Vitamin D status in polycystic ovary syndrome

Background
Vitamin D deficiency (VDD) is an important public health problem worldwide, and polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age, with prevalence up to 10%. It is characterized by ovulatory dysfunction, resulting in oligomenorrhea and/or anovulation, hyperandrogenism, and polycystic ovarian morphology by ultrasound. Metabolic disturbances are present in most women with PCOS, including impaired glucose tolerance and insulin resistance (IR) with compensatory hyperinsulinemia. It may also create health risks such as T2DM, endometrial cancer, and cardiovascular disease. Accumulating evidence from several studies suggests that VDD may be involved in the pathogenesis of PCOS as the possible missing link between IR and PCOS. The aim of this study was to evaluate the suggested role of vitamin D in PCOS.
Participants and methods
The study included 70 women in reproductive age (16–44 years old) divided into two groups: group I included 50 women in reproductive age with PCOS, and group II included 20 healthy women in reproductive age with regular menstrual cycles. All were subjected to history taking; clinical examination, including blood pressure measurement; anthropometric measurements, such as body weight, height, and calculation of BMI, and waist and hip circumference with calculation of the waist/hip ratio; skin examination for acanthosis nigricans (sign of IR) and signs of androgen excess, such as hirsutism, androgenic alopecia, and acne; laboratory investigations, such as fasting blood glucose, lipid profile (total cholesterol, serum triglycerides, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol), serum levels of ionized calcium, serum levels of 25 (OH) vitamin D3, serum insulin level with calculation of Homeostatic Model Assessment of Insulin Resistance, serum luteinizing hormone, serum follicle-stimulating hormone with calculation of luteinizing hormone/follicle-stimulating hormone ratio, serum prolactin, serum total testosterone, and sex hormone-binding globulin with calculation of free androgen index; and imaging studies, such as pelvic ultrasonography with a 3.5 MHz convex electronic probe to examine the ovaries or transvaginal ultrasound.
Results
Serum 25 OH vitamin D level was statistically significantly lower in group I (women with PCOS) than group II (the control group) (mean: 6.05±2.56 vs 21.58±1.92 ng/ml) (< 0.001). There was a statistically significant positive correlation between serum 25 (OH) vitamin D level and serum ionized calcium (0.465, 0.001) and sex hormone-binding globulin (0.407, 0.003). However, there was a statistically significant negative correlation between serum 25 (OH) vitamin D level and BMI (=−0.363, 0.010), waist/hip ratio (=−0.255, =0.049), serum fasting insulin level (r=-0.487, <0.001), Homeostatic Model Assessment of Insulin Resistance (=−0.521, <0.001), serum total testosterone (=−0.418, 0.003), free androgen index (=−0.597, <0.001), right ovarian volume (=−0.44, 0.001), left ovarian volume(r=-0.407, 0.003), total ovarian volume (=−0.447, 0.001), right ovarian follicular number (=−0.445, 0.001), left ovarian follicular number (=−0.488, < 0.001), and total ovarian follicular number (=−0.474, 0.001).
Conclusion
VDD is very common in women with PCOS and is associated with metabolic derangement, including IR, cardiovascular risk factors, as well as ovulatory dysfunction, infertility, and hirsutism.