In women with polycystic ovary syndrome (PCOS), especially those who are overweight, blood levels of the peptide kisspeptin, the hormone leptin, and the protein RBP4 are higher than in women without PCOS, and these markers are linked to metabolic problems.

To compare plasma kisspeptin, serum leptin, and serum retinol-binding protein 4 (RBP4) levels in women with and without polycystic ovary syndrome (PCOS) and to correlate these among each other and with clinical, hormonal, and metabolic parameters. Ninety women, including 54 women with PCOS and 36 without PCOS, participated in this study. For all patients, history and physical examinations were performed and blood samples were collected between days 3 and 8 of a spontaneous bleeding episode in the PCOS group and during normal menses of controls. Plasma kisspeptin, serum leptin, and serum RBP4 levels were measured using specific commercial assays. Kisspeptin, leptin, and RBP4 levels were significantly higher in the PCOS group than in controls. Kisspeptin and RBP4 levels were significantly higher among obese PCOS patients than controls. Leptin levels were higher among obese PCOS patients than non-obese PCOS patients or controls. Kisspeptin and leptin levels of PCOS patients were significantly correlated with RBP4 levels. When only obese PCOS patients were analyzed, kisspeptin levels correlated with only the free androgen index. These findings suggest that kisspeptin, leptin, and RBP4 are associated with metabolic disturbances in women with PCOS.