Differences in autoimmune thyroid diseases between females and males: the result of a complex interconnection of factors

Purpose: The aim of this paper is to review the scientific evidence for the link between autoimmune thyroid diseases (AITDs) and sex, and the plausible causes of the female prevalence in AITDs. Methods: An extensive literature search of published articles was conducted using online search engines. Results: AITDs are more frequent in the female sex. Numerous studies have focused on the differences between males and females in their presentation of AITD and their response to therapy, sometimes with conflicting results. Several factors are considered to be responsible for the higher incidence of AITDs in females, crucial among which is the relationship between sex hormones and the immune system. In addition to hormones, there is also evidence that sex chromosomes, epigenetic factors, foetal microchimerism, the microbiota and endocrine-disrupting chemicals (EDCs) play an important role in the predisposition of females to AITDs. Conclusion: The prevalence of AITDs in the female sex appears to be attributable to numerous factors, the most important being the influence of sex hormones on the immune system.