Bone Abstracts

Objectives: Vitamin D is essential for bone modeling/remodeling but the relationship between vitamin D status, bone mineral density (BMD) and bone quality parameters remains controversial especially in adolescent population. The aims of this study wase to evaluate the vitamin D status and its correlation with BMD and bone quality parameters among adolescent girls in Hong Kong where information is lacking.

Methods: 156 adolescent girls (11–15 years old) were recruited separately in both summer and winter. Serum 25(OH) VitD was measured by liquid chromatography–tandem mass-spectrometry. BMD of bilateral femoral necks and bone quality parameters (bone morphometry, compartmental volumetric BMD (vBMD), and trabecular micro-architecture) of the non-dominant distal radius were measured by dual-energy X-ray absorptiometry and high-resolution peripheral quantitative computed tomography respectively. Multivariate linear regression was used to detect any correlation between bone parameters and serum 25(OH)VitD levels and P<0.05 was considered statistically significant.

Results: Prevalence of significant vitamin D insufficiency (25≤25(OH)VitD <50 nmol/l) and deficiency (25(OH)VitD <25 nmol/l) was 69.2 and 11.5% respectively. The mean serum 25(OH)VitD level in summer and winter were 43.9±12.0 and 34.9±10.0 nmol/l respectively. After adjustment for age, BMI, Tanner staging, physical activity level, dietary calcium intake and season, the positive correlations between 25(OH)VitD and femoral BMD was statistically significant. The positive correlations between 25(OH)VitD and femoral BMD, distal radius trabecular vBMD, meta-trabecular vBMD and bone volume-over-tissue volume remained significant for those with 25(OH)VitD level >25 nmol/l in summer. In contrast, no significant correlation was detected with the winter data.

Conclusion: Despite being a subtropical city located at a latitude of 22°N, vitamin D insufficiency with associated low femoral BMD and abnormal key bone quality parameters was found to be highly prevalent among adolescent girls in Hong Kong. This could post an important bone health issue of significant public health concern. Further studies to investigate the association with lifestyle factors and related therapeutic measures targeted on vitamin D insufficiency are warranted.

Funding: The project was funded by General Research Fund, University Grants Council of Hong Kong (project numbers: 468411, 468809).