Thyroid
TSH-receptorantistoffen
Antibodies that drive the thyroid to make too much hormone; they show Graves' disease in an overactive thyroid.
Everything about this testWhat it measures
The thyroid has receptors on which the hormone TSH from the pituitary gland acts. In Graves' disease, the immune system makes antibodies against this TSH receptor (TRAb). These act just like TSH and drive the thyroid to make too much thyroid hormone. Rarely, the antibodies actually inhibit the thyroid. The test measures the amount of these antibodies in the blood.
- Graves' disease as the cause of an overactive thyroid (hyperthyroidism)
- Increased risk of thyroid problems in the unborn child, in pregnant women who have or have had Graves' disease
High
According to the Dutch GP guideline (NHG), detectable TSH receptor antibodies in an overactive thyroid are proof of Graves' disease, an autoimmune disease that mainly occurs in young and middle-aged women. Symptoms that go with it are palpitations, restlessness, trembling, heavy sweating, trouble with heat and weight loss; sometimes also eye symptoms. After successful treatment, the antibodies can remain present for a long time. During a pregnancy, they can stimulate the child's thyroid via the placenta, even if the mother herself has no symptoms. Slightly raised values sometimes also occur in other autoimmune diseases without Graves' disease.
Low
A negative or low value is normal. In an overactive thyroid, a negative result makes Graves' disease less likely; other causes then come into view, such as a thyroid with nodules that make hormone independently, a temporary inflammation of the thyroid, or medicines.
Preparation
- Do you take biotin (vitamin B8, often in hair and nail supplements)? Stop at least 2 days before the sample is taken, or 4 days for a high dose.
If your result is abnormal
With detectable antibodies and an overactive thyroid, the GP discusses treatment or refers you to the internist (specialist in internal medicine). According to the NHG guideline, pregnant women with detectable antibodies are referred to the gynecologist and the internist.
Reliability
According to the Dutch GP guideline (NHG), the test is intended for people in whom an overactive thyroid (low TSH, raised free T4) has been established or is suspected, to show Graves' disease, and for pregnant women with a history of Graves' disease. In people with a normal TSH, the test has little meaning. Laboratories in the Netherlands use different tests with different cut-off values.
Limitations
- Cut-off values differ between laboratories and measurement methods; only compare results from the same laboratory.
- After treatment of Graves' disease, the antibodies can remain detectable for a long time, even with normal thyroid function.
- Slightly raised values are not specific and sometimes occur in other autoimmune diseases.
How common is this
An overactive thyroid affects about 1 in 100 adults in the Netherlands, more often women. According to the Dutch GP guideline (NHG), Graves' disease is the cause in 70 to 80 in 100 of them.
Who is this useful for
Useful with an established or suspected overactive thyroid, to find the cause, and during a pregnancy or when planning a pregnancy in women who have or have had Graves' disease. In people without symptoms and with a normal TSH, the result says little; with symptoms, TSH first shows whether the thyroid is overactive.
Downsides and risks
- A slightly raised value with normal thyroid function can cause worry and follow-up testing without Graves' disease being present.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results