Laboratory evaluation of graves’ disease
Graves’ disease is a form of hyperthyroidism that occurs when circulating antibodies that mimic thyroid-stimulating hormone (TSH) stimulate the thyroid gland, causing a hyperthyroid state. In 1956, Adams and Purves reported on a patient with Graves’ disease whose blood contained a factor that caused stimulation of animal thyroid (1). This factor’s effect was much longer than TSH and was called long-acting thyroid stimulator (LATS). Kriss subsequently demonstrated in 1964 that this compound had the structure of an IgG immunoglobulin and could be neutralized by thyroid tissue (2). These findings gave rise to the concept that a circulating antibody mimicked TSH and caused Graves’ disease. This antibody is directed against the TSH receptor on the thyroid follicular cell and can now be measured. The antibody is referred to as thyroid-stimulating immunoglobulin (TSI) or TSH receptor antibody (TRAb).