Thyroid adenylate cyclase stimulating immunoglobulins in thyroid diseases

The occurrence of serum immunoglobulins with capacity to stimulate thyroid adenylate cyclase (TSAb) was studied in seventy-two healthy volunteers and 120 unselected patients with various thyroid diseases. A high frequency of TSAb (82.5%, P less than 0.00006) was found in Graves' disease, while TSAb was present only in 13--20% of serum from patients with nontoxic nodular goitre, nontoxic diffuse goitre, toxic adenoma, toxic nodular goitre and myxoedema. These patients had low level of TSAb compared to patients with Graves' disease. In patients with Graves' disease there was no correlation between the level of TSAb and hormonal status except serum triiodothyronine (rs = 0.29, P less than 0.05), and no relation with eye involvement or presence of microsomal thyroid antibodies was found. The results indicate that the human thyroid adenylate cyclase assay system with 1 hour incubation periods is a sensitive method for detection of immunoglobulins with TSH-like capacity to stimulate the thyroid gland.