Bone mineral density in pediatric transplant recipients.

BACKGROUND: Reduced bone mass and fragility fractures are known complications after transplantation in adults. Far less is known about the skeletal effects of transplantation in children and adolescents. METHODS: This cross-sectional study examined the skeletal status of children (ages 9-18 years) who were at least 1 year post-cardiac (n=13), post-renal (n=8), or post-bone marrow (BMT; n=15) transplantation. Bone mass at total hip, femoral neck, spine (L2-4), and whole body (WB) was determined by dual energy x-ray absorptiometry and compared with age, sex, and ethnic-specific reference data. Standard deviations (z-scores) were calculated for both areal bone mineral density (BMD) and estimated volumetric bone density (bone mineral apparent density [BMAD]). RESULTS: Cardiac transplant patients had significantly lower BMD z-scores compared with the reference population at all skeletal sites. BMT recipients had significantly reduced BMD z-scores at total hip, spine, and WB. Kidney transplant patients had a significantly reduced WB BMD z-score only. Spine BMAD z-scores remained significantly reduced in cardiac and BMT subjects. Three of 36 patients had radiographic evidence of spinal fracture after transplantation. No correlation between steroid dosage and any measure of bone mass was observed. CONCLUSIONS: Cardiac and BMT recipients had reduced BMD at multiple skeletal sites, and renal transplant recipients had reduced WB BMD for age. Deficits in spine bone density persisted after correcting for small bone size using BMAD. Low bone density and the occurrence of vertebral fractures indicate that cardiac, renal, and bone marrow transplantation in children is associated with reduced bone health.

Low-dose intravenous pamidronate reduces fractures in childhood osteoporosis.

Despite the proven efficacy of low-dose pamidronate in adults with osteoporosis, the efficacy of the low-dose regimen in children has not been studied. Pamidronate (1 mg/kg) was administered intravenously once every 3 months to 11 children with osteoporosis. Treatment was associated with reduced fracture rates and increased areal (BMD) and volumetric (BMAD) bone mineral density measured by dual energy X-ray absorptiometry (DXA). The mean annualized percent gain was 20.1 +/- 16.9 (4.7 to 59.1, n = 9) for spinal BMD and 15.1 +/- 18.1 (-11.0 to 40.2, n = 9) for spinal BMAD. Common adverse effects including fever, muscle aches, nausea and fatigue were self-limited and generally occurred only after the first infusion. Clinically significant hypocalcemia did not occur. Low-dose pamidronate appears promising in the treatment of childhood osteoporosis.