Treatment of hyperthyroidism with radioiodine: effects of administered close on complications and thyroid junction

Background: Radio-iodine is a definite therapy for Graves disease hyperthyr oidism. However, the optimal dosage is still debatable. Aim: To assess the effects of different radioiodine doses on thyroid function and complication s in patients with hyperthyroidism. Material and methods: A retrospective a nalysis of 139 patients with hyperthyroidism, treated with radioiodine betw een 1988 and 1998. Radio iodine dose used was classified as low (<10 mCi), intermediate (10-14.9 mCi) or high (greater than or equal to 15 mCi). Resul ts: Thirty five patients were treated with low doses, 33 with intermediate doses and 71 with high doses. Ther were no differences between these patien ts in age, disease severity, frequency of post treatment euthyroidism or co mplications. Patients treated with low doses had a higher frequency of pers istent hyperthyroidism than patients treated with high doses (25.7 and 4.2% respectively, p<0,001). Likewise, the frequency of subsequent hypothyroidi sm was 60% in patients treated with low doses and 84.5% of those with high doses, in whom it also appeared earlier. Associated complications were clin ically irrelevant. In seven patients, Graves ophtalmopathy progressed after treatment, but this progression was not associated with the dose used. Con clusions: Radio iodine in high doses is useful, safe and effective for the treatment of Graves hyperthyroidism.