Decreased bone mineral density in the pediatric renal transplant population

All renal transplant recipients at our centre have had bone mineral density assessment (BMD) by DEXA scans of their lumbar spine while on the transplant waitlist and at 6-month intervals post-transplant over the past 7 yr. Risk factors for osteopenia and osteoporosis including donor source, dialysis status prior to transplantation, prior renal disease, and biopsy confirmed rejection events and their relationship to BMD of the lumbar spine were assessed. Thirty-nine children transplanted over the past 7 yr were included in this study. In total, 127 BMD longitudinal assessments were performed. From 1990 to 1997, ATG/ALG was used as antibody induction therapy. From 1997 to 2002, Basiliximab was utilized. Cyclosporin A (CyA) was the primary immunosuppressant for most children with tacrolimus as primary (n = 2) and switch for CyA failure or toxicity (n = 16). Prednisone was administered at a dose of 1 mg/kg/day for the first week and tapered to 10 mg/m2/alternate day by 1 month post-transplant. Azathioprine 1.5 mg/kg/day was continued for 1 yr and discontinued in children who were rejection free. All rejections were biopsy confirmed and treated with a prednisone pulse. Using a repeated measures regression analysis, we have found that L1-L4 BMD z score is affected by height and transplant number. It is also related to time relative to transplant in a quadratic fashion. There was an inverse relationship between advancing patient age and L1-L4 BMD z score. L1-L4 BMD z score was not related to weight, pre-existing renal disease, gender, donor source, type of renal replacement therapy prior to transplantation, or rejection events.