Recombinant human TSH increases the efficacy of a fixed activity of radioiodine for treatment of multinodular goitre

Context: High doses of ¹³¹I are usually needed in the treatment of multinodular goitre (MNG) for effective thyroid volume (TV) reduction. Recombinant human thyroid-stimulating hormone (rhTSH) is an adjuvant to enhance ¹³¹I uptake, allowing a decrease in radiation activity and enhancing ¹³¹I efficacy. Objective: To evaluate whether rhTSH increases the efficacy of a fixed activity of ¹³¹I for the treatment of MNG. Design: Two-year, observational, placebo-controlled study. Setting: Patients received 0.1 mg rhTSH (A), 0.005 mg rhTSH (B) or placebo (C). A fixed activity of 1.11 GBq of ¹³¹I was administered 24 h after rhTSH or placebo. Patients: A total of 28 outpatients (26 females and two males) with MNG. Measurements: TSH, free T4, T3, thyroglobulin (Tg) and TV. Results: Basal radioactive iodine uptake and TV values were comparable among all groups. After rhTSH or placebo, peak levels of TSH, free T4, T3 and Tg were higher in A than in B or in C (p < 0.05). Hyperthyroidism was observed in A (n = 2), B (n = 6) and C (n = 4). Thyroid enlargement was reported in A (n = 3) and B (n = 6). After 24 months, 10 patients developed hypothyroidism (four in A, three in B and three in C). TV reduction was similar between A and B (37.2 ± 25.5% vs. 39.3 ± 27.9%, p = 0.88), but different from the non-significant reduction in C (15.3 ± 28.3%, p = 0.08). Conclusions: Followed by 1.11 GBq, a very low dose of 0.005 mg rhTSH was equally safe and effective as 0.1 mg rhTSH. Both doses increased the efficacy of radioiodine. Adverse events were mild, transient and readily treatable.