Also known as: TSH with Reflex to Free T4
The short answer
TSH with Reflex to Free T4 measures TSH and Free T4 (reflex) from a standard blood draw. At TestWell it costs $29.99 plus a $6 lab processing fee, needs no fasting, and results post in 1–3 business days. Physician-authorized with no doctor's visit or insurance needed; draw at Quest or Labcorp.
TestWell Price
$29.99
+ $6 lab processing fee
TSH is the most sensitive single test for thyroid function, but on its own it cannot say how severe an abnormal result is. Free T4 does that — it separates an underactive thyroid (high TSH, low free T4) from the milder subclinical pattern (high TSH, normal free T4), and an overactive thyroid from subclinical hyperthyroidism — but ordering it for everyone adds a test most people do not need. A reflex order solves this: the laboratory runs TSH, and only when the value falls outside its reference range does it run free T4 on the same sample, automatically, with no second visit. This is the screening order most primary-care clinicians write and what the labs call "TSH with reflex to free T4" (Quest 36127, Labcorp 349829). It suits a first thyroid check, routine monitoring where TSH has always been normal, and symptom work-ups where a normal TSH would end the question. If your TSH has been abnormal before, if you take levothyroxine, or if you want the fuller picture regardless, order TSH + Free T4 together or a thyroid panel instead.
Thyroid testing measures the hormones that regulate metabolism, energy, body temperature, weight, and mood — identifying both overactive and underactive thyroid conditions.
Anyone with fatigue, weight changes, mood changes, hair loss, cold/heat intolerance, irregular cycles, or family history of thyroid disease.
Sample Type
Blood draw
Fasting
Not required
Results In
1–3 business days · typical; varies by lab and draw day
Performed At
Quest or Labcorp
Your TSH with Reflex to Free T4 results will include values for each of the 2 biomarkers 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. Already have results? Analyze them with your AI assistant against our physician-reviewed ranges.
No fasting required. Best drawn in the morning when TSH is highest; stop high-dose biotin supplements for two days beforehand, and if you take levothyroxine, take it after the draw.
What can throw off this result
Physician-reviewed “Before your test” pages — what each factor does, for how long, and what to do about it.
TestWell orders the same TSH with Reflex to Free T4 the labs run for doctors' offices, so you can walk into any of these labs with our requisition — no doctor's visit, a licensed physician authorizes the order, and most patient service centers take walk-ins. The table shows each lab's own test code, the name printed on the requisition, what the lab charges on its own consumer site, and the price through TestWell at that lab (plus one $6 fee per order).
| Lab | Test code | On the requisition | Lab's own site | Through TestWell |
|---|---|---|---|---|
| Quest Diagnostics | — | “TSH with Reflex to Free T4” | not sold direct | $29.99 + $6 |
| Labcorp | — | “TSH with Reflex to Free T4” | not sold direct | $34.99 + $6 |
You choose the lab at checkout; the requisition is written for that lab and arrives by email within minutes. New York and New Jersey orders draw at BioReference. Lab-direct prices are read from the labs' public pages and re-checked regularly.
Where to get it near you: patient service centers by state and city · search by ZIP code
A TSH with Reflex to Free T4 test costs $29.99 at TestWell — $35.99 all-in, since the $6 lab processing fee is charged once per order and there is no draw or physician fee. Hospital outpatient labs typically bill around $120.00 self-pay. With insurance you pay your plan's negotiated rate against your deductible; TestWell's price is fixed before the draw and HSA/FSA-eligible.
| Where you order | Price | One test, all-in | Notes |
|---|---|---|---|
| TestWell (drawn at Quest) | $29.99 | $35.99 | Includes the one $6 lab processing fee, charged once per order |
| TestWell (drawn at Labcorp) | $34.99 | $40.99 | Labcorp's own cost for this test is higher; same order, same portal, same physician review |
| Hospital outpatient lab, self-pay (typical) | $120.00 | $120.00 | Reference figure; hospital charges vary widely by facility and are often higher |
Competitor prices are read from the linked public pages and re-checked regularly; the labs' sites may add taxes or change prices without notice.
Compare more: Quest Diagnostics price list · Labcorp price list · Quest vs Labcorp · Lab test price checker
Most TSH with Reflex to Free T4 results are available in 1–3 business days after your specimen arrives at the lab. You'll get an email the moment results are ready, with everything viewable in your TestWell portal.
Blood draw. A standard venous blood draw, collected at any Quest, Labcorp or BioReference patient service center — walk in with the requisition we email you, no appointment needed at most locations.
On TestWell, the TSH with Reflex to Free T4 is $29.99. Walk-in hospital labs typically bill $120 or more without insurance. Insurance is not required — pay one all-in price.
No fasting required for the TSH with Reflex to Free T4. No fasting required. Best drawn in the morning when TSH is highest; stop high-dose biotin supplements for two days beforehand, and if you take levothyroxine, take it after the draw.
The TSH with Reflex to Free T4 is available at Quest and Labcorp patient service centers nationwide. Order online at TestWell, pick your preferred lab, and we'll generate a digital requisition for the location closest to you.
Biotin supplements, ashwagandha and thyroid-support supplements and levothyroxine timing can change a TSH with Reflex to Free T4 test result without anything being wrong. Biotin supplements can falsely lower TSH and can falsely raise Free T4 — stop biotin ≥72 hours before the draw. 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. Levothyroxine timing can raise Free T4 — draw before the daily dose, then take it. Each is explained on our physician-reviewed "Before your test" pages; when one applies, remove it and retest.
Medically reviewed by Youmna DiStefano, MD · Last reviewed October 2026
TestWell Price
$29.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Frequently ordered together
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TSH with Reflex to Free T4
$29.99