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

Abstract

The data on the bone mineral density (BMD) and bone turnover markers (BTMs) in Indian adolescents are limited. 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. 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). 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. 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). 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.