[Treatment of hyperthyroidism caused by Graves' disease or toxic multinodular goitre by radioiodine: over 80% cure retrospectively after one calculated dose]. / Behandeling van hyperthyreoïdie door de ziekte van Graves of toxisch multinodulair struma met jodium-131: retrospectief ruim 80% genezing na één berekende dosis.

OBJECTIVE: Assessment of the results of radioiodine therapy for hyperthyroidism one year after treatment. DESIGN: Retrospective study of patient reports and a literature search. METHOD: Data were collected from 159 patients with Graves' disease or toxic multinodular goitre who had been treated with a calculated dose of radioiodine (131I) during a four-year period (1994-1998) at the Bronovo Hospital, The Hague, the Netherlands. Percentages of hypothyroidism, euthyroidism and hyperthyroidism one year after the treatment were compared with results from the literature. RESULTS: Of the patients treated for Graves' disease 42% were hypothyroid, 38% were euthyroid and 20% were hyperthyroid one year after radioiodine therapy. For patients with toxic multinodular goitre the figures were 10%, 78% and 12% respectively. These results were comparable with those found in the literature. Two factors influenced the outcome of therapy in patients with Graves' disease: patients with persistent hyperthyroidism were on average younger and low thyroid weight increased the chance of hypothyroidism. Whether the hyperthyroidism was permanent or transient could only be established in less than half of all patients with hormone substitution after treatment, as the substitution had already been started in the first six months. CONCLUSION: One calculated dose of radioiodine can effectively cure hyperthyroidism in over 80% of the patients. It is recommended that an effort is made to discontinue radioiodine treatment after one year so as to exclude transient hypothyroidism and unjustified hormone substitution.