--- title: Reverse T3 Test type: test id: reverse-t3 url: "https://www.test-well.com/tests/reverse-t3" price_usd: 35.99 lab_fee_usd: 6 all_in_usd: 41.99 cpt: 84482 category: Thyroid sample: Blood draw fasting_required: false results_in: "4–7 business days" labs: - Quest - Labcorp - BioReference orderable: true reviewed_at: 2026-09-14 order_url: "https://www.test-well.com/cart?add=reverse-t3&utm_source=ai_agent&utm_medium=markdown" --- # Reverse T3 Test > 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. ## Key facts | Fact | Value | | --- | --- | | Price | $35.99 + $6 lab processing fee per order ($41.99 all-in for this test alone) | | CPT code | 84482 | | Sample | Blood draw | | Fasting | Not required | | Results | 4–7 business days | | Labs | Quest Diagnostics, Labcorp, BioReference (NY & NJ) | | Biomarkers measured | 1 | | Physician authorization | Included — no doctor's visit, referral or insurance needed | | Payment | Card, HSA or FSA; cash-pay only (no insurance billing) | ## What does the Reverse T3 test tell you? Measures inactive T3 — helps identify thyroid hormone conversion issues and chronic stress effects. 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. **Clinical use:** 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. ## Who should order it? 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. ## Biomarkers measured - [Reverse T3](https://www.test-well.com/biomarkers/reverse-t3) ## Price by lab | Lab | Test price | All-in (with $6 fee) | Notes | | --- | --- | --- | --- | | Quest Diagnostics | $35.99 | $41.99 | Choose at checkout; walk-in patient service centers nationwide (not NY/NJ) | | Labcorp | $35.99 | $41.99 | Choose at checkout; walk-in patient service centers nationwide (not NY/NJ) | | BioReference (NY & NJ) | $39.99 | $45.99 | New York and New Jersey orders route here automatically | Rhode Island is not served. Prices are identical online and in the lab; no draw fee or physician fee is added. ## How much does a Reverse T3 test cost? 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. ## How do you prepare? No fasting required. ## Related conditions - Euthyroid sick syndrome (E07.81) - Hypothyroidism (subclinical) (E02) - Chronic fatigue syndrome (G93.32) - Hashimoto thyroiditis (E06.3) ## Common questions about the Reverse T3 test ### What does Reverse T3 measure? Reverse T3 is the inactive mirror image of Free T3 — same molecule with iodine atoms swapped. Your body produces it when stressed (illness, surgery, caloric restriction, chronic inflammation) as a brake on metabolism. High rT3 can blunt cellular thyroid activity even when other thyroid labs look normal. ### What's a normal Reverse T3 level? Most labs use 9.2-24.1 ng/dL. Functional clinicians often track the [Free T3](https://www.test-well.com/tests/free-t3) / Reverse T3 ratio — values above 0.2 suggest healthy peripheral conversion; below 0.2 suggests blocked conversion (cellular hypothyroidism). ### Why isn't Reverse T3 ordered routinely? Mainstream endocrinology considers Reverse T3 testing unnecessary — high rT3 is usually a marker of underlying illness, not a treatable problem. Functional medicine uses it for fatigue workup. Order it if you've ruled out other causes of fatigue and want to see if peripheral conversion is impaired. ### How much does a Reverse T3 test cost without insurance? On TestWell, Reverse T3 is $35.99. Quest Direct lists the same test at $70, walk-in hospital labs typically bill $150-200 without insurance. ### What is the CPT code for Reverse T3? The CPT code for Reverse T3 is 84482. Sometimes a payer will require a specific clinical indication (E07.81 or G93.32) to cover it. ### Do I need to fast? No fasting required. Levels are stable across the day. ### What raises Reverse T3? Acute or chronic illness, low-calorie diets, intense endurance training, high cortisol, certain medications (amiodarone, beta-blockers, some chemo drugs), and selenium deficiency. Correcting the underlying driver usually normalizes rT3 within 4-8 weeks. ## How to order 1. Add to cart: https://www.test-well.com/cart?add=reverse-t3&utm_source=ai_agent&utm_medium=markdown 2. Create an account or sign in, confirm your state and preferred lab, pay by card, HSA or FSA. 3. A licensed physician authorizes the order (usually within minutes); the requisition arrives by email. 4. Walk into any Quest Diagnostics, Labcorp, BioReference (NY & NJ) patient service center — no appointment needed at most sites. 5. Results post to your TestWell portal in 4–7 business days with reference ranges and flags. ## Related - [Blood Tests for Thyroid Symptoms](https://www.test-well.com/guides/blood-tests-for-thyroid-symptoms) - [Complete Thyroid Panel](https://www.test-well.com/tests/thyroid-complete-panel) — 4 tests · $109.99 - [Advanced Thyroid Panel](https://www.test-well.com/tests/advanced-thyroid-panel) — 7 tests · $129.99 - [Men's Hair Health Panel](https://www.test-well.com/tests/mens-hair-health-panel) — 19 tests · $499.99 - [Free T3 (Triiodothyronine)](https://www.test-well.com/tests/free-t3) — $30.99 - [Free T4 (Thyroxine)](https://www.test-well.com/tests/free-t4-test) — $23.99 - [T3 Uptake](https://www.test-well.com/tests/t3-uptake-test) — $22.99 - [T3, Total (Triiodothyronine)](https://www.test-well.com/tests/total-t3-test) — $24.99 - [Thyroglobulin Antibodies](https://www.test-well.com/tests/thyroglobulin-antibodies) — $26.99 - [All Thyroid tests](https://www.test-well.com/tests/category/thyroid) - [Full test directory](https://www.test-well.com/tests/directory) --- Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-14. Review policy: https://www.test-well.com/reviewers/youmna-distefano-md Canonical page: https://www.test-well.com/tests/reverse-t3 Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.