Screening of organ-specific autoantibodies in a large cohort of patients with autoimmune thyroid diseases.

Background Autoimmune diseases tend to cluster in the same individual or in families. Four types of Autoimmune Polyglandular Syndromes (APS) have been described based on the combination of endocrine and/or non-endocrine autoimmune diseases. In particular, type-3 APS is defined by the association of an autoimmune thyroid disease (ATD) and other autoimmune diseases and has a multifactorial etiology. The natural history of autoimmune diseases is characterized by three stages: potential, subclinical and clinical. Methods To determine the prevalence of organ-specific autoantibodies [anti-adrenal (ACA), anti-ovary (StCA), anti-pituitary (APA), anti-parietal cells (PCA), anti-transglutaminase (tTGAb), anti-mithocondrial (AMA) anti-glutamic acid decarboxylase (GADA), anti-nicotinic acetylcholine receptor (ARAb)] in patients with ATD and to define the stage of the disease in patients with positive autoantibodies. From January 2016 to November 2018, 1502 patients [1302 F/200 M; 52.7±14.7 (m±SD) years, range 18-86] with ATD [1285/1502 (85.6%) with chronic autoimmune thyroiditis and 217/1502 (14.4%) with Graves disease] were prospectively enrolled. Results The most common organ-specific autoantibodies were PCA (6.99%) and GADA (2.83%) while the prevalence of the remaining autoantibodies was ≤1%. All autoimmune diseases, but celiac disease, were predominantly at the potential stage. Sex, ATD type, smoking habit and coexistence of other autoimmune diseases correlated with the susceptibility to develop chronic atrophic gastritis or autoimmune diabetes mellitus. Conclusions The association between ATD and chronic atrophic gastritis was the most common manifestation of type-3 APS, mainly at the potential stage, allowing to set an appropriate follow-up for early detection and timely treatment of the disease.