Bone loss after kidney transplantation: a longitudinal study in 115 graft recipients.

BACKGROUND: Bone loss is an important problem in renal transplant recipients immediately after surgery. No data are available about the bone loss beyond the first post-transplantation year. METHODS: In a longitudinal, uncontrolled observational study bone mineral density (BMD) was measured by dual X-ray absorptiometry in 115 renal graft recipients starting at different times after transplantation (0-20 years after transplantation) with a follow-up time of 12 months. RESULTS: A total of 56 patients showed a reduction of BMD during the observation period. Bone loss depended on the time after transplantation. Mean reduction of BMD at lumbar spine was 7 +/- 10%, 1 +/- 9% during the first and second postoperative year. Beyond the third year bone mineral density did not change or even increased slightly (0 +/- 4% during 3-5th year, 1 +/- 6% during 6-10th year and 2 +/- 4% during 11-20th year after transplantation). Decrease of BMD correlated with a higher mean daily prednisone dosage (P < 0.001), a higher cumulative prednisone dose (P < 0.01), a more frequent and more steroid-resistant rejection (P < 0.001) and a higher initial parathyroid hormone level (P < 0.001). Patients with 25-OH-cholecalciferol therapy (P < 0.05) or more physical activity (P < 0.05) had a smaller bone loss. CONCLUSIONS: Reduction of BMD after transplantation is highest within the first post-transplant year. The effects of acute graft rejection, prednisone dosage and initial parathyroid hormone level are predominant among the multiple factors associated with pronounced bone loss.