Relevance of cause of hyperthyroidism in determining its management

We analyzed the relapse rates of hyperthyroidism and prevalence rates of hypothyroidism after partial thyroidectomy and radio-iodine therapy in patients with Graves' disease and toxic multinodular goitre. In achieving euthyroidism, partial thyroidectomy was more effective in patients with Graves' disease (P less than 0.02). In patients with toxic multinodular goitre, radio-iodine therapy was more successful (P less than 0.05). Relapse of hyperthyroidism occurred more often in the radio-iodine group (P less than 0.02), mainly in patients with Graves' disease, and was seen sooner after radio-iodine therapy than after surgery (P less than 0.0001). Patients with toxic multinodular goitre, developed hypothyroidism more often after partial thyroidectomy than after 131I (P less than 0.01). In contrast, in patients with Graves' disease, hypothyroidism occurred more often after radio-iodine therapy than in the toxic multinodular goitre group (P less than 0.02). We conclude that the cause of hyperthyroidism strongly influences the efficacy of the therapeutic regimen.