The incidence of recurrence and hypothyroidism following treatment with antithyroid drugs, surgery or radioiodine in all patients with thyrotoxicosis in Malmö during the period 1970-1974.

The incidence of recurrence and of hypothyroidism was determined in all new patients treated for thyrotoxicosis during the period 1970-1974 in an unselected, well-defined urban population. A total of 309 patients were followed up for a median time period of 108 (1-192) months. There was a cumulative incidence of 51% recurrence in patients who were treated with antithyroid drugs for Graves' thyrotoxicosis, whereas after surgery or radioiodine treatment there were few recurrences, but 32% and 78% cumulative incidences of hypothyroidism. There were no recurrences after surgery or radioiodine treatment in patients with toxic multinodular goitre or solitary toxic adenoma, but 29% and 40% cumulative incidences of hypothyroidism following radioiodine treatment. Late hypothyroidism occurred after surgery for Graves' thyrotoxicosis, and in all groups treated with radioiodine. Thus it is advisable that all patients with Graves' thyrotoxicosis, regardless of treatment, and all patients with toxic multinodular goitre or solitary toxic adenoma treated with radioiodine, should be followed up for many years, and probably for life.