Elevated Undercarboxylated and Reduced Carboxylated Osteocalcin are Associated with Metabolic Syndrome in Middle Age Asian Females

Abstract

Accumulating data suggest that bone plays a role in energy metabolism through decarboxylation of osteocalcin. Thus, we aimed to study the association of circulating under--carboxylated osteocalcin (UC-OCN) and car-boxylated osteocalcin (C-OCN) with metabolic syndrome in middle aged Asian population.In this cross-sectional study, 131 middle aged Asian subjects were recruited. Circulating UC-OCN, C-OCN and parameters of metabolic phenotype were measured.Circulating UC-OCN was increased in subjects with metabolic syndrome (8.1±7.2 ng/ml vs. 5.9±4.6 ng/ml, p=0.036). In contrast, C-OCN showed a non-significant trend towards reduction in subjects with metabolic syndrome (3.6±2.2 ng/ml vs. 4.3±1.8 ng/ml, p=0.057). Further analysis revealed that changes in both UC-OCN and C-OCN occurred primarily among females with metabolic syndrome. Interestingly, neither forms of OCN differed significantly between individuals with and without metabolic syndrome in males. Logistic regression revealed that UC-OCN was independently associated with metabolic syndrome after adjusting for multiple covariates. However, association between metabolic syndrome and C-OCN was dependent on gender (i. e., amongst females only) in the fully adjusted regression model.Variation in OCN (including its sub-species) was associated with variation in metabolic parameters amongst Asian adults. Circulating UC-OCN was increased while C-OCN was decreased in treatment-naïve females with metabolic syndrome. Our preliminary observations further supported a potential link between bone and energy metabolism in humans.