T4, Free

Quest#866
LabCorp#001974
17 ordering services comparedPrices last checked 3 days ago

The Free T4 test measures the amount of unbound (free) thyroxine in the blood. Thyroxine (T4) is a hormone produced by the thyroid gland. Most T4 in the blood is attached to proteins, while a small portion circulates freely and is available for the body to use. This test measures only the free portion, which reflects thyroid activity independent of protein levels. This test is used to help evaluate how well the thyroid gland is functioning. It is often ordered along with a TSH (thyroid-stimulating hormone) test to help assess conditions such as an overactive or underactive thyroid, and to monitor people who are receiving treatment for thyroid disorders.

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How much does a T4, Free test cost?

The cheapest self-pay T4, Free test is $5.52 at Mito Health, out of 17 ordering services compared. The highest listed price is $89.00 at LabCorp OnDemand, a difference of $83.48. It is Quest test code 866 and LabCorp test code 001974. Prices are self-pay cash rates read from each service’s own public catalog, last verified 3 days ago.

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Mito Health · $5.52
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T4, Free self-pay prices by ordering service, last checked 3 days ago
Ordering ServicePriceOrder
Mito Health✓ Best Pricechecked 3 days ago$5.52$3.94 for members ($9/mo membership)Order
Good Labschecked 3 days ago$6.00Order
AlgoRxchecked 3 days ago$7.00Order
DrSayschecked 3 days ago$9.99Order
Jason Healthchecked 3 days ago$10.00Order
Marek Diagnosticschecked 3 days ago$13.00Order
Anabolic Insightschecked 3 days ago$14.00$14.00 via LabCorp also availableOrder
Own Your Labschecked 3 days ago$17.00Order
DirectLabschecked 3 days ago$36.00Order
HealthLabs.comchecked 3 days ago$39.00Order
Walk-In Labchecked 3 days ago$39.00Order
Request A Testchecked 3 days ago$39.00Order
Discounted Labschecked 3 days ago$63.00Order
True Health Labschecked 21 days ago$69.00Order
Private MD Labschecked 3 days ago$70.00Order
Personalabschecked 3 days ago$77.00Order
LabCorp OnDemandchecked 3 days ago$89.00Order

These are online lab ordering services — not the physical draw site. Once you purchase a requisition, you visit a nearby Quest or LabCorp patient service center for your blood draw. Prices are self-pay cash rates and may vary by location.

Guides about T4, Free

Plain-English explanations of what this test measures and how it's done.

What Do TSH, T3, and T4 Mean on a Thyroid Panel?
A thyroid panel usually reports three things: TSH, a signal from your pituitary gland, and T4 and T3, the two hormones the thyroid actually makes. TSH tells the thyroid how hard to work, so it often shifts before the hormone levels do. Read together, the three numbers show whether the gland and its control signal are in step.
What Blood Tests Relate to Autoimmune Conditions?
No single blood test diagnoses an autoimmune condition. Testing usually combines broad markers, such as an ANA test, CRP or ESR and a complete blood count, with antibody tests aimed at one organ, like thyroid peroxidase antibodies for the thyroid. Which tests make sense depends on symptoms, so the choice sits with a clinician.

T4, Free: common questions

How much does a T4, Free test cost without insurance?

The lowest self-pay price we track for T4, Free is $5.52 at Mito Health, across 17 ordering services; the highest is $89.00. You pay the ordering service directly, and no insurance is involved. Prices were last verified on September 28, 2026.

Do you need a doctor's order for a T4, Free test?

No. Every ordering service listed on this page includes the physician order with the purchase, so you can buy T4, Free yourself and take the requisition to the lab. Your results come back to you — what they mean is a conversation for you and a clinician.

Where is the blood drawn for a T4, Free test?

At a Quest Diagnostics or LabCorp patient service center, depending on which laboratory the ordering service you pick uses. You choose the location and time after you order. LabTestCompare does not draw blood, run tests, or issue results — we only compare what each service charges.

Can you use health insurance for a T4, Free test?

No. Every price on this page is a self-pay price paid directly to the ordering service, and none of these services bill insurance. If you want T4, Free billed through your plan instead, that goes through your own provider — which is a separate route with its own cost, and worth comparing against the prices here.

Is this the same T4, Free test a doctor would order?

Yes — it is the same assay, identified by the same laboratory order codes: Quest #866 and LabCorp #001974. Every price on this page is matched to that code, which is how we can say the services are being compared on an identical test rather than on similarly named products.

How long do T4, Free results take?

That is set by the laboratory rather than by us. Routine blood tests are commonly back within a few business days and specialized assays take longer; the ordering service states the expected turnaround for T4, Free before you buy, and delivers the result to you directly.

Compiled by the LabTestCompare editorial team. Prices are collected from each ordering service’s own published catalog and re-checked on a schedule — see our editorial policy for how we source and correct them. Prices on this page were last verified .

Background reading on lab testing: MedlinePlus: Lab Tests (NIH) · CDC. This page is a price comparison, not medical advice — see our medical disclaimer.