Endocrine Abstracts

Background: Increased rates of autoimmune diseases (ADs) have been reported in association with Hashimoto′s thyroiditis (HT); however, the risk factors for coexisting ADs in HT patients have been poorly investigated.

Objective: To evaluate the prevalence and factors associated with AD comorbidities in patients with HT.

Materials and Methods: We recruited 687 patients (626 F and 61 M, mean age at diagnosis 39 ± 14.06 yr, F: M=10.2: 1) diagnosed with HT in 2019-2021. Clinical, biochemical and demographic data of subjects with and without concomitant ADs were statistically compared.

Results: Among the 687 patients with TH, comorbid ADs were found in 322 (47%; n=292 F, mean age 39.5±14.8 yr), of whom 86 (12.5%) suffered from more than one associated ADs. Rheumatic diseases exhibited the highest frequency (n=226, 33%, including in order of frequency fibromyalgia, rheumatoid arthritis, Siogren syndrome, to mention a few,), followed by cutaneous (n=71, 10%, including vitiligo, psoriasis, alopecia, ….) and gastroenteric (n=62, 9% coeliac disease, atrophic gastritis, IBD, …) disorders. HT patients with and without comorbidities did not differ in gender and age at diagnosis (P> 0.005). However, stratifying patients by age, the prevalence of comorbidities increased with increasing age. The two groups did not differ regarding exposure to the main environmental factors (including cigarette smoking, residence in urban areas or with high industrial density compared to small towns/countryside, eating habits, iodine nutrition and vitamin D). However, a family history of either thyroid or non-thyroid autoimmune diseases was significantly more frequent (P<0.0001) in patients with associated comorbidities than in those without. Logistic regression analyses revealed that female sex (odds ratio [OR]=2.45, 95% confidence interval [CI]=1.24-4.82; P=0.011), age (OR=1.61, 95% CI=1.18-4.27; P=0.04) and family history of ADs (OR=5.18, IC 95%=2.217–12.105; P=0.001) were predictors of associated ADs.

Conclsions: Female HT patients with increasing age and a family history of ADs have increased rates of AD comorbidities. These data suggest a preponderant role of genetic background, of which familiarity can be considered a surrogate marker, in determining the risk of developing autoimmune comorbidities in HT patients.