Abstract
INTRODUCTION: Tissue Na(+) overload is present in patients receiving hemodialysis (HD) 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. METHODS: In several substudies, including cross-sectional analyses (n = 75 patients on HD), a cohort study and a cross-over interventional study (n = 10 patients each), we assessed the impact of ultrafiltration (UF) volume, prolongation of dialysis treatment time, and modification of dialysate Na(+) concentration on tissue Na(+) content using (23)Na magnetic resonance imaging ((23)Na-MRI). RESULTS: In the cross-sectional analysis of our patients on HD, differences in dialysate sodium concentration ([Na(+)]) were associated with changes in tissue Na(+) content, whereas neither UF volume nor HD treatment time affected tissue Na(+) amount. Skin Na(+) content was lower in 17 patients on HD, 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 arbitrary units [a.u.], P < 0.05). In the cohort study, intraindividual prolongation of HD treatment time was not associated with a reduction in tissue Na(+) content. Corresponding to the observational data, intraindividual 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), whereas no significant change in muscle Na(+) occurred. CONCLUSION: Solely adjustment of dialysate [Na(+)] had a reproducible impact on tissue Na(+) content. (23)Na-MRI could be utilized to monitor the effectiveness of dialysate [Na(+)] modifications in randomized-controlled outcome trials.