¹³¹I treatment of toxic nodular goiter under combined thyrostatic-thyromimetic medication is at low risk of late hypothyroidism.

131I treatment of toxic nodular goiter under combined thyrostatic-thyromimetic medication is at low risk of late hypothyroidism Paghera B. 1, Panarotto M. B. 1, Maira G. 1, Magri G. C. 1, Bertagna F. 2, Bosio G. 2, Rossini P., De Agostini A. 3, Savelli G., Lucchini S. 2, Giubbini R. 1,2 1 Unit of Nuclear Medicine, Civilian Hospitals of Brescia, Brescia, Italy; 2 Unit of Nuclear Medicine, University of Brescia, Brescia, Italy; 3 Department of Health Physics, Civilian Hospitals of Brescia, Brescia, Italy AIM: Treatment of toxic nodular goiter with 131I is a first-line therapy for hyperthyroidism. To avoid a thyrotoxic storm, 131I is usually administered after pretreatment with antithyroid drugs, with thyroid-stimulating hormone (TSH) increase and functional recruitment of inhibited normal tissue. Therefore, both autonomous nodule(s) and normal tissue are irradiated. This may be a reason for late hypothyroidism occurring in 15-25% of patients. This study aimed at assessing different pretreatment modalities with combined methymazole and triiodothyronine, achieving euthyroidism with suppressed TSH. METHODS: After diagnosis of autonomously functioning toxic nodule, patients were subjected to thyrostatic medication. Two months later, TSH was checked; if >0.5 mU/L triiodothyronine treatment was associated. After 2 more months, if the TSH level was suppressed, patients received 131I-therapy. A total of 149 patients were consecutively enrolled, 41 of whom with uninodular and 108 with multinodular goiter. They were evaluated at diagnosis, pretreatment, 3 and 6 months after therapy and at late follow-up (6.8±4.2 years; range: 1-22 years). RESULTS: Administered activity was calculated according to 131I uptake and gland weight. Methymazole was discontinued 6 days before treatment and T3 was maintained until administration of 131I-therapy. Euthyroi-dism was achieved in 88% of patients. At late follow-up, subclinical hypothyroidism was observed in 10 patients (6.7%) and overt hypothyroidism in 5 patients (3.3%). No pathological consequences or side effects of 131I-therapy were found during the 6.8±4.2 year follow-up period. CONCLUSION: Treatment of toxic nodular goiter with 131I-therapy, under combined thyrostatic-thyromimetic treatment is a simple, safe, well-tolerated, and effective procedure.