Hypothyroidism preceding hyperthyroid Graves' disease in two children.

Two children with acquired hypothyroidism developed hyperthyroid Graves' disease which was difficult to control. The cause of hypothyroidism was autoimmune thyroiditis in one case, in the other, autoimmune thyroiditis was suspected but not confirmed. Both children had thyrotrophin-binding inhibiting immunoglobulins (TBII) in their sera. The TBII index was very low, in one of them even during the hypothyroid phase. It is suggested that TBII reflect not only thyroid-stimulating, but also other thyrotrophin receptor antibodies.