Body composition changes in chronic hemodialysis patients before and after hemodialysis as assessed by dual-energy X-ray absorptiometry

The aim of this study was to investigate the effect of hemodialysis on body composition assessment by dual-energy x-ray absorptiometry (DEXA). Seventeen patients with chronic renal failure who were on a regular hemodialysis schedule were studied. Body weight and body composition were assessed immediately before and approximately 1 hour after a typical hemodialysis session. Body weight was assessed by means of an electronic balance. Body composition measurements were made by DEXA. Whole-body and subtotal (head and neck excluded) analysis assessed the following parameters: body weight, bone mineral density (BMD), bone mineral content (BMC), and fat (FTM)and lean (LTM) tissue mass. BMC, FTM, and LTM were estimated separately for the trunk, arms, and legs. The mean body weight reduction after hemodialysis was 2.8 +/- 1.1 kg (mean +/- SD). Concerning whole-body analysis, no change was observed in mean BMC and FTM after hemodialysis. On the contrary, a significant reduction was observed in mean body weight as assessed by DEXA (before hemodialysis, 65.0 +/- 11.4 kg; after, 62.2 +/- 10.9 kg, P=.0003), as well as in mean LTM (before hemodialysis, 42.7 +/- 9.4 kg; after, 39.7 +/- 9.0 kg, P=.0003). Similar results were obtained from subtotal and regional analysis. Body weight changes as measured by the electronic balance exhibited a strong positive correlation with the changes in both body weight and LTM as assessed by DEXA (r=.989, standard error of the estimate [SEE]=0.167 kg and r=.941, SEE=0.382 kg, respectively, P<.0001). It is concluded that gravimetric changes induced by hemodialysis are highly correlated with LTM changes and are not associated with changes in BMC or FTM estimated by DEXA. Copyright (C) 1997 by W.B. Saunders Company.