Bone Abstracts

Objective: To determine the relationship between maternal and child bone density in a cohort of mothers and their children with and without rickets.

Methods: Using a case-control design without matching, areal forearm bone mineral density (aBMD) was measured in 52 and 135 Nigerian children with and without rickets, respectively, and their mothers. The metaphyseal site was located at the site of minimal bone density of the distal radius and ulna. The diaphyseal site was located at 1/3 the distance from the wrist to the elbow. Active rickets was confirmed or excluded in all children radiographically. We performed multivariate linear regression analyses to assess the relationship between maternal and child aBMD z-scores and to assess if nutritional rickets modified this relationship.

Results: Mothers of children with rickets had an earlier age of menarche (14.5±1.4 vs 15.1±3.0 years, P=0.05), were taller (161.3±5.5 vs 159.2±6.3 cm, P=0.04), and had a shorter duration of breast feeding (16.3±6.5 vs 19.0±3.1 months, P<0.001) than mothers of children without rickets. Children with rickets were younger (3.3±1.9 vs 5.2±2.4 years, P<0.001) and more likely male (57.0% vs 42.3%, P=0.04) than children without rickets. In a regression analysis adjusted for the presence of rickets in the child, child’s age and sex, height-for-age z-score, weight-for-age z-score, child forearm aBMD z-scores were associated with maternal z-scores at both metaphyseal (effect estimate 0.23 (95% CI 0.08 to 0.37)) and diaphyseal (effect estimate 0.16 (0.01 to 0.30)) sites of the forearm. In the adjusted model, the presence of rickets was inversely associated with child’s aBMD z-score at the diaphyseal site (effect estimate −0.45 (−0.65 to −0.24)) but not at the metaphyseal site. The positive relationship of maternal aBMD z-score with the child’s aBMD z-score was marginally greater in children with rickets (r=0.46) than in those without rickets (r=0.20) at the diaphyseal site (P=0.06 for interaction) but not at the metaphyseal site (P=0.48).

Conclusion: In Nigerian children with and without rickets, forearm aBMD z-scores were positively associated with maternal z-scores at metaphyseal and diaphyseal sites. Rickets in the child marginally modified the relationship at the diaphyseal site only.

Disclosure: Dr. Thacher is a consultant for Biomedical Systems, Inc.