Vitamin D and metabolic/endocrinological levels among women with polycystic ovary syndrome: a Meta-analysis

Objective To assess the relationship between serum vitamin D level and metabolic/endocrine disorders in women with polycystic ovary syndrome (PCOS). Methods The clinical studies about vitamin D and PCOS were undertaken through popular English and Chinese databases until May 2017. Two authors independently screened studies, extracted data and evaluated study quality. Data analyses were conducted by RevMan5.3. Results Thirty studies were included. Meta-analysis showed vitamin D level of PCOS women was lower (SMD=-1.16, 95% CI=-1.84--0.49, I2=98%); Negative correlations between vitamin D and body mass index (BMI), fasting plasma glucose, fasting insulin, homeostatic model assessment-insulin resistance, homeostatic model assessment-beta cell function, free androgen index, parathyroid hormone were found. Positive correlations between vitamin D and high-density lipoprotein, sex hormone binding globulin were found. Compared with placebo, vitamin D could improve serum calcium level (SMD=0.81, 95% CI=0.40-1.22, I2=0%) and vitamin D level (SMD=2.79, 95% CI=2.02-3.55, I2=46%) but not other metabolic and endocrinological parameters. Conclusion Vitamin D level in women with PCOS is much lower. Vitamin D level is related to metabolic and endocrinological parameters among PCOS women. Vitamin D is not an effective treatment to improve metabolic and endocrinological levels among PCOS women. Key words: Vitamin D; Polycystic ovary syndrome (PCOS); Endocrinological and metabolic disorder; Meta analysis