Objective: Evaluating the outcome of radioiodine therapy to early reveal hypothyroidism. Subjects: 98 patients with Graves' disease (Basedow), including 78 females and 20 males, had been treated by radioiodine (I-131) at. the Nuclear Medicine and Oncology Center - Bach Mai Hospital, were examined hypothyroidism following treatments. Results: 1- The efficacy of radioiodine therapy: average dose is 6.4 percent 1.8 mCi (3.5-11 mCi). Average time of treatment is 1.3
2- The rate of cure patients (euthyroid) after the first treatment is 75.5 percent, after the second treatment: 15.3 percent and after the third: 9.2 percent. After three radioiodine treatments, 100 percent patients were free from hyperthyroidism. As 6-12 months post treatments, clinical symptoms such as tremor of hand, warm and moist skin, bulging eyes, disorders of digestive system, goiter, arrhythmia were reduced or disappeared. The hypothyroid patients had lower thyroid hormone concentrations, higher TSH concentrations, and lower I-131 thyroid uptake
3- At one year and 7.9 years post treatments, the inddence of hypothyroid patients is 4 percent and 12.2 percent, respectively. The annual cumulative rate of hypothyroidism is 1.57 percent. Conclusions: Radioiodine therapy is a highly effective treatment for Graves' disease and the rate of hypothyroidism accounted for a small proportion. The hypothyroidism is easily treated with thyroid hormone therapy.