INFLUENCE OF VITAMIN D ON THE COURSE OF ENDOCRINE DISEASES (literature review)

Abstract

Vitamin D is a prohormone that performs an important role in the body, namely: regulation of calcium and phosphorus levels, participates in the functioning of the bone system, regulation of the work of the endocrine and immune systems. This review article shows the influence of vitamin D on the functioning and course of thyroid diseases, the regulatory effect of vitamin D deficiency on the occurrence and progression of obesity, and the role of vitamin D deficiency in the course of polycystic ovary syndrome (PCOS). The authors used database PubMed and Google Scholar to find literature data. The probable mechanisms of the beneficial effect of vitamin D on the reduction of antithyroid antibody titers and the normalization of TSH levels in autoimmune thyroid diseases are highlighted. The effect of vitamin D preparations on restoring the levels of free T3 and T4 when used simultaneously with antithyroid drugs in Graves' disease (CG) has been demonstrated. The effect of this vitamin on the immune system due to a decrease in the production of pro-inflammatory cytokines (IL-2, IL-5, IL-17, TNF-α) has also been noticed. The expediency of screening obese patients for vitamin D deficiency and its use to block adipogenesis, counteract hyperleptinemia, and reduce insulin resistance is noted. The existence of a relationship between the appointment of vitamin D during IVF in women with PCOS with the frequency of implantation and the onset of pregnancy was analyzed. The importance of an optimal level of vitamin D for improving the receptivity of the endometrium and improving insulin sensitivity in women with PCOS is emphasized. It is worth noting the improvement of the probability of ovulation after its induction in women with PCOS with a sufficient level of 25-(OH)D in the blood. Women with PCOS and hirsutism have lower vitamin D levels than women without hirsutism, it can be hypothesized that there is a correlation between vitamin D deficiency and hyperandrogenism. Randomized, placebo-controlled, double-blind clinical trials are promising to further investigate the mechanisms of vitamin D exposure and determine the adequate dose for patients with obesity and its concomitant conditions, autoimmune thyroid diseases, and PCOS.