Hyponatremia as a predictor of outcome and mortality: results from a second-level urban emergency department population

Background Hyponatremia is the most common electrolyte disorder and it has been associated with increased mortality. Aims This study evaluated hyponatremia as a prognostic factor for severity and mortality. Methods We compared the prevalence of hyponatremia among patients who died during the year 2017 (from 1 January 2017 to 31 December 2017) with the prevalence of hyponatremia among subgroups of patients, i.e. outpatients, patients hospitalized for more than 2 days and patients admitted in the intensive care unit (ICU). We also described the mortality rate and the prevalence of comorbidities among hyponatremic patients, according to hyponatremia degree (slight, moderate, severe), basal characteristics, comorbidities and their outcome (discharged, hospitalized or died). Results In our population of a public hospital setting, hyponatremia was present at admission in 17% of deaths, and the comparison between hyponatremic and normonatremic patients in terms of mortality confirms the hypothesis that this disorder is in anyway strictly associated with vulnerability and with a poor prognosis. Conclusions We conclude that hyponatremia is a predictive marker for a bad clinical course, therefore patients with this electrolyte disorder should be carefully monitored.