Bone mineral density, biochemical markers and skeletal fractures in haemodialysis patients.
BACKGROUND: End-stage renal disease is often associated with altered bone metabolism. METHODS: In order to investigate the determinant factors of bone mineral density (BMD) and the risk factors of fractures, we studied 70 patients; 26 women (23 post-menopausal) and 44 men, (mean+/-SD) aged 60.5+/-14.3 years, treated by standard haemodialysis (HD) for 6.4+/-6.8 years. Main circulating bone biochemical markers were assessed and BMD was measured with a Lunar DPX densitometer at five sites. BMD results are expressed as a function of age and gender (Z-score). RESULTS: Mean Z-score was markedly decreased at the mid-radius (-2.75+/-1.23) whereas it was normal at the femoral neck (-0.42+/-1.13) and lumbar spine (0.02+/-2.13), and total body (-0.62+/-1.53). Time on HD was negatively correlated to the Z-score at the mid-radius and total body but not at the other sites. Serum intact parathyroid hormone (iPTH), whole PTH or cyclase activating PTH (CAP) and bone-specific alkaline phosphatase concentrations were negatively correlated with Z-scores at all sites. Twenty-one out of 70 patients had sustained a total of 27 fractures since the beginning of dialysis therapy (seven ribs, seven ankles, six vertebrae, three humerus, two wrists and two hips). They had a total body Z-score significantly lower than that of patients without fractures, -1.34+/-1.54 vs -0.37+/-1.46, respectively (P<0.031); however, their Z-scores at the other sites were not different. They were on HD for longer time, 10.4+/-9.5 vs 5.0+/-5.1, respectively (P<0.003), and the relative risk of skeletal fractures was 6.4 times greater after 10 years of HD. The seven patients with rib fractures had a decreased Z-score at most of the sites but not at the mid-radius. Rib fractures but no other fractures were associated with markedly decreased body weight, fat mass and serum leptin levels. CONCLUSIONS: In conclusion, the Z-score at the mid-radius was decreased in HD patients and correlated with high serum PTH but not with fractures. Bone fractures were associated with the time passed on HD and with a low total body Z-score. Rib fractures were frequent and associated with a poor nutritional state.