Diameter of Inferior Caval Vein and Impedance Analysis for Assessment of Hydration Status in Peritoneal Dialysis

: In 19 stable peritoneal dialysis (PD) patients, hydration status was evaluated by measurement of vena cava diameter (VCD) and bioelectrical impedance analysis (BIA) variables: intracellular water (ICW), extracellular water (ECW), and total body water (TBW). We investigated whether BIA can replace VCD. VCD did not correlate with TBW but correlated moderately with ECW/TBW (r = 0.42; 0.025 < p < 0.05) and ICW/ECW (r = −0.47; p < 0.025). Patients with underhydration (n = 4; VCD 1.50) and ECW/TBW (11.5 mm/m2): ICW/ECW (0.40). Although the positive predictive value of ICW/ECW and ECW/TBW for both under‐ and overhydration was only 50% and 54%, respectively, there were no false negative values. Although BIA cannot replace VCD in PD patients, the reverse holds true as well. Combining BIA and VCD may lead to a better estimation of hydration status because both techniques provide complementary information.