Serum concentrations of carboxylated osteocalcin are increased and associated with several components of the polycystic ovarian syndrome

Intriguing studies suggest that osteocalcin (OC) and its carboxylated (Gla)/uncarboxylated form are involved in the regulation of insulin secretion and action. Additionally, advanced glycated end products (AGEs) directly regulate the secretion of these osteoblast-derived molecules. In polycystic ovarian syndrome (PCOS), among the pathophysiological aberrations, deregulation of insulin secretion and action as well as elevated AGEs levels have been demonstrated. In this study, we evaluated the serum levels of osteocalcin and Gla osteocalcin and their possible associations with metabolic, hormonal, and ultrasonographic components of PSOS: 97 women were studied, 50 PCOS patients and 47 controls, matched for age and body mass index (BMI). In each subject, the levels of bone metabolism markers have been evaluated, and metabolic and hormonal profiles as well as ovarian ultrasound were carried out. Osteocalcin (4.30 +/- A 1.74 vs. 6.20 +/- A 1.78 ng/ml, P < 0.0005) values were significantly lower, whereas Gla osteocalcin (37.93 +/- A 6.87 vs. 9.64 +/- A 8.21 ng/ml, P < 0.0005) and receptor activator for nuclear factor-kappa B ligand (0.54 +/- A 0.26 vs. 0.16 +/- A 0.15 pmol/l, P < 0.0005) values were significantly higher in PCOS subjects compared to the control group, independently of obesity. A significant association was disclosed between osteocalcin and Gla osteocalcin with androgens, insulin resistance, AGEs, and ovarian morphology. Receiver operating curve analysis revealed that Gla osteocalcin [AUC, 0.975 (95% CI, 0.93-1.00)] as well as AGEs are significant prognostic factors of PCOS [AUC, 0.986 (95% CI, 0.97-1.00)]. Lower osteocalcin and elevated serum levels of its carboxylated form are displayed in PCOS subjects and are associated with several PCOS components. These findings suggest a potential interaction between bone-derived markers and the metabolic/hormonal abnormalities observed in PCOS. However, the pathophysiological mechanisms and moreover the possible clinical implications require further investigation.