Risk factors for vertebral fractures in renal osteodystrophy

Abstract

We determined the prevalence of vertebral fractures in hemodialysis (HD) patients, investigated whether low bone mineral density (BMD) is predictive of vertebral fracture, and evaluated the effect of serum intact parathyroid hormone (iPTH) and alkaline phosphatase (ALP) levels on vertebral fracture. One hundred eighty-seven male HD patients were assessed for vertebral fractures, and lumbar-spine and total-body BMD were measured by dual-energy x-ray absorptiometory. Thirty-nine patients (20.9%) had vertebral fractures. Each standard deviation (SD) decrease in lumbar-spine BMD increased the age-adjusted odds ratio of vertebral fracture 2.0 times (95% confidence interval [CI], 1.4 to 2.0) and 1.6 times (95% CI, 1.1 to 1.6) for total-body BMD. The area under the receiver operating characteristic curve for lumbar-spine BMD was significantly greater than that for total-body BMD (P < 0.05). Patients with serum iPTH levels in the lowest tertile had a 2.4-fold greater risk for vertebral fracture than those in the middle tertile and a 1.6-fold greater risk than those in the highest tertile (P < 0.05). When the two criteria of lowest tertile of serum iPTH level and highest tertile of serum ALP level were combined, the prevalence of vertebral fractures was the greatest. Similarly, when the lowest tertile of serum iPTH level and lowest tertile of serum ALP level were combined, the prevalence was the second greatest among the combined groups according to tertiles of serum iPTH and ALP levels. We conclude that low lumbar-spine BMD might be a sensitive predictor of vertebral fracture in HD patients, and patients with relatively low iPTH levels would have a greater risk for vertebral fracture than those with hyperparathyroidism.