Radioiodine Ablation of Thyroid Remnants in Patients with Graves' Orbitopathy.

Our purpose was to assess response after ablation of thyroid remnants (ATR) with radioactive iodine therapy in patients with unstable Graves' orbitopathy (GO) after subtotal thyroidectomy. Methods: Thirty patients with mild ( n = 4, 13%), moderate-to-severe ( n = 25, 83%), or very severe GO ( n = 1, 3%) were analyzed in this retrospective study. The primary endpoint was the improvement of GO-related symptoms as assessed by clinical activity scores, NOSPECS, and soft-tissue inflammation scores at 3 and 12 mo after ATR. Ablation success was defined by a decrease in ^99m Tc uptake on thyroid scintigraphy, remnant volume, and thyrotropin receptor antibody levels at 3 mo after ATR. Results: Twelve months after ATR, clinical activity scores, NOSPECS, and soft-tissue inflammation scores showed a significant decrease from 3.4 to 1.3 ( P < 0.0001), 5.9 to 4.9 ( P = 0.007), and 4.7 to 2.1 ( P = 0.0001), respectively. The GO was inactive in 27 of the 30 (90%) patients after 3 mo and in 29 (97%) after 12 mo. No new activation of GO occurred. Remnant volume (1.4 vs. 0.4 cm ³ , P = <0.0001), mean thyrotropin receptor antibody level titer (19.02 vs. 13.37 IU/L, P < 0.0001), and ^99m Tc uptake (0.5% vs. 0.1%; n = 12; P = 0.04) decreased significantly until 3 mo after ATR. Discussion: Radioactive iodine therapy after thyroidectomy can successfully ablate residual thyroid remnants, leading to an improvement in GO, a reduction in inflammatory activity, and stabilization of thyroid function. Thus, scintigraphy should be considered for patients with unstable GO after thyroidectomy to rule out thyroid remnants.
(© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)