Inverse association between serum osteocalcin and pericardial adipose tissue in Koreans: cross-sectional study

Background: Osteocalcin (OC), a bone matrix protein of osteoblastic origin, is thought to play a role in systemic metabolic function. However, the relationship between serum OC levels and pericardial adipose tissue (PAT) volume remains unclear. Methods: Using a cross-sectional design, 438 participants (88 females, 350 males) who underwent cardiac CT imaging were enrolled. Simple and partial correlation analyses were performed. OC levels were divided into tertile groups to assess their relationship with PAT, adjusting for age, sex, smoking, hypertension and type 2 diabetes. Linear and logistic regression models were also applied. Results: The mean participant age was 55.7 years. The average serum OC level was 15.9 ng/mL, and the mean PAT volume was 127.6 cm3. OC level and PAT volume showed an inverse correlation that was significant in both unadjusted (r=-0.158, P=0.001) and covariate-adjusted (r=-0.106, P=0.032) analyses. Inter-tertile PAT differences remained significant after stratification (P<0.05). In multivariate regression analysis, the inverse association remained statistically significant after adjustment for age, sex and smoking (P=0.019), but not after additional adjustment for body mass index (P=0.656). After adjustment, relative to the highest OC tertile, the odds ratios for being classified into the highest PAT tertile were 2.73 (95% confidence interval [CI], 1.43-5.21) for the lowest and 2.99 (95% CI, 1.59-5.66) for the middle OC tertile. Conclusion: Serum OC level was inversely associated with PAT volume; however, this association was attenuated after adjusting for adiposity-related variables, suggesting that shared metabolic or body composition factors may partly account for the observed relationship.