Efficiency of radioiodine therapy in the adenoma and multinodular toxic goitre as alternative to surgery

Objective. To investigate the effect of radioiodine therapy of thyroid adenoma (TA) and toxic multinodular goitre (TMG) on function and thyroid volume. Materials and methods. Prospective study which includes 14 consecutive patients with TA and 15 with TMG treated with radioiodine and followed for two years. The therapeutic dose was fixed at 15 mCi for TA and 150 mu Ci x g of thyroid tissue/uptakes at 6 h (mean dose: 14.4 +/- 4.1 mCi) for TMG. Thyroid function and ecographic thyroid volume were determined before and at 1, 3, 6, 12 and 24 months. Results. 90% of patients with TA and 80% with TMG recovered euthyroidism at the third month. One patient with TA and three with TMG required two doses. The latter patients were the only ones with hypothyroidism at two years. The TA volume decreased from 20 +/- 8.5 ml to 10.4 +/- 8.1 ml at two years (p = 0.004). The extranodular thyroid volume did not change (initial: 16.4 +/- 10.4 ml versus 15.6 +/- 3.8 ml at the second year). The thyroid volume in TMG decreased from 66.5 +/- 28 ml to 39.8 +/- 13.5 ml at two years (p = 0.006). The largest reductions for TA and TMG were 54% and 38%, respectively, within the first six months. Only one patient with TA and another patient with TMG had their volumes transiently increased, lower than 10%. Conclusions. Therapy with radioiodine of TA and TMG achieves a rapid recovery of euthyroidism and a gradual decrease in thyroid volume with a low incidence of hypothyroidism, with no additional secondary effects. It has proved to be a valid alternative to surgical therapy.