["It is unclear whether Hashimoto's thyroiditis and Graves' disease (often referred to as autoimmune thyroid disease, AITD) cluster to the same extent with other autoimmune disorders.", "We assessed adrenal, β-cell, celiac and gastric antibodies in a cohort of 523 adult patients with Graves' disease and 359 patients with Hashimoto's disease and compared their clustering.", "Adrenal autoimmunity associated more often with Hashimoto's disease (9.0%) than with Graves' disease (3.3%, P=0.001). β-cell autoimmunity was seen more frequently in Hashimoto's disease (25.4%) than in Graves' disease (15.6%, P=0.001) patients. We found low prevalences of celiac autoimmunity (1.2% for Graves' and 1.2% for Hashimoto's disease). Celiac and gastric autoimmunity were not statistically different in Hashimoto's and Graves' disease patients. Although gastric autoimmunity itself was equally prevalent (around 20%), Hashimoto's disease often showed significantly more clustering of adrenal autoimmunity with gastric autoimmunity (5.3%) than Graves' disease (1.2%, P=0.001). Similarly, clustering of adrenal autoimmunity was seen with β-cell autoimmunity in Hashimoto's patients (3.2%), while such clustering was much less encountered in 359 Graves' patients (0.9%, P=0.029)."] Does clustering of additional autoimmunity behave differently in Hashimoto 's patients compared with Graves ' patients?