Antibodies to the thyrotropic hormone receptor

Thyroid stimulating hormone receptors Represent the membrane structures of thyrocytes. It is they that are linked to the TSH produced by the pituitary gland. These receptors provide the biological action of TSH. It is observed in Graves' disease (diffuse toxic goiter) TSH Receptor Antibody (TRAB) Level increase.

Antibodies against the TSH receptor are heterogeneous in nature, they can act differently and can be of different types:

• Stimulating Antibodies (TSH-Stimulating Blocking Antibodies, TSAb) - Imitation of TSH action after binding to the receptor; Their presence leads to the development of hyperthyroidism;
• Antibodies that inhibit TSH receptor binding (TBII, thyrotropin binding inhibitor antibodies) - Inhibits the binding to the TSH receptor and its action on the thyroid gland, due to which the gland can not be adequately stimulated; It is usually associated with Graves' disease, but can be detected in Hashimoto's thyroiditis and other diseases of the thyroid gland;
• Blocking Antibodies (TSH Blocking Autoantibodies, TBAb) - After binding to receptors, they suppress the thyroid gland and cause its hypofunction.

TRAb is found in 80% of patients with untreated Graves' disease. Rarely, antibodies may be detected in patients with Hashimoto's thyroiditis and primary myxedema.

Persistence of TRAb in patients receiving antithyroid medications is a risk factor for disease recurrence after discontinuation of treatment.

Because TRAb belongs to the IgG class, placental transmission from mother to fetus is possible. If patients with Graves' disease have high concentrations of TRAb in the third trimester of pregnancy, the fetus has a risk of developing neonatal hyperthyroidism associated with birth defects and mortality.

When should we test for anti-thyroid hormone receptor antibodies?

1. Differential diagnostics:

• Thyrotoxicosis during pregnancy;
• Differential diagnostics of different variants of diffuse toxic goiter and destructive thyrotoxicosis;
• Subclinical thyrotoxicosis with diffuse goiter;
• Endocrine ophthalmopathy on the background of euthyroidism;
• Multinodular toxic goiter with "hot" nodules;
• Differential diagnostics of neonatal hypothyroidism caused by maternal antibodies;
• Differential diagnostics of neonatal thyrotoxicosis (thyrotoxicosis with possible damage to the fetal thyroid gland due to transplacental transmission of antibodies).

2. Prediction of recurrence of diffuse toxic goiter

How to prepare for the test?

The test should be performed on an empty stomach.

Research material

Venous blood

Possible interpretation of the results

TRAB levels increase:

• In 85-95% of cases of diffuse toxic goiter (Graves' disease);
• Other forms of thyroiditis.

Resources

https://www.synevo.ro/shop/anticorpi-anti-receptor-tsh-trab/
https://spravochnik.synevo.ua/ru/thyrioidnaia/antitela-receptori-TTG.html
https://www.synevo.bg/at-anti-tsh-retseptor-trab/