Association of serum midkine levels with insulin resistance and obesity in patients with polycystic ovarian syndrome

Objectives: Polycystic ovarian syndrome (PCOS) is thought to be a subclinical inflammatory state with increased levels of circulating pro-inflammatory cytokines. Midkine is a pleiotropic heparin-binding neurotrophic factor with pro-inflammatory properties, and growing evidence has shown a substantial effect of midkine in inflammation. This study aimed to test whether midkine has a role in PCOS development and its relation to obesity and insulin resistance (IR). Materials and Methods: In this comparative cross-sectional study, 56 women with PCOS and 36 eumenorrheic nonhirsute, age- and body mass index (BMI)-matched women as the control group were recruited. Routine and specific (midkine) laboratory analysis and IR measurements were applied to both the study groups. Results: There were no statistically significant difference between PCOS patients and controls with regard to serum midkine levels (P = 0.412). PCOS patients were further divided into two subgroups according to BMI levels. Serum midkine levels were found to be increased in overweight PCOS patients compared with normal-weight PCOS patients (P = 0.044). Although an increasing trend was observed in respect to serum midkine levels in PCOS women with IR (Homeostatic Model Assessment-IR ≥2.5), this elevation was not statistically significant (P = 0.301). Conclusions: The positive effect of obesity on midkine levels supports the idea that midkine is probably released from adipocyte cells. IR possibly has an important role in this mechanism.