The goal of the study is to explore the changes of vitamin D, hormonal indices, fat, and carbohydrate metabolism in the blood of women with polycystic ovary syndrome (PCOS), as well as to define the appropriateness of prescribing cholecalciferol in the complex treatment of this pathology. To achieve this goal, we have examined 80 women, aged 1835 years, with PCOS and underlying overweight and obesity, who were divided into four phenotype groups, according to the consensus of the PCOS Workshop Group in Amsterdam (2011). All women underwent a general medical examination, having measured their anthropometric parameters, body mass index (BMI) and clinical manifestations of hyperandrogenemia. Their serum was checked for the content of 25-hydroxyvitamin D (25(OH)D) , LH, FSH, progesterone, estradiol, androstenedione, dehydroepiandrosterone sulfate, 17-hydroxyprogesterone, anti-Müllerian hormone, insulin, and leptin. The study results found a decrease in vitamin D in the blood of women with PCOS in all clinical phenotypes, which lowered with the progression of obesity. Cholecalciferol
deficiency was associated with insulin resistance, hyperinsulinemia and hyperleptinemia. The correlation between the vitamin D content and hormonal indices in women with PCOS showed an inverse correlation between 25(OH)D and AMH levels, positive between insulin and 25(OH)D, and negative between vitamin D level and hirsutism score. Prescription of vitamin D in the complex treatment of women with PCOS leads to stabilization of hormones, decrease of HA signs, normalization of the menstrual cycle and restored ovulation.