The importance of residual renal function in peritoneal dialysis.

Background: Peritoneal dialysis (PD) patients with preserved residual diuresis have a lower risk of death and complications. Here we analyzed associations between residual diuresis and presence of fluid overload and biomarkers of cardiac strain and nutrition in PD patients.
Methods: Among 44 PD patients placed into three subgroups, depending on volume of residual diuresis (group A ≤ 500; group B 600-1900; and group C ≥ 2000 mL/day), we examined: overhydration (OH) assessed by bioimpedance analysis (BIA; yielding OH index OHBIA) and by clinical criteria (edema and hypertension); nutritional status (by subjective global assessment, SGA); metabolic status (electrolytes, serum lipid profile, CRP, and albumin); biomarkers of fluid overload and cardiac strain (N-terminal probrain natriuretic peptide, NT-proBNP, and troponin T, TnT); and, echocardiography and chest X-ray.
Results: With increasing residual diuresis in group A, B and C, fewer patients had signs of overhydration defined as OHBIA > 1.1 L (75.0, 42.9 and 33.3 %) or peripheral edema (25.0, 21.4 and 0 %) and NT-proBNP (15199 ± 16150 vs. 5930 ± 9256 vs. 2600 ± 3907 pg/mL; p < 0.05) and TnT (0.15 ± 0.17 vs. 0.07 ± 0.09 vs. 0.04 ± 0.03 ng/mL; p < 0.05) were significantly lower. Significant differences were found also in ejection fraction, SGA, and total cholesterol, albumin and hemoglobin levels whereas blood pressures and serum CRP did not differ significantly.
Conclusion: Signs of OH and cardiac strain are common in PD patients, even in those with diuresis of 1000-2000 mL/day and with no clinical signs or symptoms, suggesting that even moderate decrease in residual renal function in PD patients associate with OH and other complications.