Serum total osteocalcin level as a vascular marker in elderly patients with metabolic syndrome

Abstract

Metabolic syndrome (MetS) is a major public health problem and a clinical challenge worldwide. Several epidemiological studies have confirmed the increased risk for cardiovascular diseases (CVD) in individuals with MetS. Total osteocalcin (TOC) is a bone-derived, noncollagenous protein that was recently recognized as a hormone-regulating energy metabolism factor. Importantly, osteocalcin expression has been described as having a role in calcifying vascular smooth muscle cells. We aimed in the present study to analyze the correlation between serum levels of TOC and vascular calcification in elderly persons with MetS. Seventy-four elderly men aged 65 years or older were included in the present study and divided into two groups. Group I comprised 40 patients who satisfied at least three criteria for MetS according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) definition, and group II comprised 34 age-matched healthy men who served as the control group. BMI was calculated, blood samples were taken for lipid profile analysis, and total osteocalcin (OCN) levels were evaluated using enzyme-linked immunosorbent assay kits. Carotid Doppler B mode ultrasonography was performed for all participants. Patients with MetS exhibited significantly higher BMIs, waist circumference, fasting blood sugar, triglycerides, blood pressure, total cholesterol, and lower high-density lipoprotein-cholesterol compared with controls. Patients with MetS had significantly lower levels of TOC compared with controls. Also, patients with MetS had significantly higher intima-media thickness and a higher number of carotid plaques compared with controls. TOC was significantly negatively correlated with parameters of carotid atherosclerosis. It is also negatively correlated with dyslipidemic parameters. Its correlation with components of MetS did not reach statistical significance. We concluded that serum osteocalcin levels were negatively correlated with carotid atherosclerosis in patients with MetS. This may reflect the role of osteocalcin as a circulating endocrine factor that regulates glucose metabolism and thereby cardiovascular risk in patients with MetS. Prospective studies are needed to assess the time course and relevance of serum osteocalcin in the development of atherosclerosis in patients with MetS.