PREVALENCE AND RISK-FACTORS FOR OSTEOPENIA IN DIALYSIS PATIENTS

Dialysis patients are at risk for low bone mineral density (BMD) conse quent of hyperparathyroidism, 1,25-dihydroxyvitamin D deficiency, prev ious immunosuppression, chronic acidosis, secondary amenorrhea, and ch ronic heparin and aluminum exposure. We wanted to determine the preval ence and distribution of osteopenia and the influence of risk factors for osteopenia in dialysis patients. Dual energy x-ray absorptiometry was used to record BMD at the lumbar spine (LS), hip, and nondominant forearm. Results were expressed as Z-scores (standard deviations from the mean of a healthy age- and gender-matched reference population). O steopenia was defined as a Z-score worse than -2. In the 250 dialysis patients studied, the prevalence of osteopenia at the LS, femoral neck (FN) and ultradistal radius (UD) was 8%, 13% and 20%, respectively. T he median Z-scores at these sites were all significantly different fro m the healthy reference population median of 0 and were 0.29 (P = 0.00 8), -0.67 (P < 0.001), and -1.01 (P < 0.001), respectively. Previous t ransplantation was associated with as much as a one Z-score lower BMD at the FN (P = 0.0069) and UD (P = 0.0011) and a marginally significan t reduction at the LS (P = 0.0777). Previous parathyroidectomy was ass ociated with a markedly higher LS BMD (P = 0.0001) and a higher BMD at the FN (P = 0.0017) but not the UD (P = 0.3691). A history of seconda ry amenorrhea was associated with a lower FN BMD (P = 0.0047) but not a significantly lower BMD at the LS (P = 0.0978) or UD (P = 0.2327). I n hemodialysis patients without a history of transplantation, parathyr oidectomy, or secondary amenorrhea, there was no correlation between 2 -score at any site and duration of dialysis. Thus, osteopenia in dialy sis patients occurs in both axial and appendicular sites and sites of compact and cancellous bone. It is more common with previous transplan tation and secondary amenorrhea, whereas a history of parathyroidectom y is associated with increased BMD. No relationship was found between BMD and duration of hemodialysis, which suggests that important change s in BMD occur during the predialysis stage of chronic renal failure. (C) 1996 by the National Kidney Foundation, Inc.