Association between gut microbiota and thyroid dysfunction

The article is devoted to modern researches about the potential role of gut microbiota in the development of thyroid pathology. Gut microbiota plays a major role both in the formation and maintenance of human health and in the pathogenesis of a wide range of diseases. There is evidence of the relationship between the gut microbiota and the immune system, the risk of developing several malignant and autoimmune diseases. The article discusses the functions of the gut microbiota and the factors that determine its composition. Studies have shown a connection between the gut microbiota and the thyroid gland, which formed the basis for the formation of the theory of the gut-thyroid axis. It has been shown that the gut microbiota takes part in the metabolism of thyroid hormones and ensures their enterohepatic circulation. It is assumed that one of the links between the thyroid gland and gastrointestinal microorganisms is the immune system. The results of studies examining the taxonomic composition of the gut microbiota in patients with autoimmune thyroiditis and Graves’ disease are presented. It is hypothesized that the composition of the gut microbiota may influence the requirement for levothyroxine, especially in patients with subclinical hypothyroidism. On the other hand, levothyroxine, to a lesser extent, directly hypothyroidism as a result of autoimmune thyroiditis are associated with bacterial overgrowth syndrome despite the achievement of euthyroidism, and may affect the composition of the microbiota. Even though autoimmune thyroid diseases are quite common in the general population, little work has been done on this issue. More reliable basic and clinical researches are needed to identify specific relationships and mechanisms of development of thyroid pathology depending on changes in the composition of the gut microbiota, as well as to assess the potential for therapeutic use.