Determinants of reduced bone mineral density and increased bone turnover after kidney transplantation: cross-sectional study.

AIM To analyze bone metabolism and the risk factors of bone loss in kidney transplant recipients. METHODS The bone mineral density (BMD) of the lumbar spine, femoral neck, and radius was determined by dual-energy X-ray absorptiometry in 52 patients 8 days to 228 months after kidney transplantation. Total and bone alkaline phosphatase (BAP), osteocalcin, procollagen, type I collagen telopeptide, collagen cross links, calcium, intact parathyroid hormone (iPTH), and creatinine were measured in all patients. RESULTS The BMD of the spine and femoral neck was reduced in 57%, and of the radius in 72% of the patients. Reduced BMD was associated with significantly increased levels of iPTH, osteocalcin, and procollagen. Dialysis duration negatively correlated with the radius BMD in all patients and the femoral neck BMD in women. No relationship between BMD and length of post-transplantation time, age, cumulative steroid dose, or serum creatinine level was established. All biochemical parameters negatively correlated with the spine BMD, but not with the BMD of the femoral neck and radius. The correlation between BAP and telopeptide and length of post-transplantation time was also negative. No difference in the incidence of osteopenia was found between genders. CONCLUSION Osteopenia/osteoporosis and increased bone turnover were present in more than a half of the kidney transplant recipients. Reduced BMD was associated with enhanced bone remodeling, primarily mediated by PTH hypersecretion. The length of post-transplantation period, cumulative steroid dose, gender, and age could not be identified as risk factors of reduced BMD.