Antibodies to TSH receptor (Anti-TSHR)
The anti‐TSH receptor determination is used as an aid in the differential diagnosis of Graves' disease.
Hyperthyroidism in Graves' disease (autoimmune hyperthyroidism) is caused by autoantibodies to the TSH receptor (TSHR), and measurement of these TSHR antibodies (TRAb) can be useful in disease diagnosis and management. The majority of TSH receptor antibodies mimic the action of TSH. Because they are not controlled by the negative feedback system, the stimulation of the thyroid often leads to the clinical thyrotoxic state of Graves' disease.
Indications for TRAb determination include:
▪ the detection or exclusion of autoimmune hyperthyroidism and its differentiation from disseminated autonomy of the thyroid gland. The presence of TRAb indicates that the patient's thyrotoxicosis is of autoimmune etiology rather than due to toxic nodular goiter. Because the aim of treatment for Graves' disease may differ from the treatment of other forms of thyrotoxicosis, an initial TRAb determination is clearly of value.
▪ monitoring the therapy of Graves' disease patients and prediction of relapse, thereby constituting an important decision-making aid in the management of the treatment. TRAb levels tend to fall during antithyroid drug therapy for Graves' disease. Low levels or the absence of TRAb after a course of drug treatment may indicate disease remission, and therefore the withdrawal of therapy can be considered.
▪ TRAb measurement during the last trimester of pregnancy. Because TRAb are IgG‐class antibodies, they cross the placenta and can cause neonatal thyroid disease. The measurement of TRAb during pregnancy in patients with history of thyroid disease is therefore important in assessing the risk of thyroid disease in the neonate.
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