Abstract: 【Abstract】Objective of this study was to study the characteristics of fluid distribution by using multifrequency bioelectrical impedance in maintenance hemodialysis (MHD) patients before and after dialysis. Methods A total of 86 MHD patients who reached the target of clinical dry weight were selected as the experiment group. Meanwhile, a total of 258 healthy cases were recruited as the control group. Body weight (W), total body water (TBW), intracellular water (ICW) and extracellular water (ECW) before and after a dialysis session were measured by using a multi-frequency body composition analyzer. ICW/W, ICW/TBW, ICW/ H2, ECW/W, ECW/TBW, ECW/H2 and ICW/ECW before and after a dialysis session were then calculated. Results Before dialysis, ECW/H2 was significantly higher in experiment group than in control group (4.77± 0.58 vs. 4.52±0.36 in males, P＜0.01; 4.16±0.47 vs. 3.97±0.32 in females, P＜0.01). After dialysis in experiment group, ECW/H2 approximated to that of control group. Before and after a dialysis session in experiment group, there were no significant differences in ICW/TBW, ICW/ECW and ECW/TBW. Between experiment group and control group. For ICW/H2 in males, the level in experiment group before dialysis was higher than that in control group (9.42±1.26 vs. 9.03±0.75, P＜0.05), and the level after dialysis approximated to that of control group (8.83±1.15 vs. 9.03±0.75, P＞0.05). For ICW/H2 in females, the level before dialysis was significantly higher than that after dialysis (8.07±0.79 vs. 7.52±1.49, P＜0.05). Conclusion ①In MHD patients, water was retained not mainly in extracellular space but in both extracellular and intracellular spaces. Dialysis by ultrafiltration decreased the water retention in both extracellular and intracellular spaces. ②ECW/ H2 and ICW/H2 decreased closely to those of normal persons after dialysis. Therefore, ECW/H2 and ICW/H2 may represent water load status in MHD patients, and need to be further studied.

Key words: Bioelectrical impedance, Hemodialysis, Body fluid distribution, Intracellular water, Extracellular water