Dialysate Sodium Lowering in Maintenance Hemodialysis

Key Points Treatment to dialysate sodium 135 versus 138 mEq/L led to no difference in the rate of change in intradialytic hypotension, but symptoms were greater in the low arm. Use of a dialysate sodium concentration of 135 versus 138 mEq/L led to a small reduction in interdialytic weight gain, but had no effect on predialysis BP. Raising dialysate sodium concentration from 135 to 140 mEq/L reduced intradialytic hypotension and was associated with a marked increase in BP. Background Lowering dialysate sodium concentration may improve volume and BP control in patients on maintenance hemodialysis. Methods We randomized 42 participants 2:1 to dialysate sodium 135 versus 138 mEq/L for 6 months. This was followed by a 12-week extension phase in which sodium was increased to 140 mEq/L in low-arm participants. The primary outcome was intradialytic hypotension (IDH). Secondary outcomes included dialysis disequilibrium symptoms, emergency room visits/hospitalizations, interdialytic weight gain, and BP. Longitudinal changes across arms were analyzed using linear mixed regression. Results Treatment to dialysate sodium 135 versus 138 mEq/L was not associated with a difference in a change in the rate of IDH (mean change [95% confidence interval], 2.8 [0.8 to 9.5] versus 2.7 [1.1 to 6.2] events per 100 treatments per month); ratio of slopes 0.96 (0.26 to 3.61) or emergency room visits/hospitalizations (7.3 [2.3 to 12.4] versus 6.7 [2.9 to 10.6] events per 100 patient-months); difference 0.6 (−6.9 to 5.8). Symptom score was unchanged in the 135 mEq/L arm (0.7 [−1.4 to 2.7]) and decreased in the 138 mEq/L arm ([5.0 to 8.5 to 2.0]; difference 6.0 [2.1 to 9.8]). Interdialytic weight gain declined in the 135 mEq/L arm and was unchanged in the 138 mEq/L arm (−0.3 [−0.5 to 0.0] versus 0.3 [0.0 to 0.6] kg over 6 months; difference [−0.6 (−0.1 to −1.0)] kg). In the extension phase, raising dialysate sodium concentration from 135 to 140 mEq/L was associated with an increase in interdialytic weight gain (0.2 [0.1 to 0.3] kg) and predialysis BP (7.0 [4.8 to 9.2]/3.9 [2.6 to 5.1] mm Hg) and a reduction in IDH (odds ratio, 0.66 [0.45 to 0.97]). Conclusions Use of a dialysate sodium concentration of 135 as compared with 138 mEq/L was associated with a small reduction in interdialytic weight gain without affecting IDH or predialysis BP, but with an increase in symptoms. Raising dialysate sodium concentration from 135 to 140 mEq/L was associated with a reduction in IDH, small increase in interdialytic weight gain, and marked increase in predialysis BP. Clinical Trial registration number NCT03144817.