TRak Blood Test: TSH Receptor Antibodies for Graves' Disease
TSH receptor antibodies (also called thyrotropin receptor antibodies or TRak) are autoantibodies that bind to the TSH receptor on thyroid cells. Unlike TSH, which stimulates the thyroid in a regulated manner, these antibodies can cause uncontrolled thyroid hormone production, leading to hyperthyroidism. The TRak test is the gold standard for confirming Graves' disease, the most common autoimmune cause of an overactive thyroid.
Why Test TRak?
TRak testing is indicated when hyperthyroidism is suspected or confirmed and the underlying cause needs to be identified. It is also useful for monitoring antibody levels in patients with known Graves' disease, during pregnancy (elevated TRak can cross the placenta and affect the foetus), and when there is a family history of hyperthyroidism with suggestive symptoms. It forms an important component of a comprehensive thyroid antibody panel.
What Do High TRak Levels Mean?
A positive TRak result indicates the presence of TSH receptor antibodies, strongly suggesting Graves' disease. In this condition, the antibodies stimulate the thyroid to overproduce hormones, leading to elevated T3 and T4 and suppressed TSH. Symptoms include unintended weight loss, rapid heartbeat, tremors, anxiety, heat intolerance, and an enlarged thyroid (goitre).
What Do Low TRak Levels Mean?
A negative TRak result means TSH receptor antibodies were not detected. This makes Graves' disease unlikely as the cause of thyroid dysfunction, though some patients with autoimmune thyroid disease may not have detectable antibodies at the time of testing. Retesting may be appropriate if clinical suspicion remains high.
Symptoms to Watch For
- Unintended weight loss despite normal or increased appetite
- Rapid or irregular heartbeat and palpitations
- Nervousness, anxiety, and irritability
- Tremors in the hands and fingers
- Increased sweating and heat intolerance
- Enlarged thyroid gland (goitre)
- Changes in menstrual patterns
- Fatigue and muscle weakness
- Difficulty sleeping
- Thinning skin and brittle hair
Who Should Get Tested?
- People with confirmed or suspected hyperthyroidism
- Patients with Graves' disease monitoring antibody levels
- Pregnant women with a history of Graves' disease
- Individuals with a family history of hyperthyroidism
- Anyone with hyperthyroid symptoms even if standard tests are borderline
How to Prepare for Your Test
No advance preparation is required. Do not take thyroid medication until after the blood draw. Test before 10 am for optimal results. Avoid vigorous exercise beforehand. Bring valid identification. If you take a supplement containing biotin (often sold for hair and nails), pause it for two days before the test, as high doses can distort the result.
Order Your Blood Test
Test your TRak levels with an accredited Swedish laboratory. Results within days, reviewed by Wellth.
Frequently Asked Questions
What is the difference between TRak and TPO antibodies?
Can TRak antibodies affect pregnancy?
Do TRak levels predict Graves' disease severity?
Reviewed by
Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
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The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.