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TSH receptor antibodies
The antibodies that cause Graves' disease. They confirm the diagnosis, predict relapse, and matter in pregnancy.
Other names: TRAb, TSI, thyroid-stimulating immunoglobulinSection: Thyroid
Updated: August 31, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortTSH receptor antibodies stimulate the thyroid to overproduce hormones in Graves' disease. Some assays report activity relative to a baseline (typical cutoff up to 130% of basal activity); others report a concentration. They are interpreted with TSH and free T4.
Reference ranges
Group
Reference range
Bioassay (stimulation) — typical range (international reference, not a national standard)
< 130% of basal activity
Result
negative / positive by the laboratory's cutoff
Cutoff from the MedlinePlus Medical Encyclopedia (international reference, not a national standard). Assay formats differ — the report's own reference applies. Reference ranges vary between laboratories and assays — use the range printed on your own lab report.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
A rough comparison with a typical range, not a diagnosis. Reference ranges vary between laboratories — check the range on your own report and let a clinician interpret the result.
What this marker is
These antibodies mimic TSH and switch the thyroid into overdrive. Their presence distinguishes Graves' disease from other causes of hyperthyroidism without a radioactive scan.
Titers fall during antithyroid drug therapy, and a high level at the end of treatment predicts relapse. In pregnancy, high levels can cross the placenta and affect the fetus — an important reason for monitoring.
When it is high
Graves' diseaseThe defining cause of hyperthyroidism with positive TRAb; the test confirms the autoimmune mechanism.
Risk of relapseA high titer at the end of antithyroid treatment predicts recurrence.
Pregnancy riskHigh maternal levels can cause fetal and neonatal hyperthyroidism — levels are monitored in the second half of pregnancy.
When it is low
Expected findingMost healthy people and most patients with other causes of hyperthyroidism are negative.
What can skew the result
These factors can shift the value without any disease — worth considering before a retest:
Antithyroid drug therapyPregnancyPhase of Graves' disease
How to prepare
Blood from a vein; no special preparation.
When a retest makes sense
During treatment of Graves' disease — every few months on the endocrinologist's schedule, and before stopping therapy.
Who usually reviews this result
A result outside the reference range is usually reviewed by: an endocrinologist. Bring your lab report and any previous results to the appointment.
Names used on lab reports
Your report may use any of these names: TRAbTSITSH receptor antibodiesThyroid-stimulating immunoglobulin
Units
Measured in: IU/L
Several markers on your report?
See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.
A positive result with hyperthyroidism confirms Graves' disease and guides the choice between drugs, radioiodine, and surgery — made by the endocrinologist.
Why measure TRAb before stopping medication?
A normalized titer lowers the chance of relapse after withdrawal; a high titer warns against stopping.
Can TRAb be positive with normal thyroid function?
Occasionally, early or after treatment — the antibody then serves as a marker to watch rather than an immediate problem.
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