Original Research Article DOI: 10.18231/2394-6377.2016.0024 International Journal of Clinical Biochemistry and Research 2016;3(4):453-460 453 Serum osteocalcin levels in metabolic syndrome Ayesha Almas 1 , Vanitha Gowda MN 2,* 1 PG Student & Tutor, 2 Associate Professor, Dept. of Biochemistry, MS Ramaiah Medical College & Hospital, Bengaluru, Karnataka *Corresponding Author: Email: vanithasukesh@hotmail.com Abstract Introduction: Osteocalcin has recently been proposed to play an important role in modulating glucose, lipid and energy metabolism. This study was undertaken to determine serum osteocalcin levels in metabolic syndrome and to study its association with measures of insulin resistance and cardiovascular risk factors. Methods: The study included 45 cases diagnosed as having metabolic syndrome defined by NCEP ATPIII criteria and 45 normal healthy subjects as controls. A fasting serum sample was collected from each subject and assayed for Fasting Blood Sugar, Lipid Profile, Insulin and Osteocalcin. Body Mass index (BMI), Waist hip ratio (WHR) and Homeostatic model assessment (HOMA) were calculated. Results: The mean serum Osteocalcin (ng/mL) levels were 4.56±1.75 and 10.302±1.96 in cases and controls respectively (p<0.001). In cases, Hyperglycemia and Hypertriglyceridemia were the most prevalent risk factors. The cases had a statistically significant negative correlation between osteocalcin and BMIand Triglyceride and a statistically significant positive correlation between osteocalcin and High Density Lipoprotein (HDL)(r = +0.964, p< 0.001). Metabolic syndrome subjects had lower serum osteocalcin levels. Greater the number of risk factors present, the lower was the osteocalcin level. The strongest positive association was found between osteocalcin and HDL. Osteocalcin was negatively associated with HOMA, FBS, BMI and triglyceride. Conclusions: These findings suggest that osteocalcin may have an essential role in modulating glucose and energy metabolism and in the pathophysiology of metabolic syndrome. Further studies may determine the utility of osteocalcin for cardiovascular risk prediction and strategies to increase osteocalcin levels, thus efficiently optimizing glucose, lipid and energy utilization. Keywords: Osteocalcin; Metabolic syndrome; Body Mass Index; HOMA; Insulin resistance Introduction Osteocalcin, a 49 amino acid non-collagenous protein produced by osteoblasts of the bone and stored in the hydroxyapatite matrix, is found in low concentrations in the circulation. Osteocalcin promotes osteoblastic differentiation, osteocyte maturation resulting in increased bone mineral density and bone formation rate [1] . A large number of studies have highlighted the role of osteocalcin as a hormone, on energy metabolism and cardiovascular system [2-6] . Animal and human studies have shown that serum osteocalcin levels are inversely associated with blood glucose level and body fat mass, directly correlated with insulin secretion, improved insulin sensitivity and adiponectin levels [2-6] . Low serum osteocalcin level has also been linked atherosclerosis and adverse cardiovascular changes like increased carotid intima-media thickness, coronary and carotid atherosclerosis [4] . Metabolic Syndrome is the clustering of interrelated modifiable cardiovascular risk factors that includes central adiposity, hypertension, hyperglycemia, hypertriglyceridemia with low high density lipoprotein cholesterol levels, hypercoagulability, insulin resistance and inflammation. Metabolic syndrome is strongly predicts the long term risk of diabetes and atherosclerotic cardiovascular disease [7] . Increasing prevalence of metabolic syndrome can be attributed to changes in nutrition, lifestyle and socioeconomic status, rural-to-urban migration, increasing obesity and sedentary lifestyles [7] . Prevalence of metabolic syndrome in an Indian population was 33.5% (24.9% in males, 43.2% in females), according to a study conducted in urban Orissa on 1178 subjects and 22.3% (25% in males and 22% in females) in an adult population in rural Karnataka [8,9] . According to the updated present AHA/NHLBI statement (Modified NCEP ATPIII criteria), presence of any three of the following five modifiable cardiovascular risk factors would make a clinical diagnosis of metabolic syndrome 1) Elevated waist circumference (WC) (with ethnicity specific values for South Asians) ≥90 cm in men and ≥80 cm in women, 2) Elevated serum triglycerides (TG) ≥150 mg/dL, 3) Reduced serum high density lipoprotein cholesterol(HDL)<40 mg/dL in men and <50 mg/dL in women, 4) Elevated blood pressure ≥130 mm Hg systolic blood pressure (SBP) and/or ≥85 mm Hg diastolic blood pressure (DBP) or on antihypertensive drug treatment in a patient with a history of hypertension, 5) Elevated fasting glucose (FBS) ≥100 mg/dL or on drug treatment for elevated glucose [10-12] . Studies exploring the association of serum osteocalcin levels and metabolic factors in normal