006). This suggested stronger associations between lean adjusted total fat mass and trabecular density in the male than female children. In this pre-pubertal, free-living population, fat mass, adjusted for lean mass, was associated positively with bone size but negatively with true volumetric density assessed by pQCT, across the whole fat mass distribution. We recruited children from a free-living population cohort and used objective measures of body composition and bone size and density.

However, there are several limitations to our study. We were only able to study a proportion of the original cohort. However the children who underwent the 6 year assessment did not differ at birth or 1 year old from those who did not. Mothers of children who underwent 6 year assessment were broadly similar to mothers of those children who did not, but were more likely to be of higher social class and Tariquidar research buy less likely to smoke. However, as the analysis

is based on internal comparisons it is difficult to envisage how this would have spuriously find protocol shown an association between fat mass and bone size and density. The study population included a very small number of non-white Caucasian children and therefore it is uncertain whether our findings may be generalisable across these other ethnic groups. Secondly we used DXA to measure bone mass. This technique is associated with technical limitations in children. Measurement of bone mineral 5-Fluoracil in young children is

hampered by their tendency to move and also by their low absolute BMC. However, we used specific paediatric software, and movement artefact was modest and uniform across the cohort; those few children with excessive movement were excluded from the analysis. DXA measures of bone mass have been shown to correlate well with whole body calcium content in ashing studies of piglets [13] and [14]. Finally, we used a number of adjustments in the analyses, for example adjusting fat mass for lean mass. There is a biological rationale for this approach, as described in the methods, but as a result of co-linearity between measurements, it is possible that some analyses were over-adjusted; our conclusions are supported, however, by the results from the unadjusted analyses. Children who are overweight have approximately a twofold increased risk of forearm fractures compared with controls [15]. A recent study has shown that among obese children with a history of fracture, lumbar spine bone mineral apparent density was reduced by 2–3 sd compared with non-obese children with a history of fracture [16]. Thus at least part of the increased risk of fracture in obese children may be mediated via reduced bone density rather than other factors such as increased risk of falling. Our findings are in accord with some, but not all, studies of pre-pubertal children using DXA and pQCT.