Retrospective Analysis of Clinical Effects Following Reduction in Dialysate Sodium in Patients on Long-Term Hemodialysis

Background: Dialysate sodium (NaD) influences fluid balance and blood pressure (BP) in hemodialysis (HD). While lowering NaD has been associated with improved BP control and reduced IDWG, the underlying mechanisms are not fully understood. We explored the clinical and biochemical effects of reducing NaD in a long-term HD population. Methods: This was a retrospective study of chronic, thrice-weekly (TIW) ICHD patients at an urban Northern California center before and after NaD reduction from 145 to 138 mEq/L. Included patients had no residual kidney function and ≥1 year of HD on both NaD levels. Data on weight (wt), inter-dialytic weight gain (IDWG), pre-/post-HD BP, and anti-HTN lists were collected for 1 year before and after the change. During low NaD period, patients were observed by whether serum sodium (NaS) was above or below NaD to assess differences in fluid status and BP. Serum osmolality (osm) was calculated from monthly labs. Paired and unpaired t-tests were used where appropriate. Results: We identified 130 patients on TIW ICHD who met inclusion criteria. Mean lab, hemodynamic, and wt data are shown in Table 1. Anti-HTN medication list did not differ significantly before vs. after the NaD change. During the low NaD period, 67 patients had pre-HD serum sodium (NaS) ≤ NaD and showed persistently lower serum osmolality compared to those with NaS > NaD, both before and after the NaD change. Conclusion: Lower NaD was associated with improved BP control and reduced IDWG. While serum osm had statistically significant decrease after NaD change, the difference was small. Patients maintained similar serum Na and osm across both NaD periods, suggesting that the benefits of lower NaD may not be driven by serum osm and that patients may have individual osm set points. Table 1 - High NaD Low NaD p-value Serum Sodium (mEq/L) 138.2 ± 2.9 138.3 ± 2.6 0.67 Serum Albumin (g/dL) 3.8 ± 0.4 3.8 ± 0.4 0.93 Post HD Wt (kg) 71.0 ± 24.2 71.1 ± 25.4 0.89 IDWG (kg) 3.4 ± 1.8 2.7 ± 1.1 <0.001 Calculated Serum Osm 302 ± 8 300 ± 8 0.02 Pre-HD Systolic BP 157 ± 18 152 ± 20 <0.001 Pre-HD Diastolic BP 85 ± 12 81 ± 13 <0.001 Post-HD Systolic BP 144 ± 16 138 ± 16 <0.001 Post-HD Diastolic BP 78 ± 9 74 ± 11 <0.001 Pre-HD MAP 109 ± 13 104 ± 14 <0.001 Post-HD MAP 100 ± 11 95 ± 11 <0.001