[en] Full text: Radioiodine is being increasingly used in the treatment of hyperthyroidism. The primary reasons for choosing radioiodine therapy are its effectiveness, ease of administration, relatively low cost and paucity of side effects. Here we presented our experiences and outcome of radioiodine therapy in hyperthyroidism in a divisional referral centre.We retrospectively analyzed 203 patients receiving radioiodine therapy for hyperthyroidism in Centre for Nuclear Medicine and Ultrasound, Khulna during the period from July 1994 to June 2004. All the patients had clinical signs and symptoms of hyperthyroidism as well as elevated triiodothyronine (T₃), thyroxine (T₄) and suppressed thyroid stimulating hormone (TSH). T₃, T₄ and TSH were done in all cases. Radionuclide scan and ultrasound of thyroid gland, radioactive iodine uptake (RAIU), thyroid microsomal antibody (TMAb) and fine needle aspiration cytology (FNAC) was done in selected cases. We assessed all patients prior to radioiodine therapy. Elderly patients and all those with cardiac complications and severe hyperthyroidism were pretreated with a short course of antithyroid drug in full dosages until they were clinically and biochemically euthyroid. Ninety five patients were on antithyroid medication (Neomercazole) prior to radioiodine therapy. Antithyroid medication were stopped 3 days before radioiodine therapy and restarted 3 days later and continued for 1 to 2 months depending on patient's symptoms. The rest of the patients received either no treatment or beta-blocker prior to radioiodine therapy. Menstrual history was taken in female patients and pregnancy was excluded by ultrasonography in doubtful cases before administering radioiodine. The likely consequences of the treatment were fully explained to the patients and attendants, the usual precautions for radiation protection of the public and the necessity of the follow-up were discussed and verbal consent was taken before administering radioiodine. Radioiodine was given orally as Na ¹³¹I solution to all patients in modified fixed dose regime ranged from 5 mCi to 15 mCi. All the patients were advised to attend the centre if any complications arise and in regular follow up at 6 weeks, 3 months, 6 months, 9 months and 1 year and then annually. Clinical and biochemical evaluations were done in follow up visit. If the first dose was found to be ineffective in controlling the disease or hyperthyroidism persist, then the second dose, third dose or fourth dose was given after 6 months interval with proper clinical and biochemical evaluation. If even with fourth dose, hyperthyroidism was not controlled, the case was referred for surgical management. The amount of radioiodine given in the second dose and in subsequent third dose or fourth dose was same as first dose or higher. Early complications of radioiodine were only encountered when the patient attended the centre for such. During follow up, patients were classified as cured if the functional status was either euthyroid or hypothyroid within 1 year without further treatment of hyperthyroidism by antithyroid drugs or radioiodine. Patient was diagnosed as hypothyroid on the basis of clinical and biochemical criteria, including low T₄ and high TSH. Total 203 patients with hyperthyroidism treated with radioiodine were studied. Among 203, 117 were female and 86 were male with female male ratio of 1.4:1. The mean age of the patients was 38.38 10.42 years (ranged 16 years to 70 years). Among 203 cases, 190 (172 Graves' diseases, 8 solitary toxic nodule, 10 toxic multinodular goiter) patients attended regularly as per advice and 13 patients were lost to follow up. It was found that 18 patients became euthyroid within 3 months, 35 patients became euthyroid within 6 months, 19 patients became euthyroid within 9 months and 97 patients became euthyroid within 1 year. Thus the cure rate was found to be 88.95% (169/190). In 18 (9.47%) cases hyperthyroidism persisted with no clinical and biochemical improvement within 6 months in which 15 were Graves' disease, 1 solitary toxic nodule and 2 toxic multinodular goiter. After becoming euthyroidism, hyperthyroidism recurs in 3 (1.58 %) cases within 1 year. Recurrence of hyperthyroidism was also seen in 2 cases after 1 year of radioiodine treatment. These patients (persistent and recur cases) were treated with second dose and if needed third and/or fourth dose of radioiodine. Second dose was given in 23 cases, third dose given in 7 cases and fourth dose given in 2 cases. We referred 1 case for surgical treatment not for responding even with fourth dose of radioiodine. During our follow up period, 6 patients became hypothyroid within 3 months, 14 patients became hypothyroid within 6 months, 7 patients became hypothyroid within 9 months and 5 patients became hypothyroid within 1 year. Thus hypothyroidism within 1 year was found to be 16.84% (32/190). Other side effects such as iododerma were observed in 5 (2.63%) cases, radiation thyroiditis developed in 17 (8.95%) cases, thyroid storm developed in 2 (1.05%) cases. Out of 43 with ophthalmopathy, 2 (4.44%) deteriorated, 1 (2.32%) unchanged and the rest (93.02%) improved. New ophthalmopathy developed in 3 cases (3/147 i.e., 2.04%). None developed any malignancy or leukemia during our follow up period. We conclude that our experience revealed similar outcomes as have been reported by other workers with the exception of iododerma, one of the early complications of radioiodine therapy that we noticed during our follow up period. (author)