A comparison of quantitative computed tomography and dual x-ray absorptiometry for evaluation of bone mineral density in patients on chronic hemodialysis

Chronic renal failure leads to a reduction of bone mineral density (BMD). T herefore, noninvasive methods to evaluate BMD are also used regularly in th is patient population. In this study, we compared the results of two widely used methods, quantitative computed tomography (QCT) of the lumbar spine a nd dual x-ray absorptiometry (DXA) at different sites in 90 patients on chr onic hemodialysis. Additionally, we also determined various clinical and bi ochemical data to assess their relationship to BMD at the different measure ment sites. A total of 75% of our patients was found to have reduced BMD, a nd 25% had an average z-score below -2. Z-scores obtained by the different methods and at the different measurement sites within an individual patient varied considerably from completely normal to severely reduced values. Mul tivariate analyses using clinical and biochemical parameters showed lower v alues of BMD at all measurement sites after transplantation and marginally higher values after parathyroidectomy, which was seen only in DXA measureme nt at the femoral neck. We conclude from our study that determination of BM D in chronic hemodialysis patients yields highly variable results, dependin g on the technique used. As long as the exact clinical relevance of these r esults has not been determined, regular routine measurement of isolated sit es of BMD cannot be advocated in this patient population, (C) 2001 by the N ational Kidney Foundation, Inc.