Abstract: AIM: To explore the efficacy of ¹³¹I doses calculated by thyroid weight-dosage relevant formula(¹³¹I dosage per g thyroid tissue: μCi/g=100+thyroid weight) on therapy for Graves' hyperthyroidism with large goiter. METHODS: Randomly distributed 105 Graves' hyperthyroidism with large goiter patients into 3 groups, Thyroid weigh was calculated by weight formula of SPECT. ¹³¹I Doses of the first group patients calculated by fixed dosage, that was ¹³¹I dosage per g thyroid tissue : μCi/g=150uCi; ¹³¹I dosage of the second group patients calculated by weight-excision formula, that was D=[d×8×m(g) ]÷[1.6×highest thyroid iodine uptake ×T_1/2eff],d=m1÷m2×d0; d0 fixed to 55 Gy. ¹³¹I dosage of the third group patients calculated by thyroid weight-dosage relevant formula(¹³¹I dosage per g thyroid tissue : μCi/g=100+ thyroid weight). Comparing ¹³¹I Doses and frequency of ¹³¹I treatment for 3 groups patients when all 105 hyperthyroidism patients achieved normal thyroid function or hypothyroidism. RESULTS: ⑴ After the first ¹³¹I therapy, Thyroid function of The first group patients were 20 cases with hyperthyroidism, 10 cases with normal thyroid function and 5 with hypothyroidism; Thyroid function of The second group patients were 9, 20, 6 respectively; and the third group patients were 8, 18 , 9 respectively. ⑵ The doses of the first treatment of ¹³¹I were (20.9±6.0) mCi (the first group);25.9±11.8 (the second group) and 26.9±9.0 (the third group) respectively. ⑶ When all 105 hyperthyroidism patients achieved normal thyroid function or hypothyroidism, the mean ¹³¹I dose per patient were (31.5±16.0) mCi (the first group);30.1±18.9 (the second group) and 30.8±15.1 (the third group) respectively. CONCLUSION: ¹³¹I Doses calculated by thyroid weight-dosage relevant formula was a simple, feasible method. It can avoid the complex of weight-excision formula and could deserve of abroad clinical application.

Key words: ¹³¹I, large goiter, doses, Graves' hyperthyroidism, thyroid weight