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 99mTc 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 cm3, P = <0.0001), mean thyrotropin receptor antibody level titer (19.02 vs. 13.37 IU/L, P < 0.0001), and 99mTc 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.
Keywords: GO; RAIT; TED; radioactive iodine therapy; thyroid eye disease; total thyroid ablation.
© 2023 by the Society of Nuclear Medicine and Molecular Imaging.