[Usefulness of bioelectric impedance as a method for evaluating body composition of patients on peritoneal dialysis].

The aim of a study was to evaluate the usefulness of bioelectric impedance as a method of body composition analysis in patients treated with CAPD, with the special attention paid on hydration status and lean body mass. The values of parameters obtained by bioelectric impedance and other methods were compared. The impact of peritoneal dialysis fluid in peritoneal cavity on bioimpedance measurement results were also analyzed. The study was performed in 33 patients dialyzed with CAPD for mean period of 12.3 months, aged between 23 and 72 years (mean 50.9 years). Bioimpedance measurements were also performed in 10 healthy volunteers. The significant impact of 2-liters dialysate volume on measurement results was found. The percentage water contain as well as LBM are under this condition higher (59.2% vs. 58.3%; p < 0.005 and 80.73 vs. 79.6; p < 0.01, respectively), and body fat--lower (19.07 vs. 20.39%; p < 0.005) as compared to empty peritoneal cavity. We also found, that the values of body water obtained from BEI measurements are higher as compared to those calculated from Watson formulas and lean body mass values obtained from BEI analysis are higher as compared to those derived from creatinine kinetics (39.4 vs. 36.96 I.; p < 0.05 and 53.7 vs. 51.1 kg; p < 0.01, respectively). Total and lean body mass did not differ from the values predicted in the treatment group, however the percentage contain of body water was significantly higher (58.34 vs. 51.39%; p < 0.0001). No significant differences were found between body composition of CAPD patients and control individuals.