Ye X, et al. - Researchers explored how serum sodium (SNa) variability metrics are associated with all-cause mortality in a large patient population from the international MONitoring Dialysis Outcomes (MONDO) Initiative. They included all adult incident patients from the MONDO database with more than 5 SNa measurements during the first year on HD and calculated the following variability indicators during baseline: mean SNa and its SD; average real variability (ARV, average the absolute distance of the 2 consecutive SNa measurements), and average directional range (DR, the difference between minimum and maximum values). Findings revealed the association of higher SNa variability with increased all-cause mortality at all levels of SNa. Mortality was noted to be most strongly associated with DR of SNa and thus it seems to constitute the simple and novel prognostic indicator, easily applicable at the bedside.