Thyroid-stimulating antibodies in patients with autoimmune disorders

A radioreceptor assay was used to measure thyroid-stimulating antibody (TSAb) in 1) patients with Graves' disease with untreated hyperthyroidism, selected for absence of clinically significant eye disease; 2) patients with Graves' ophthalmopathy, with and without previously treated hyperthyroidism; 3) patients with other thyroid disorders; 4) patients with other autoimmune disorders; and 5) normal subjects. TSAb was detected in 14 of 15 (93%) patients with Graves' hyperthyroidism and in 10 of 16 (63%) patients with Graves' ophthalmopathy. Of the patients with Graves' ophthalmopathy, TSAb was detected in 9 of 10 patients who had once been hyperthyroid and in only 1 of 6 patients who had never been hyperthyroid (euthyroid Graves' disease). TSAb was detected in 1 patient with idiopathic Addison's disease (autoimmune adrenalitis) and in 1 patient with juvenile diabetes mellitus (both of whom were euthyroid), and borderline levels were found in 1 patient with Sjögren's syndrome and 1 patient with methyldopa-induced antired blood cell antibodies. TSAb was not detected in normal subjects or patients with other thyroid disorders. The conclusions are: 1) the test is very useful in the diagnosis of Graves' disease; 2) Graves' eye disease may be a frequently associated but separate disorder; and 3) because TSAb may be present in some euthyroid patients with other autoimmune disorders, TSAb production may occur primarily because of a disorder in the immune system.