Use of low-dose radioiodine ablation for Graves' orbitopathy: results of a pilot, perspective study in a small series of patients

Objective: Elimination of thyroid antigens by total thyroid ablation (TTA), namely, thyroidectomy followed by radioiodine, may be beneficial for Graves' Orbitopathy (GO). TTA is usually performed with a 131I dose of 30 mCi. In Italy, this dose must be followed by a 24-h protected hospitalization, with increase in the waiting lists. In contrast, a 15 mCi dose can be given without hospitalization and with lower costs. Here, we investigated whether a lower dose of radioiodine can be used to ablate thyroid remnants in patients with GO, after thyroidectomy. Methods: The study was performed in two small groups of consecutive thyroidectomized patients (six patients per group) with Graves’ hyperthyroidism and GO. Patients underwent ablation with either 15 or 30 mCi of 131I following treatment with recombinant human TSH (rhTSH). The primary outcome was rhTSH-stimulated serum thyroglobulin (Tg) at 6 months. The secondary outcome was baseline Tg at 6 months. Results: Baseline Tg and rhTSH-stimulated Tg after at 6 months did not differ between two groups, suggesting a similar extent of ablation. rhTSH-stimulated Tg was reduced significantly compared with rhTSH-stimulated Tg at ablation in both groups. GO outcome following treatment with intravenous glucocorticoids did not differ between the two groups. Conclusions: Our findings may provide a preliminary basis for the use of a 15 mCi dose of radioiodine upon rhTSH stimulation in thyroidectomized patients with Graves’ hyperthyroidism and GO.