RESUMO
There is little consensus regarding the most appropriate dosage regimen for radioiodine treatment in Graves' disease. The authors evaluated the efficacy of low fixed dose (5mCi) of radioiodine therapy, in terms of its cure rate and promptness of control, as well possible factors influencing the outcome. One hundred and twenty five consecutive patients with Graves' disease with persistent disease activity despite receiving carbimazole were treated with 5 mCi fixed dose of I131. Patients, who remained hyperthyroid at 1 year, received a second dose of 7.5 mCi of I113. After first dose 73.6% were cured (36.8% hypothyroid and 36.8% euthyroid), while 26.4% patients did not respond. Those who achieved cure had significantly lesser goiter size (84.6% with grade I goiter and 70.7% with grade II) and had received significantly shorter duration of prior carbimazole therapy (22 +/- 10 months versus 63 +/- 27 months) (p < 0.01). Age, sex, baseline T3, T4, 24 hour I131 uptake did not affect the cure rate. Mean time to response was 7 +/- 4 months. One hundred and three (82.4%) patients were cured after 2 doses while only 22 (17.6%) were nonresponsive. Hence, low fixed dose (5mCi) radio active iodine (RAI) therapy seems to be effective in Graves' disease particularly in patients with small sized goiter and short duration of pretherapy with thionamides.