Insulin resistance is associated with increased circulating lipocalin-2 levels in polycystic ovary syndrome: a systematic review and meta-analysis.

Abstract

Introduction: This meta-analysis was conducted to compare the circulating lipocalin-2 levels in polycystic ovary syndrome (PCOS).

Evidence acquisition: Relevant studies were retrieved by online database and manual searching. The standardized mean differences (SMDs) with 95% confidence intervals (CIs) were obtained by a random-effects meta-analysis. The subgroup analysis based on the Body Mass Index (BMI) and the homeostasis model assessment-estimated insulin resistance (HOMA-IR) was conducted. Meta-analysis of correlations and meta-regression were performed for the associations of lipocalin-2 with the metabolic and hormonal covariates. The funnel plot analysis was used for publication bias.

Evidence synthesis: The combined effect size including a total of 13 studies showed no significant difference in lipocalin-2 levels between PCOS and control groups. However, the subgroup meta-analysis based on insulin resistance showed a significant difference in the circulatory lipocalin-2 levels in PCOS as compared to controls in both HOMA-IR<3 (SMD=-1.15, Z=2.42, P=0.02) and HOMA-IR>3 subgroups (SMD=0.91, Z=2.43, P=0.02).

Conclusions: There were significant associations of lipocalin-2 with age, BMI, estrogen and hyperandrogenism in PCOS. Lipocalin-2 level alterations in PCOS are associated to insulin resistance. More is the insulin resistance, higher is the lipocalin-2 level in PCOS as compared to controls.