Bone Abstracts

The high prevalence of renal osteodystrophy (ROD) in pediatric renal transplant recipients has been linked to the duration on dialysis pre transplant, exposure to steroids, nutritional deficiencies, limitations in physical activity and ethnicity. The incomplete resolution of ROD in transplant recipients has been found to be associated persistent abnormalities in mineral metabolism associated with allograft dysfunction in the post transplant period.

We hypothesized that the rate of change in bone mineral density is associated to the change in allograft function after correcting for the change expected with increasing age.

We retrospectively reviewed the DEXA scan and iothalamate GFR (iGFR) results in 48 post pubertal pediatric renal transplant recipients who had at least one study done between 2005 and 2012. These tests are standard of care in our program at 1 year post-transplant in children above 12. The mean age was 16±2.3 (12–20) years and 60% (29/48) were male. The average age at transplant was 13±4.2 (2–19) years and 62.5% (30/48) were transplanted preemptively. The duration of CKD prior to transplant was 904.6±829.6 (37–3856) days. 17/48 patients had more than one DEXA scan done. The mean Z-score for the spine, femur and hip were −0.2±1.3, −0.5±1.1, and −0.4±1.0. Spine, femur and total hip BMD Z-scores were >2 S.D. below the mean in 6.25, 8.33, and 6.25% respectively. Change in allograft function correlated inversely with change in Z-score at the hip (r²=−0.725; P value=0.027) but did not reach statistical significance for the spine (r²=−0.625; P=0.057).

Although the DEXA scan has limitations in the detection of impaired bone mineralization in the pediatric population, it appears to maintain a strong correlation with allograft function in this limited cohort.