Endocrine Abstracts

Background: Hyponatremia is the most common electrolyte abnormality, it increases morbidity and mortality, but it is not clear if this condition influences mortality independently of other contributing factors. The aim of our study was to assess the relative contribution of hyponatremia to in-hospital mortality and to determine predictive factors associated with hyponatremia-related mortality.

Materials and methods: A database search was conducted for all patients admitted to Fifth Department of Internal Medicine of University Hospital in Bratislava Slovakia, from 1st January 2012 to 31st August 2012. Medical records were reviewed and patients demographics, underlying disease, cause of hyponatremia, and in-hospital deaths were noted. Control group consisted of patients with normonatremia admitted to the same department during the same period matched 1:1 by sex, age and underlying disease. Difference in in-hospital mortality rate between the study and control groups was tested by χ test. Baseline demographics, underlying diseases, cause of hyponatremia, and state of hyponatremia correction as possible risk factors for mortality were tested in a multivariate analysis.

Results: The baseline cohort of all admitted patients consisted of 2171 patients. Hyponatremia was found in 278 (13%) patients (160 females and 118 males). The most common causes of hyponatremia were gastrointestinal loss (52 patients), decreased oral intake (47 patients), and dilution hyponatremia (45 patients). The in-hospital mortality in hyponatremic group was significantly higher compared with control group (22 vs 7%, respectively; OR 3.75, 95% CI 2.17–6.48, P<0.0001). In a multivariate analysis independent factors associated with increased mortality were age above 65 years, dilution hyponatremia and decreased oral intake as etiologic factors of hyponatremia, unsuccessful hyponatremia correction.

Conclusion: Hyponatremia is an independent factor of in-hospital mortality. Age above 65 years, failure to correct hyponatremia and some specific etiologic factors of hyponatremia increase mortality.