The prevalence of serum thyroid-stimulating immunoglobulins (T.S.I.) in a variety of thyroid diseases was determined in 96 patients and 35 normal controls. Significantly elevated levels of T.S.I. were found not only in patients with Graves' disease and Hashimoto's thyroiditis but also in those with non-toxic and toxic multinodular goitre, whereas patients with a single autonomously functioning thyroid nodule, with subacute thyroiditis, and with "hyperthyroiditis" had levels which did not differ from those in the controls. We postulate that non-toxic multinodular goitre, like Graves' disease, may result from increased circulating T.S.I., which in some cases may be present in sufficient concentration to cause thyrotoxicosis.
Adolescent Adult