TSH receptor antibodies (TRAb)
Autoantibodies against the thyroid's TSH receptor, a marker in Graves' disease
Also known as
Definition
TSH receptor antibodies (TRAb; on German-language lab reports often TRAK) are autoantibodies against the docking site through which the hormone TSH controls the thyroid. A stimulating form, thyroid-stimulating immunoglobulins (TSI), prompts the thyroid to make more hormone. Raised levels can be a sign of Graves' disease, the most common cause of an overactive thyroid. The test complements TSH, T3 and T4 but does not make a diagnosis on its own.
| Parameter | Value |
|---|---|
| Unit | lab-dependent (number with cut-off; TSI test in % of basal activity) |
| Reference Range | A negative result or a value below the lab's cut-off is normal. For the TSI test, MedlinePlus gives values below 130% of basal activity as normal. Cut-offs and units differ by lab and test method; the reference range on your own report is what counts. Discuss your result with your doctor. |
Agree on your personal target range with your doctor.
↓ What a low value means
A negative result is the normal finding: no antibodies against the TSH receptor were found above the cut-off. Together with the other thyroid values, this may suggest that an overactive thyroid has a cause other than Graves' disease. Your doctor will interpret the result.
↑ What a high value means
A raised value may be related to Graves' disease, the most common cause of raised TSI. Very rarely, raised levels occur with hashitoxicosis, an overactive phase in Hashimoto's thyroiditis. A raised value may also be related to an overactive thyroid in a newborn (neonatal thyrotoxicosis). According to MedlinePlus, the more thyroid antibodies are found, the more likely an autoimmune thyroid disorder is. Discuss your result with your doctor.
When to test
TRAb are usually measured when TSH, T3 or T4 suggest an overactive thyroid and there are symptoms such as weight loss, fast heart rate, hand tremor, heat intolerance, trouble sleeping, bulging eyes or a goiter. In the last three months of pregnancy, the TSI test is used to estimate the risk of an overactive thyroid in the baby. Usually no preparation is needed.
Frequently asked questions
What is the difference between TRAb and TSI? +
TRAb is the umbrella term for antibodies against the TSH receptor. TSI are the stimulating form that prompts the thyroid to make more hormone. Depending on the lab, one test or the other is offered.
How do TRAb differ from TPO and thyroglobulin antibodies? +
TPO and thyroglobulin antibodies are mainly associated with Hashimoto's; TPO antibodies also occur in Graves' disease. TRAb and TSI are considered a sign of Graves' disease. Which antibodies are measured is decided by your doctor based on your symptoms and other values.
Why is the test done during pregnancy? +
According to MedlinePlus, the TSI test is used in the last three months of pregnancy to estimate whether Graves' disease or an overactive thyroid could occur in the baby. Whether the test is relevant for you is something to discuss with your doctor.
Does the antibody test replace a thyroid scan? +
Not in general. According to MedlinePlus, the TSI test is often done when there are signs of an overactive thyroid but a thyroid uptake and scan cannot be performed. Which examination makes sense is decided by your doctor.
TSH receptor antibodies (TRAb)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.