ESPE Abstracts

Background: Osteocalcin, a metabolic active hormone, correlates to bone formation and inversely to BMI and waist circumference in adults.

Objectives: To investigate whether osteocalcin in infancy and early childhood is related to childhood growth or body composition.

Methods: A Swedish longitudinal birth cohort of 551 children, gathered blood samples from birth until 5 years of age together with regular anthropometric measurements until 8 years of age. In addition, DXA-scans (Dual Energy X-ray Absorptiometry) were performed at 8 years of age for half of the population.

Results: During infancy, boys’ osteocalcin at 4 months of age correlated inversely to weight consecutively from 4 to 24 months of age and to waist circumference from 6 to 24 months of age, but for girls, correlations were only found for weight at 4 months and waist circumference at 6 and 18 months of age (ρ <.3, P = .001 to .048). In childhood, boys’ osteocalcin levels at 5 years of age correlated positively to height and weight at 5 and 6.5 years of age but not to later measurements, (ρ <.3, P <.01). While girls’ osteocalcin showed positive consecutive correlations at 3 years of age to all later weight and height measurements, (ρ <.3, P = .003 to .023). In infancy, boys’ osteocalcin was inversely correlated to Body Mass Index (BMI) at most ages until 2 years of age, while girls’ osteocalcin from the age of one, correlated to later BMI-measurements in a positive way. Using DXA-data, boys’ osteocalcin at 5 years of age correlated to Fat Free Mass Index (FFMI) (ρ .212, P = .026), but not to Fat Mass Index (FMI) (P = .515) at 8 years of age, the opposite was seen for girls’ osteocalcin at 3 years of age which correlated to FMI (ρ .222, P = .020) but not to FFMI (P = .128).

Conclusion: Osteocalcin showed inverse correlations to weight, height and body composition in infancy and positive correlations during childhood. Sex differences were present in infancy and childhood. Osteocalcin in childhood, correlates to later FMI for girls and to later FFMI for boys. All correlations were weak but consistent. This study contributes to the knowledge on human osteocalcin in relation to later growth and body composition and might guide further research on the topic to better understand of the biological functions of the hormone osteocalcin in the future.