potent form), Reverse T3 (inactive 'brake' form), and TPO Antibodies (autoimmune marker). Together they distinguish primary vs central hypothyroidism, T3 toxicosis, autoimmune cause, and impaired peripheral conversion.

TSH alone catches most primary thyroid disease, but misses central (pituitary) cause, T3 toxicosis, conversion problems, and silent autoimmune thyroiditis. Thyroid Complete catches all of those. If you have classic thyroid symptoms with a 'normal' TSH, this panel is the right next step.

Reverse T3 is the inactive form your body produces under stress, illness, or caloric restriction. Elevated rT3 with normal TSH and Free T4 can indicate stress-induced 'cellular hypothyroidism' or impaired T4-to-T3 conversion — explaining symptoms that the standard tests miss. Mainstream endocrinology is skeptical; functional medicine relies on it heavily.

Positive TPO Antibodies suggest autoimmune thyroid disease (Hashimoto's), the most common cause of hypothyroidism in the US. They can be elevated for years before TSH abnormalities appear — useful for risk-stratifying and timing repeat TSH monitoring.

On TestWell, the Complete Thyroid Panel is $109.99. Ordering the same 5 tests separately would be about $135. Quest Direct lists comparable bundles at $195, walk-in hospital labs typically bill $400-600 for the same biomarkers without insurance.

No fasting required for thyroid tests. Draw at the same time of day for serial monitoring (TSH has a mild circadian rhythm), and at least 4 hours after your levothyroxine dose if on thyroid replacement therapy.

Optional — about 5% of Hashimoto's patients are TPO-negative but Thyroglobulin-positive. The standalone Thyroid Antibodies bundle includes both. If you've already tested TPO-positive, adding Thyroglobulin Ab rarely changes management.

Annually if you have known thyroid disease that's well-managed. Every 6-8 weeks when starting or adjusting levothyroxine. Every 3 months in pregnancy or postpartum. Once for baseline if you're TPO-positive but euthyroid.

Complete Thyroid Panel results are typically ready in 3–7 business days after your draw at Quest or Labcorp. TestWell emails you the moment they post, and your results dashboard shows each marker against its reference range with a plain-English explanation.

Biotin supplements, levothyroxine timing and ashwagandha and thyroid-support supplements can change a Complete Thyroid Panel result without anything being wrong. Biotin supplements can falsely lower TSH and can falsely raise Free T4 — stop biotin ≥72 hours before the draw. Levothyroxine timing can raise Free T4 and Free T3 — draw before the daily dose, then take it. Ashwagandha and thyroid-support supplements can lower TSH and can raise Free T4 — note the supplement on a thyroid panel; a clinician may repeat TSH after a planned pause. Each factor is covered on our physician-reviewed "Before your test" pages; when one applies, the fix is usually to remove it and retest.

Order the Complete Thyroid Panel online from TestWell for $109.99 (plus a $6 per-order lab processing fee) — no doctor's visit, referral or insurance needed. A licensed physician authorizes the order, then you walk into any Quest or Labcorp patient service center near you for the draw (the lab locator on our site lists the closest ones by ZIP code), and results arrive in 3–7 business days.