Systematic studies on the association of autoimmune thyroiditis (AIT), as pivotal disease and nonendocrine autoimmune diseases (NEAD) are scarce and mostly based only on the presence of circulating autoantibodies. In a large cohort of consecutive outpatients, AIT was diagnosed in 1541 (28.2%) and whenever additional autoimmune disorders were suspected, they underwent further screening. Diagnostic criteria were according with the Consensus Conferences for each suspected autoimmune disease. The association AIT+NEAD was detected in 250/1541 (16.2%) patients (227 W and 23 M; W/M 10:1; median age=39 years). Of these, 64 patients (25.6%) had more than one autoimmune disease associated with AIT. The most frequent associated disease was chronic atrophic gastritis (CAG) (34.8%), followed by nonsegmental vitiligo (22.3%), celiac disease (11.0%), anti-phospholipids syndrome and multiple sclerosis (7.6%). Although most of patients with multiple autoimmune disorders were adult to old, 9.9% of them had a second autoimmune disease before the age of 30 years. In this group the most frequent diseases associated with thyroiditis were vitiligo (39%) and celiac disease (26%), while CAG was less observed (13%). Peculiar characteristics of patients with AIT+NEAD were thyroxine malabsorption, chronic unexplained anemia and recurrent pregnancy loss (RPL). Thyroxine malabsorption was indeed higher than in patients with isolated thyroid diseases (31 vs 12.3%; P<0.0001; OR=3.60). RPL was observed in 6.9% of patients with AIT+NEAD as compared with 1.7% found in patients with isolated thyroid diseases (P<0.0001; OR=4.06). Unexplained anemia was found in 2.2% of patients with isolated thyroid diseases and in 18.3% of patients with AIT+NEAD (P<0.0001; OR=8.23). In conclusion: i) 1 patient out of 6 has NEAD associated with AIT and 1/10 of them is younger than 30 years; ii) atrophic gastritis, vitiligo and celiac diseases are the most frequent autoimmune disorders associated with AIT, being their prevalence age-related; iii) the presence of thyroxine malabsorption, chronic unexplained anemia and recurrent pregnancy loss in patients with AIT should induce to look for other autoimmune diseases.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported, however funding details are unavailable.
05 - 09 May 2012
European Society of Endocrinology