Outcome of long-term antithyroid treatment of graves' disease in relation to iodine intake.

Seventy-seven patients with Graves' disease, with an average of 56 years of age were treated with carbimazole in the period 1968-1975. The duration of therapy was on an average, 17.9 months and the follow-up on an average, 28.5 months. Remission was found only in 32% of the patients. Data on the urinary iodine excretion from a total of 127 euthyroid controls and 15 patients with Graves' disease living in the same area were collected during the periods: 1962-1964, 1965-1968, 1971-1973 and 1972-1974. No significant difference was found in the urinary iodine excretion in the period 1962-1973 and no significant difference was found in the urinary iodine excretion between the patients with Graves' disease and the euthyroid controls. Our data demonstrate a high relapse rate following long-term treatment with anti-thyroid drugs in an area with relative low iodine intake.