TSH receptor, IgG antibodies (Anti-TSHR)
Why this test?
For differential diagnosis of hyper- and hypothyroidism syndrome.
To control the treatment of recurrence of Graves' disease and make its prognosis.
To give a forecast of the development of transient disorders of the thyroid gland function in newborns.
In what cases is it prescribed?
With symptoms of hyperthyroidism: irritability, restlessness, tremors, a feeling of interruptions in the work of the heart, oligoamenorrhea, weight loss, despite an increased appetite, sensitivity to heat, especially in the presence of ophthalmopathy (exophthalmos) and pretibial myxedema of the skin.
With an atypical clinical picture of Graves' disease: unexpressed signs of hyperthyroidism, uncertain palpable goiter, ophthalmopathy on the background of euthyroidism, unilateral ophthalmopathy.
With symptoms of hypothyroidism: weakness, drowsiness, impaired concentration and memory, weight gain despite reduced appetite, increased sensitivity to cold, etc.
When examining pregnant women with a history of surgical treatment of Graves' disease or treatment with radioactive iodine, as well as pregnant women receiving thyrostatic drugs.
When examining pregnant women with signs of hypothyroidism
Antibodies to TSH receptors (anti-pTTH) are a heterogeneous group of autoantibodies that interact with thyroid stimulating hormone (TSH) receptors. According to the type of effect on the function of the thyroid gland, anti-pTTH is divided into stimulating and blocking antibodies. Stimulating anti-pTTH repeatedly enhance the function of the thyroid gland, which leads to diffuse goiter and hyperthyroidism. Blocking anti-pTTH inhibit the action of TSH and lead to atrophy of the thyroid gland and hypothyroidism. Anti-rTTH mainly belong to IgG class immunoglobulins and penetrate through the placental barrier. Both variants can be detected in the blood of the same patient at the same time. They are the direct cause of Graves' disease and autoimmune thyroiditis, as well as transient disorders of thyroid gland function in newborns. Research on antibodies to TSH receptors is a diagnostic test that detects both stimulating and blocking antibodies in the blood.
Anti-rTTH is a clinical and laboratory marker of Graves' disease and is studied in the differential diagnosis of hyperthyroidism syndrome. The presence of anti-rTHG is not characteristic of other causes of hyperthyroidism, such as toxic nodular goiter, granulomatous thyroiditis, or administration of exogenous thyroxine. Stimulating anti-rTTH are detected in 85-100% of patients with Graves' disease and can serve as its diagnostic criterion. The concentration of anti-rTTH reflects the activity of the disease and is related to the severity of ophthalmopathy. The value of this test is especially great if the disease has an atypical clinical picture: signs of hyperthyroidism, uncertain palpable goiter, ophthalmopathy on the background of euthyroidism, unilateral ophthalmopathy. The concentration of anti-rTHG decreases with the appointment of antithyroid drugs, while a high rate of reduction of the titer indicates a positive response to treatment. The dynamics of anti-tSH can serve as a basis for correction of therapy, including the complete cancellation of antithyroid drugs. In 75-96% of cases of Graves' disease, blocking anti-rTHG is also detected. It should be noted that anti-rTHG is not a strictly specific test for Graves' disease and may also be detected in 10-15% of patients with Hashimoto's autoimmune thyroiditis.
Analysis of anti-rTTH plays an important role in the diagnosis of Graves' disease in pregnant women. The danger of Graves' disease during pregnancy is that anti-tSH overcomes the placental barrier and leads to hyperthyroidism in the newborn. Radionuclide scanning of the thyroid gland, one of the main ways of diagnosing Graves' disease, is not prescribed to pregnant women. In this situation, anti-tSH testing is a good alternative to thyroid scintigraphy. The concentration of anti-rTTH is measured in pregnant women with a history of surgical treatment of Graves' disease or treatment with radioactive iodine, as well as in women receiving thyrostatic drugs during pregnancy. As well as stimulating anti-rTTH, blocking antibodies cross the placenta and can cause transient hypothyroidism in the newborn. For timely diagnosis of autoimmune hypothyroidism in pregnant women, an anti-tSH test is performed.
In half of the cases of Graves' disease, after the end of the course of thyrostatic drugs, the disease relapses. When evaluating the prognosis of recurrence, several parameters are used, such as the size of the goiter, the age and gender of the patient, the presence of ophthalmopathy and the level of anti-tSH. A high level of anti-tSH is considered as an unfavorable prognostic factor.
Graves' disease and autoimmune thyroiditis can coexist with other autoimmune conditions, such as systemic lupus erythematosus, pernicious anemia, and rheumatoid arthritis. Therefore, with a positive result of the analysis for anti-tSH and the diagnosis of autoimmune thyroid gland disease, it is recommended to conduct additional laboratory tests to rule out concomitant pathology.