LONG-TERM BONE LOSS IN KIDNEY-TRANSPLANT RECIPIENTS - A CROSS-SECTIONAL AND LONGITUDINAL-STUDY

Organ transplantation is associated with an early bone loss that subse quently increases the risk of osteopenia and bone fractures. It is not known whether bone loss continues in long-term survivors, but persist ent bone demineralization could further jeopardize an already diminish ed bone mass. To better define long-term bone status of kidney transpl ant recipients (KTR), we conducted cross-sectional and longitudinal ev aluations of bone mineral density (BMD) in 70 KTR with a mean posttran splantation time of 8.1 years, BMD was determined by dual-energy X-ray absorptiometry and was repeated in 55 of the patients after a mean fo llow-up period of 22 +/- 5 months. Lumbar and femoral osteopenia, defi ned as a BMD lower than 2 standard deviations from mean value of sex- and age-matched controls, was present in 28.6% and 10.5% of patients, respectively. There was a significant negative correlation between cum ulative prednisone dose and adjusted lumbar as well as femoral BMD (R = 0.45, P < 0.001 and R = 0.29, P < 0.05, respectively). Five patients had a vertebral BMD below a fracture threshold of 0.777 g/cm(2). Vert ebral fractures (VF) were found in four men and were associated with h igher prednisone dosage (P < 0.05), larger cumulative prednisone dose (P < 0.05), and significantly lower BMD values. According to World Hea lth Organization recent criteria for women, prevalences of lumbar and femoral osteopenia and lumbar and femoral osteoporosis in female patie nts reach 75%, 65%, 33%, and 10%, respectively. The longitudinal part of the study showed a persistent pathological lumbar demineralization process. Over the study period, BMD, expressed as a percentage of that of controls, decreased from 89 +/- 14% to 86 +/- 14% (P < 0.001). Ann ual change of bone mass was -1.7 +/- 2.8% per year. Accelerated verteb ral bone loss (defined as a decrease of BMD, expressed as a percentage of that of controls, of more than 1% per year) was present in 56% of patients and was associated with higher prednisone dosage (P < 0.01). In conclusion, although VF are relatively infrequent in long-term surv ivors of renal transplantation, osteopenia is a frequent finding, and a substantial proportion of women present lumbar osteoporosis. An ongo ing demineralization process of the spine is also demonstrated and pro bably contributes to long-term spinal osteoporosis incidence. Predniso ne dosage remains the most constantly isolated risk factor. (C) 1996 b y the National Kidney Foundation, Inc.