Recombinant human thyrotropin-stimulated radioiodine therapy of nodular goiter allows major reduction of the radiation burden with retained efficacy

Context and Objective: Stimulation with recombinant human TSH (rhTSH) before radioiodine ((131)I) therapy augments goiter volume reduction (GVR). Observations indicate that rhTSH has a preconditioning effect beyond increasing thyroid (131)I uptake. We test the hypothesis that an equivalent GVR might be obtained by an absorbed thyroid dose well below what has been used previously. Patients and Design: In a double-blinded setup, 90 patients (78 women; median age, 52 yr; range, 22-83) with a nontoxic nodular goiter (median size, 63 ml; range, 25-379 ml) were randomized to either 0.1 mg rhTSH (n = 60) followed by a thyroid dose of 50 Gy or placebo followed by 100 Gy (n = 30). Results: At 12 months, the mean relative GVR in the placebo and the rhTSH group was identical (35 +/- 3%; P = 0.81). The median administered (131)I-activity was 170 MBq (45-1269) in the rhTSH group and 559 MBq (245-3530) in the placebo group (70% reduction, P < 0.0001). According to the official radiation regulation, hospitalization was required in 14 patients in the placebo group vs. one patient in the rhTSH group (P < 0.0001). In both groups, goiter-related symptoms were effectively relieved in the majority of patients. The prevalence of myxedema (10%) did not differ among groups. Conclusions: This is the first study to demonstrate that rhTSH not only increases the thyroid (131)I uptake, but per se potentiates the effect of (131)I-therapy, allowing a major reduction of the (131)I-activity without compromising efficacy. This approach is attractive in terms of minimizing posttherapeutic restrictions and in reducing the potential risk of radiation-induced malignancy.