RESUMO
Forty-eight patients with diffuse toxic goiter (Graves's disease) were treated with radioactive iodine in a dose of 5.3-30.0 mCi. A special formula considering the volume of the thyroid and post-24-hour capture of the diagnostic activity of radioactive iodine was used to calculate the optimum therapeutic activity. As a result, specific therapeutic activity (STA) correlated with specific activity and with the volume of thyroid. The high rate (33.3%) of recurrent thyrotoxicosis was observed when the calculated STA was less than 0 3 mCi/ml and reduced to 11.1% if a greater activity was applied. The use of the standard activity of radioactive iodine (10mCi) with a thyroid volume of up to 40 ml, as compared to that calculated by the formula results in the similar rate of ineffective radioiodine therapy for thyrotoxicosis at a lower incidence of euthyrosis.