Bone Mineral Density and Serum Bone Turnover Markers among Post-Menarchal Girls from Rural South India

BACKGROUND: The data on the bone mineral density (BMD) and bone turnover markers (BTMs) in Indian adolescents are limited. OBJECTIVES: To assess BMD at lumbar spine (LS, L1-L4) and femoral neck (FN) in South Indian post-menarchal girls and correlate it with dietary calcium intake (mg/day), physical activity score and post-menarchal years. The study also assessed serum BTMs and their correlation with chronological age in the study population. METHODS: This cross-sectional study included apparently healthy post-menarchal adolescent girls aged 12–16 years randomly selected from the community. Participants with vitamin D deficiency were excluded. The data on calcium intake and physical activity were obtained using validated questionnaires. All participants were evaluated with serum calcium, 25-hydroxy vitamin D, parathyroid hormone, N-terminal propeptide of type 1 collagen (P1NP) and Beta-CrossLaps (CTx) and BMD at LS and FN using dual X-ray absorptiometry (DXA). STATISTICAL ANALYSIS: EpiData version 3.1 was used for the data entry. The data analysis was done using Statistical Package for Social Sciences (SPSS) version 21. Continuous variables were expressed as mean ± SD. Pearson’s correlation coefficient (r) was calculated, and two-tailed Kendall’s tau-b test was used for assessing correlation of all nonparametric measures. RESULTS: A total of 103 participants were screened, and data from 77 were analysed. There was a significant positive correlation of BMD at LS with chronological age (r: +0.235, P = 0.036), but not at FN. Positive correlation of BMD with increase in post-menarchal years was also noted at LS (r: +0.276, P = 0.015). There was no significant association of BMD with calcium intake and physical activity scores at both sites. There was a significant negative correlation of serum BTMs with age CTx (r: -0.596, P = 0.0001) and P1NP (r: -0.505, P = 0.0001). CONCLUSION: This study provides insight into the reference BMD range at LS spine and FN in South Indian rural post-menarchal adolescent girls. BMD positively correlated, whereas BTMs negatively correlated with age. The study also provides the first Indian reference range for serum BTMs in this age group.