Residual urinary volume is a predictor of overhydration in patients on peritoneal dialysis

Fluid overload is linked to hypertension and cardiovascular diseases in patients on peritoneal dialysis (PD). It is important to monitor the residual urinary volume in patients with end-stage renal disease (ESRD). In fact, fluid overload and residual urinary volume have been considered the risk factors of mortality in ESRD patients on PD. However, the relationship between residual urinary volume and fluid overload was still controversial. Therefore, the objective of this cross-sectional study was to evaluate the association between residual urinary volume and the volume status of PD patients. Body composition was measured using a portable multifrequency whole-body bioimpedance assessment. Relative overhydration was defined when the ratio of overhydration to extracellular water was > 0.15. We examined 75 patients, with a mean age of 50.7 years and mean body mass index of 23.5 kg/m(2). Dialysis vintage was 46.5 months. The patients were divided into the anuric group (n = 30; urine output ≤ 100 mL/day) and the group of urine output > 100 mL/day (n = 45). The anuric group showed higher degree of relative overhydration compared to the patients with the urine output of > 100 mL/day (p = 0.020). In a multivariable linear regression analysis, anuria, diabetes, and serum albumin level were independently associated with relative overhydration. In conclusion, volume status should be closely monitored in anuric patients, and the preservation of residual urinary volume is one of important goals to maintain volume status in PD patients.