Abstract: Objective The aim of this study was to validate the multifrequency bioelectrical impedance analysis (MBIA) for assessment of fluid status and volume overload in peritoneal dialysis (PD) patients. Methods Sixty-one clinically stable patients undergoing PD were enrolled in the study. In addition to routine blood tests, various body fluid components were measured in PD patients by using the InBody 720 instrument. Dialysis adequacy, renal function and N-terminal pro brain natriuretic peptide (N-proBNP) level were also assessed in these patients. Results In this cross-sectional study, the ratio of extracellular water (ECW) to total body water (TBW) was positively correlated with age (r=0.514, P=0.000) and negatively correlated with serum albumin concentration (r=-0.483, P=0.000). The ECW/TBW ratio was higher in diabetic patients (t=-3.488, P=0.001), cardiovascular disease patients(t=-2.176, P=0.034) and edema patients (t=-2.546, P=0.014) than in other patients (P＜0.05). Multiple stepwise regression model showed that lower serum Alb (β = - 0.386, P＜0.001) and older age (β =0.426, P＜0.001) were the independent influential factors for higher ECW/TBW ratio. ECW/TBW ratio was positively correlated with NT-proBNP (r=0.397, P=0.002). ROC analysis showed that ECW/TBW ratio and NT-proBNP level could effectively predict volume overload, and ECW/ TBW ratio may be better for the prediction. Conclusions Normal ECW/TBW ratio may be affected by age, albumin level and associated diseases. ECW/TBW ratio and serum NT-proBNP level are closely correlated. Both of them can be used to diagnose volume overload in PD patients, and ECW/TBW ratio may be better than NT-proBNP for the diagnosis. ECW/TBW ratio appears to be an easy and useful marker for the estimation of dry body weight in PD patients with various clinical backgrounds.

Key words: Multifrequency bioelectrical impedance analysis, Peritoneal dialysis, N-terminal pro brain natriuretic peptide, Volume overload