Introduction: Although adipose tissue largely plays a role in the etiopathogenesis of metabolic syndrome (MS), which is an inflammatory process, the skeleton may also contribute to this process through osteocalcin (OC), which is a bone-derived protein. In this study, we aimed to evaluate OC levels in postmenopausal women with MS and to investigate the association of OC levels with the metabolic and inflammatory parameters. Methods: Thirty-five postmenopausal women diagnosed with MS were recruited for the study. Sixteen postmenopausal women without any of the MS criteria formed the control group. Body weight, height, and waist and hip circumference of all of the subjects were measured and body mass indices (BMIs) were calculated. Levels of serum glucose, insulin, C-peptide, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, albumin, creatinine, calcium, phosphorus, total alkaline phosphatase, parathormone, and as inflammatory parameters, erythrocyte sedimentation rate, fibrinogen, and high-sensitive C-reactive protein (hsCRP) were studied from fasting venous blood samples of all the subjects. Homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. Serum total OC levels were studied from all of the subjects. Bone mineral densities were also measured. Results: Serum OC levels of the group with MS median (5.37 ng/mL) were lower than the OC levels of the group without MS (P < 0.01). Serum OC levels significantly and negatively correlated with fasting blood glucose (r = -0.310, P < 0.05), insulin (r = -0.343, P < 0.05), and HOMA-IR (r = -0.384, P < 0.01) values. Serum OC levels showed a significant and negative correlation with body weight (r = -0.293, P < 0.05), BMI (r = -0.333, P < 0.05), and waist-to-hip ratio (r = -0.384, P < 0.05). The inflammatory markers in the patient group were significantly higher than the control group. We found a negative association between serum OC levels and hsCRP levels in all cases (r = -0.283, P < 0.05). Conclusion: In the presence of MS, OC levels are significantly low and display a close association with glucose metabolism and adipose tissue. In addition, OC may play a regulatory role in subclinical systematic inflammatory response.
Keywords: inflammation; insulin resistance; metabolic syndrome; osteocalcin.