Associations Between Serum Magnesium Concentrations and Polycystic Ovary Syndrome Status: a Systematic Review and Meta-analysis

Magnesium (Mg) is the second most frequent intracellular cation in humans with a critical role in insulin metabolism and glucoregulation. Women with polycystic ovary syndrome (PCOS) often present with insulin resistance and impaired glucoregulatory status; however, their Mg status remains unclear. Therefore, we aimed to conduct a systematic review and meta-analysis to evaluate serum Mg concentration in women with PCOS and compare it with that of controls without PCOS. Online databases of PubMed, Scopus, Cochrane Library, and ISI Web of Science were searched for studies evaluating the relationship between Mg concentrations and PCOS status until October 2019. Pooled weighted mean differences (WMDs) of serum Mg levels were calculated using random effects models. A total of eight studies (10 arms;n = 2026 women) were included. Pooled effect sizes, expressed as WMD and 95% CI, revealed decreased serum Mg concentrations in women with PCOS compared with controls (- 0.09 (- 0.17, - 0.02) mmol/L;P = 0.01). However, significant heterogeneity was detected across the studies (I-2 = 98.0%,P < 0.001). Despite the classification of studies based on baseline BMI classes, we did not detect the potential source of the observed heterogeneity. Subgroup analysis showed that overweight and obese women (BMI >= 25 kg/m(2), 0.07 mmol/L (- 0.14, - 0.01);P = 0.02) with PCOS had lower magnesium concentrations than normal women (BMI < 25 kg/m(2), - 0.11 (- 0.25, 0.04) mmol/L;P = 0.14) compared with the control group. Serum Mg concentrations appear to be declined in overweight or obese women with PCOS, which may warrant screening and management of Mg status in this clinical population. High-quality studies are needed to elucidate the relationship between Mg concentrations and the development of PCOS.