Changes in DXA and Quantitative CT Measures of Musculoskeletal Outcomes Following Pediatric Renal Transplantation

Abstract

This prospective study evaluated changes in DXA whole body bone mineral content (WB-BMC) and spine areal bone mineral density (spine-BMD), and tibia quantitative CT (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), vs. 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, WBBMC Z-scores at 12 months remained significantly reduced. These data suggest spine and whole body DXA provide insight into trabecular and cortical outcomes following pediatric renal transplantation.

Skeletal outcomes by peripheral quantitative computed tomography and dual-energy X-ray absorptiometry in adolescent girls with anorexia nervosa

“…It has previously been demonstrated that this relationship occurs because cortical BMD varies in such a narrow range that BMC is almost entirely a function of bone size [18, 30]. Our data in AN are consistent with these previous reports.…”

“…However, these children had significantly lower mean pQCT trabecular vBMD Z-scores and significantly greater cortical vBMD Z-scores than the reference population [17]. Similar discrepancies between DXA and pQCT have been seen in studies of pediatric patients with Crohn disease and cystic fibrosis [18, 19]. …”

The evaluation of bone metabolism in children with renal transplantation

“… reported an elevated trabecular volumetric BMD (by peripheral quantitative computed tomography examination) in younger RTR and a significant decrease in association with greater glucocorticoid exposure. More recently, normal values of BMD z scores were obtained in children with RTx both at the time of transplantation and 12 months, however, with a significant decrease occurring over this period . Similarly, mean BMD z scores adjusted for HAZ showed better mineralization levels in our patients at the time of RTx and osteopenia was present in only 12% (n = 3).…”

A Piece of the Puzzle: The Bone Health Index of the BoneXpert Software Reflects Cortical Bone Mineral Density in Pediatric and Adolescent Patients

“…As children with suspected osteopathology are often also affected by chronic disease or endocrine disorders resulting in deviant growth, a further correction of the Z-score for the actual height of the patient is necessary[ 2 , 6 , 9 , 10 ].…”