Body composition measurements using bioimpedance analysis in peritoneal dialysis patients are affected by the presence of dialysate

The presence of peritoneal dialysate when performing bioimpedance analysis may affect body composition measurements. The aim of this study was to evaluate the impact of dialysate on body composition measurements in Asians. Forty-one patients undergoing maintenance peritoneal dialysis in our hospital peritoneal dialysis unit were included in this study. Dialysate was drained from the abdomen prior to measurement, and bioimpedance analysis was performed using multi-frequency bioimpedance analysis, with each subject in a standing position (D-). Dialysate was then administered and the measurement was repeated (D+). The presence of peritoneal dialysate led to an increase in intracellular water (ICW), extracellular water (ECW), and total body water (D-: 20.33 +/- 3.72L for ICW and 13.53 +/- 2.54L for ECW; D+: 20.96 +/- 3.78L for ICW and 14.10 +/- 2.59L for ECW; P<0.001 for both variables). Total and trunk oedema indices were higher in the presence of peritoneal dialysate. In addition, the presence of peritoneal dialysate led to an overestimation of mineral content and free fat mass (FFM) for the total body; but led to an underestimation of body fat (D-: 45.80 +/- 8.26kg for FFM and 19.30 +/- 6.27kg for body fat; D+: 47.51 +/- 8.38kg for FFM and 17.59 +/- 6.47kg for body fat; P<0.001 for both variables). Our results demonstrate that the presence of peritoneal dialysate leads to an overestimation of FFM and an underestimation of fat mass. An empty abdomen is recommended when evaluating body composition using bioimpedance analysis.