Association between serum copeptin levels and non-obese normoglycemic polycystic ovary syndrome: A case control study.

Objective: Copeptin is a glycopeptide that increases under stress and is present in polycystic ovary syndrome (PCOS) patients with metabolic system disorders. We examined the relationship between copeptin and reproductive function in patients with normoglycemic PCOS with anovulatory cycles and normal weight. Materials and Methods: Women with unexplained infertility (n=52) and women with PCOS (n=57) were included in the study. PCOS was determined using the Rotterdam criteria. Biochemical tests including estradiol, follicle-stimulating hormone, luteinizing hormone, anti-Müllerian hormone (AMH), insulin, and copeptin were performed. Serum copeptin concentrations were measured using enzyme immunoassay. Results: There were no significant differences in demographic data, insulin levels, and insulin resistance between the PCOS and healthy volunteers. Copeptin levels were lower in the PCOS group (p<0.001). A significant negative correlation was observed between AMH and copeptin in the control group (r=-0.402, p= 0.013). In the PCOS group, a negative correlation was observed between antral follicle count and copeptin, as well as between AMH and copeptin (r=-0.544, p<0.01). Receiver operating characteristic (ROC) curve analysis was performed to determine the predictive value of copeptin levels. The estimated areas under the ROC curves for serum concentration were found to be statistically significant (p<0.001) with a cut-off value of 2.78 (95% confidence interval 0.701-0.896), sensitivity of 0.87, and specificity of 0.70. Conclusion: This study showed that copeptin levels are lower in patients with PCOS in the absence of insulin resistance and obesity than in healthy volunteers, and there is a negative correlation between copeptin and reproductive markers.