BACKGROUND: Dysnatremia is a risk factor for poor outcomes. We aimed to describe the prevalence and outcomes of various dysnatremia in hospitalized patients. High-risk patients must be identified to improve the prognosis of dysnatremia.

MATERIAL AND METHODS: This prospective study included all adult patients admitted consecutively to a university hospital between October 1, 2014 and September 30, 2015.

RESULTS: All 90 889 patients were included in this study. According to the serum sodium levels during hospitalization, the incidence of hyponatremia and hypernatremia was 16.8% and 1.9%, respectively. Mixed dysnatremia, which was defined when both hyponatremia and hypernatremia happened in the same patient during hospitalization, took place in 0.3% of patients. The incidence of dysnatremia was different in various underlying diseases. Multiple logistic regression analyses showed that all kinds of dysnatremia were independently associated with hospital mortality. The following dysnatremias were strong predictors of hospital mortality: mixed dysnatremia (OR 22.344, 95% CI 15.709–31.783, P=0.000), hypernatremia (OR 13.387, 95% CI 10.642–16.840, P=0.000), and especially hospital-acquired (OR 16.216, 95% CI 12.588–20.888, P=0.000) and persistent (OR 22.983, 95% CI 17.554–30.092, P=0.000) hypernatremia. Hyponatremia was also a risk factor for hospital mortality (OR 2.225, 95% CI 1.857–2.667). However, the OR increased to 56.884 (95% CI 35.098–92.193) if hyponatremia was over-corrected to hypernatremia.

CONCLUSIONS: Dysnatremia was independently associated with poor outcomes. Hospital-acquired and persistent hypernatremia were strong risk factors for hospital mortality. Effective prevention and proper correction of dysnatremia in high-risk patients may reduce the hospital mortality.

Keywords: Adolescent, Hospitalized, Hypernatremia, Hyponatremia, Mortality