Mortality Associated with Low Serum Sodium Concentration in Maintenance Hemodialysis

Abstract

BACKGROUND-Low serum sodium concentrations are associated with an increased risk of death in the general population, but causality is uncertain due to confounding from clinical conditions such as congestive heart failure and cirrhosis, in which hyponatremia results from elevated levels of arginine vasopressin.

Dialysate Sodium Concentration and the Association with Interdialytic Weight Gain, Hospitalization, and Mortality

“…We confirmed in the present study population that predialysis SNa was associated inversely with all-cause mortality (hazard ratio [ (17). Because higher IDWG has been associated with a higher mortality risk (21,24), it might be hypothesized that higher DNa also would be associated with higher mortality.…”

“…Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) and a simultaneous report from the Hemodialysis Study have demonstrated that predialysis SNa concentrations are inversely associated with mortality (16,17). Prior DOPPS analyses were restricted to patients with multiple SNa measurements and intriguingly suggested that, for patients with low mean SNa levels, higher DNa prescriptions are associated with lower mortality risk.…”

The Effect of Serum Sodium on Survival in Patients Treated by Peritoneal Dialysis in the United Kingdom

“…Traditionally this risk has been ascribed to underlying co-morbidity, such as congestive cardiac failure, cirrhosis and tumour induced inappropriate ADH syndrome. The situation for patients with chronic kidney disease may be somewhat more complex, with reports of both hyponatraemia and also hypernatraemia associated with increased mortality [10], and although there are reports of increased risk for mortality in hyponatraemic haemodialysis patients [4,5], these reports are biased towards more co-morbid patients because they censored patients who were transplanted from the analyses. Our analyses were more conservative -if we had censored the patients who were transplanted we would have biased our sample to the more ill population, and similarly if we had removed all patients with technique failure from the mortality outcome analysis we would have biased our sample to a more healthy population.…”

“…Incident haemodialysis patients, who were hyponatraemic after adjusting serum sodium measurements for diabetic control were reported to have an increased risk for death [12], whereas others have reported that hyponatraemia does not confer any additional risk for mortality [6] and also in nonhaemodialysis diabetic patients [13]. Similarly some studies in haemodialysis patients reported that mortality reduced for each 4 mmol/l increase in serum sodium [4], although others reported no survival advantage once the serum sodium reached 145 mmol/l [6].…”

“…As with the general population there are several large observational studies reporting that pre-haemodialysis hyponatraemia is independently associated with increased risk of mortality for haemodialysis patients [4,5]. Whether this risk for mortality is directly attributable to hyponatraemia, and reduced body sodium stores, or whether hyponatraemia is acting as a surrogate for an inflammatory state and increased endothelial permeability remains to be determined.…”