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

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.

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.

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.

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.