The effect of growth hormone deficiency on size-corrected bone mineral measures in pre-pubertal children

Abstract

Growth hormone deficiency (GHD) in children has been frequently perceived to be a cause of low bone mass accrual. The confounding effects of poor growth limit the interpretation of prior studies of bone health in GHD. We studied size-corrected bone mineral measures in 30 pre-pubertal GHD children and 75 healthy controls. Our study shows that size-corrected whole-body bone mineral content of GHD children were comparable with controls. The purpose of this study is to evaluate the effects of GHD on size-corrected bone measures at the lumbar spine (LS) and the whole body (WB). LS bone area (BA), LS bone mineral content (BMC), WB BA, WB BMC, and lean body mass (LBM) were measured in 30 pre-pubertal GHD children and 75 controls by dual-energy X-ray absorptiometry. Multiple linear regressions were used to calculate size-corrected (Sc) LS BA(Sc), LS BMC(Sc), WB BA(Sc), and WB BMC(Sc) from control subjects using height and age as independent variables. Furthermore, the relationship between muscle and bone was studied by first assessing LBM for height (LBM(Ht)) and then determining WB BMC for LBM (WB BMC(LBM)). All values were converted to Z-scores and compared with the control. At diagnosis, WB BMC(Sc) Z-score of GHD children was not significantly different from controls. However, mean Z-scores of LS BA(Sc) (-0.89 ± 0.84, p < 0.0001), LS BMC(Sc) (-0.70 ± 1.1, p < 0.001), WB BA(Sc) (-0.65 ± 1.0, p < 0.006), and LBM(Ht) (-0.66 ± 1.7, p < 0.01) were significantly reduced, and WB BMC(Lbm) (0.78 ± 1.5, p < 0.003) was significantly higher in GHD children than controls. Size-corrected WB BMC of GHD children were comparable with controls, and bones were normally adapted for muscle mass. Determinants of bone strength which may primarily be affected by GHD are muscle mass, bone size, and geometry rather than bone mass.