Thyroid eye disease in the context of autoimmune polyglandular syndromes: comparative clinical insights from a retrospective study.

Objectives: Thyroid Eye Disease (TED) may occur in patients with Graves' disease (GD) either as an isolated condition (iGD) or in the context of autoimmune polyglandular syndromes (aGD). Whether the presence of associated autoimmune diseases influences the severity of TED remains controversial. This study aimed to evaluate the prevalence of autoimmune-associated Graves' disease (aGD) among patients with moderate-to-severe, active TED requiring high-dose intravenous steroid therapy (IVS), and to characterize the associated autoimmune conditions. Methods: We conducted a retrospective multicenter study including GD patients treated with IVS for moderate-to-severe, active TED at two Italian tertiary referral centers. Patients were classified as having iGD or aGD based on the presence of concomitant autoimmune diseases. Demographic data, smoking status, thyroid parameters, steroid dose, and response to therapy were collected. Results: A total of 159 patients were included (mean age 51.7 ± 13.6 years; 27% males). Twelve patients (7.5%) had aGD, while 147 (92.5%) had iGD. Type 1 diabetes mellitus and rheumatoid arthritis were the most frequent associated autoimmune conditions. All aGD patients were female. No significant differences were observed between aGD and iGD patients in age, smoking status, cumulative steroid dose, or response to intravenous glucocorticoid therapy. Conclusions: Associated autoimmune diseases are uncommon among GD patients with moderate-to-severe TED requiring intravenous glucocorticoids. The possible role of poly-autoimmunity in the pathogenesis and progression of severe TED warrants confirmation in larger prospective studies.