A commentary on ‘The efficacy and safety of low dialysate sodium levels for patients with maintenance hemodialysis: a systematic review and meta-analysis’

End-stage renal disease (ESRD) affects up to 15% of the adult population that is associated with increased cardiovascular complication¹. Hypertension can be present in up to 90% of people with ESRD². The survival rate of dialysis patients is relatively poor, and the prognosis is worse than of similar to numerous common cancers. Doctors who take care of hemodialysis patients must choose a proper amount of sodium for cleaning the patient’s blood with dialysate.

Geng et al.³ performed a systematic review and meta-analysis of 12 randomised controlled trials and demonstrated that low dialysate [Na⁺] reduced mean arterial pressure, interdialytic weight gain and predialysis serum [Na⁺] significantly; it also indicated that low dialysate [Na⁺] could increase the incidence of intradialytic hypotension and intradialytic cramps events.

The comprehensive impact of these factors on overall individual experience together with clinical outcomes is still unclear. The impact of such therapy requires careful consideration. On the one hand, this may be beneficial, owing to these variations may reveal a decrease in the content of sodium in the whole body, thus enhancing the cardiovascular structure and the function, lowing cardiovascular death and incidence rate⁴. Nevertheless, another consideration is that the reduction of serum [Na⁺] may represent a signal of injury, and the raise of hypotension in dialysis is the reason for the decrease of hemodialysis effectiveness, cardiac injury as well as eventually the raise of cardiovascular death and incidence rate^5,6. Additionally, apart from spasms and hypotension during dialysis, there is little data to gain a deeper understanding of patient-centered outcomes, and there is low-quality evidence to support higher instead of lower dialysate [Na⁺].

A question might be asked about a third approach to dialysate [Na⁺]: ‘In practice, why not avoid high or low dialysate [Na⁺] altogether, and simply match dialysate [Na⁺] to serum [Na⁺] to avoid any disruption on haemodialysis?’. This so-called ‘isonatraemic haemodialysis’ requires individualisation of dialysate [Na⁺] so that it is close to the patient’s predialysis serum[Na⁺] and is based upon the sodium set-point paradigm: people maintain themselves in optimal sodium balance above and below which health is compromised. Moreover, an individual’s sodium ‘set point’ can be easily ‘re-set’: normal people who are established on low sodium diets will promptly excrete any administered sodium. For this reason, attempts to define a ‘healthy’ sodium balance from an observed state of balance is meaningless.

No strong recommendation for practice can be made on the basis of these data. These preliminary findings represent potential mechanisms for both benefit and harm from lower dialysate [Na⁺], but the net effect of these physiological processes on patient experiences and outcomes at a population level remains unknown. Until the results of a definitive study are available, a decision on what dialysate [Na⁺] to use will have to be made between every patient and doctor, without definite knowledge of whether lower or higher dialysate [Na⁺] is better for the average patient.

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Author contribution

Y.L.: writing; G.X.: data analysis.

Conflicts of interest disclosure

There are no conflicts of interest.

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Guarantor

Yong Liang.

Data availability statement

None.

Provenance and peer review

Commentary, internally reviewed.