The short answer
Detects the antibodies that switch the thyroid on in Graves' disease — the most specific blood test for Graves' hyperthyroidism, measured from a standard blood draw. At TestWell it costs $114.99 plus a $6 lab processing fee, needs no fasting, and results post in 3–5 business days. Physician-authorized with no doctor's visit or insurance needed; draw at Quest.
TestWell Price
$114.99
+ $6 lab processing fee
Thyroid-stimulating immunoglobulins are antibodies that bind the TSH receptor and drive the thyroid to overproduce hormone. They are the cause of Graves' disease, and this assay measures their stimulating activity directly, which is why a positive TSI in someone with a low TSH and high thyroid hormones confirms Graves' as the cause rather than a toxic nodule or thyroiditis. Endocrinologists also use TSI to follow Graves' disease over time, to judge the likelihood of remission before stopping antithyroid medication, and during pregnancy in women with current or past Graves' disease, because high levels in the third trimester predict thyroid problems in the newborn. TSI is often ordered together with the TSH receptor antibody (TRAb) test: TRAb detects any antibody that binds the receptor, TSI specifically the ones that stimulate it. Not available through BioReference, so it cannot be collected in New York or New Jersey.
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
3–5 business days
Performed At
Quest
1 biomarker tested
Your TSI (Thyroid-Stimulating Immunoglobulin) 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 3–5 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. Stop high-dose biotin supplements at least 2 days before the draw.
A TSI (Thyroid-Stimulating Immunoglobulin) test costs $114.99 at TestWell — $120.99 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 $350.00 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) | $114.99 | $120.99 | Includes the one $6 lab processing fee, charged once per order |
| Hospital outpatient lab, self-pay (typical) | $350.00 | $350.00 | Reference figure; hospital charges vary widely by facility and are often higher |
Lab test codes: Quest test code 30551. 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 TSI (Thyroid-Stimulating Immunoglobulin) results are available in 3–5 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 TSI (Thyroid-Stimulating Immunoglobulin) is $114.99. Quest Direct lists comparable tests at $129. Walk-in hospital labs typically bill $350 or more without insurance. Insurance is not required — pay one all-in price.
No fasting required for the TSI (Thyroid-Stimulating Immunoglobulin). No fasting required. Stop high-dose biotin supplements at least 2 days before the draw.
The TSI (Thyroid-Stimulating Immunoglobulin) is available at Quest 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.
The TSI (Thyroid-Stimulating Immunoglobulin) test is Quest Diagnostics test code 30551. TestWell orders it under that code for $114.99 at Quest — no doctor's visit or insurance required, results in 3–5 business days. Codes verified against the labs' catalogs in 2026.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
TestWell Price
$114.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Frequently ordered together
Customers who ordered TSI (Thyroid-Stimulating Immunoglobulin) also added these for a more complete health picture.
Not sure where to start?
TSI (Thyroid-Stimulating Immunoglobulin)
$114.99