Are plasma levels of visfatin and retinol-binding protein 4 (RBP4) associated with body mass, metabolic and hormonal disturbances in women with polycystic ovary syndrome?

OBJECTIVE: To analyze potential interactions of visfatin and retinol-binding protein 4 (RBP4) levels with body mass, metabolic, and hormonal status in normal weight and obese women with PCOS.

STUDY DESIGN: Body composition was determined by bioimpedance in 83 women (44 obese) diagnosed with PCOS and in 67 women (36 obese) without PCOS. In addition, serum glucose, lipids, androgens, FSH, LH, SHBG, insulin, visfatin, and RBP4 were measured in a fasting state and the free androgen index (FAI) was calculated, as was insulin resistance using the HOMA-IR assessment.

RESULTS: Plasma RBP4 levels were significantly higher in women of normal weight compared to obese subjects when both were diagnosed with PCOS (14.1 ± 4.6 vs.10.9 ± 4.5 ng/mL, p<0.001); while in non-PCOS subjects the opposite was found (10.8 ± 4.5 vs. 18.4 ± 11.6 ng/mL, p<0.01; respectively). Plasma visfatin levels were similar in PCOS and non-PCOS subjects. In non-PCOS subjects, positive correlations between RBP4 level and anthropometric parameters were observed. In PCOS, RBP4 levels inversely correlated with serum insulin levels and HOMA-IR values. No correlation was found between plasma visfatin levels and anthropometric parameters in all study groups. Similarly, no correlation was found in PCOS and non-PCOS subgroups. Additionally, there was an inverse correlation between RBP4 and LH concentrations and LH/FSH ratio in all study subjects.

CONCLUSIONS: Plasma visfatin level is not a useful biomarker of insulin resistance and hyperandrogenism. RBP4 level reflects visceral body fat content in non-PCOS women. Decreasing RBP4 release along with increasing insulin resistance and hormonal disturbances may be a compensatory mechanism preventing deterioration in obese PCOS.