Prevalence and causes of low bone density and fractures in kidney transplant patients

Osteoporosis is known to occur in patients with kidney transplants, but lim ited information is available about the prevalence and causes of this compl ication. We asked all 330 patients with kidney transplants in our unit to p articipate in this study of whom 165 (50%) agreed to do so. The characteris tics of the participating patients were similar to the remaining 165 nonpar ticipants. Seventy of 165 (42%) of the participants were women of whom 40 w ere postmenopausal in contrast to the men of whom only one was hypogonadal. Bone mineral density (BMD) was significantly reduced at the radius (Z scor e, -1.5) and femoral neck (Z score, -0.7), but the lumbar spine was normal. BMD was lower in women than men at all skeletal sites. Osteoporosis was fo und in 10-44% and osteopenia was found in 35-50% of women depending on the site. BMD was related inversely to time since transplantation and cumulativ e prednisolone dose. Twenty-seven of the 165 (16%) patients had either vert ebral deformities or a history of a low trauma fracture after transplantati on. This fracture group consisted of 10/27 (37%) men and 17/27 (63%) women, of whom 14 were postmenopausal. Fracture patients tended to be older and h ave a longer duration of renal failure, dialysis, transplantation, greater cumulative steroid dose, and higher bone resorption markers than the nonfra cture group. No differences were found for cumulative doses of cyclosporin or tacrolimus. Logistic regression showed that only duration of dialysis an d time since transplantation significantly increased fracture risk, with od ds ratio (OR) for each year of dialysis or transplantation being 1.21 (CI, 1.00-1.48) and 1.14 (CI, 1.05-1.23), respectively. These data show that low bone density and fractures are common in patients with kidney transplant a nd are determined by both pre- and posttransplant variables. Fracture risk was greatest in women, particularly if they were postmenopausal and we reco mmend that this subgroup is targeted for assessment and treatment.