Modification of Dialysate Na+ Concentration but not Ultrafiltration or Dialysis Treatment Time Affects Tissue Na+ Deposition in Patients on Hemodialysis

Abstract

IntroductionTissue Na+ overload is present in hemodialysis (HD) patients and is associated with cardiovascular mortality. Strategies to actively modify tissue Na+ amount in these patients by adjusting the HD regimen have not been evaluated. MethodsIn several sub-studies, including cross-sectional analyses (n = 75 HD patients), a cohort study and a cross-over interventional study (n = 10 patients each), we assessed the impact of ultrafiltration volume, prolongation of dialysis treatment time and modification of dialysate Na+ concentration on tissue Na+ content as determined by 23Na magnetic resonance imaging (23Na-MRI). ResultsIn the cross-sectional analysis of our HD patients, differences in dialysate [Na+] were associated with changes in tissue Na+ content, while neither ultrafiltration volume nor HD treatment time affected tissue Na+ amount. Skin Na+ content was lower in 17 HD patients with dialysate [Na+] of <138 mmol/l compared to 58 patients dialyzing at ≥138 mmol/l (20.7±7.3 vs. 26.0±8.8 a.u., p<0.05). In the cohort study, intra-individual prolongation of HD treatment time was not associated with a reduction in tissue Na+ content. Corresponding to the observational data, intra-individual modification of dialysate [Na+] from 138 to 142 to 135 mmol/l resulted in concordant changes in skin Na+ (24.3±7.6 vs. 26.3±8.0 vs. 20.8±5.6 a.u, p <0.05 each), while no significant change in muscle Na+ occurred. ConclusionSolely adjustment of dialysate [Na+] had a reproducible impact on tissue Na+ content. 23Na-MRI could be utilized to monitor the effectiveness of dialysate [Na+] modifications in randomized-controlled outcome trials.