Residual Renal Function and Effect of Low-Sodium Solution on Blood Pressure in Peritoneal Dialysis Patients

Background:Residual renal function (RRF) affects sodium and fluid balance. The aim of this analysis was to examine the impact of RRF on the effect of a sodium-reduced peritoneal dialysis fluid (PDF) on blood pressure (BP).Methods:This is a post-hoc analysis of a prospective, randomized, controlled double-blind clinical trial with 82 patients on continuous ambulatory PD (CAPD) treated with a low-sodium (125 mmol/L Na) or a standard-sodium (134 mmol/L Na) PDF. Subgroups according to glomerular filtration rate (GFR) at baseline (≤ / > 6 mL/min/1.73 m²) were analyzed for BP and antihypertensive medication.Results:In the low-GFR group on low-sodium PDF (N = 26), systolic BP was reduced from 152 ± 24 mmHg at baseline to 137 ± 21 mmHg at week 12, diastolic BP from 90 ± 16 mmHg to 83 ± 11 mmHg. In the low-GFR group on standard-sodium PDF and in the high-GFR group on both PDF types, only minor changes were observed. For the low-GFR subgroup, the confounder-adjusted mean study group difference in systolic BP at week 12 between low-sodium and standard-sodium PDF was -16.9 (95% confidence interval [CI] -27.2 to -6.6) mmHg, for diastolic BP, it was -7.0 (95% CI -12.6 to -1.4) mmHg. In both GFR subgroups, more patients had a reduced daily dose of antihypertensive medication and fewer patients an increased daily dose in the low-sodium compared with the standard-sodium group at week 12.Conclusions:The reduction of BP with a sodium-reduced PDF seems to be more effective in patients with no or low RRF than in patients with residual capacity of renal sodium and fluid control.