Changes in DXA and quantitative CT measures of musculoskeletal outcomes following pediatric renal transplantation.

ABSTRACT

This prospective study evaluated changes in dual energy X-ray absorptiometry (DXA) whole body bone mineral content (WB-BMC) and spine areal bone mineral density (spine-BMD), and tibia quantitative computed tomography (QCT) trabecular and cortical volumetric BMD and cortical area in 56 children over 12 months following renal transplantation. At transplant, spine-BMD Z-scores were greater in younger recipients (<13 years), versus 898 reference participants (p < 0.001). In multivariate models, greater decreases in spine-BMD Z-scores were associated with greater glucocorticoid dose (p < 0.001) and declines in parathyroid hormone levels (p = 0.008). Changes in DXA spine-BMD and QCT trabecular BMD were correlated (r = 0.47, p < 0.01). At 12 months, spine-BMD Z-scores remained elevated in younger recipients, but did not differ in older recipients (≥ 13) and reference participants. Baseline WB-BMC Z-scores were significantly lower than reference participants (p = 0.02). Greater glucocorticoid doses were associated with declines in WB-BMC Z-scores (p < 0.001) while greater linear growth was associated with gains in WB-BMC Z-scores (p = 0.01). Changes in WB-BMC Z-scores were associated with changes in tibia cortical area Z-scores (r = 0.52, p < 0.001), but not changes in cortical BMD Z-scores. Despite resolution of muscle deficits, WB-BMC Z-scores at 12 months remained significantly reduced. These data suggest that spine and WB DXA provides insight into trabecular and cortical outcomes following pediatric renal transplantation.