Hyponatremia and hypernatremia in the emergency department: severity and outcomes

Otterness, Karalynn; Singer, Adam J; Thode, Henry C; Peacock, W. Frank

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Clin Exp Emerg Med > Accepted Articles

Original Article

doi: https://doi.org/10.15441/ceem.22.380 [Accepted]

Hyponatremia and hypernatremia in the emergency department: severity and outcomes

Karalynn Otterness¹, Adam J Singer¹, Henry C Thode¹, W. Frank Peacock²

¹Department of Emergency Medicine, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, USA
²Department of Emergency Medicine, Baylor College of Medicine, Houston, TX, USA

Correspondence Karalynn Otterness Email: karalynn.otterness@stonybrookmedicine.edu

Received: September 28, 2022. Revised: January 14, 2023. Accepted: January 16, 2023. Published online: January 30, 2023.

ABSTRACT

Background
Hyponatremia and hypernatremia are common electrolyte disorders. Few studies to date have focused on patients presenting to the emergency department (ED) with sodium (Na) disorders. Our objective was to determine the incidence and outcomes of hyponatremia and hypernatremia in ED patients.
Methods
This study was a retrospective, single-center review of electronic medical records at an academic suburban ED with approximately 100,000 annual visits. Subjects included consecutive adult ED patients with Na levels measured while in the ED in 2019. Demographic, clinical, and laboratory data were recorded. Outcomes data, including hospital admission, intensive care unit (ICU) admission, mortality, and length of stay (LOS), were recorded. The primary outcome was in-hospital death. Secondary outcomes were hospital admission, ICU admission, ED LOS, and hospital LOS. Univariable and multivariable linear and logistic regression analyses were performed to explore the association of candidate predictor variables and outcomes.
Results
Na was measured in 57,427 adults (54%) among a total of 106,764 assessed ED visits in 2019. The mean (standard deviation) age was 54 (21) years, and 47% of participants were male. Mild, moderate, and severe hyponatremia and hypernatremia occurred in 8%, 2%, and 0.1% of patients and 1%, 0.2%, and 0.1% of patients, respectively. Hospital and ICU admission and mortality rates increased as Na levels increased or decreased further from normal. Odds ratio (95% confidence interval) values for hospital mortality were 2.39 (1.97–2.90) for mild hyponatremia, 3.93 (2.95–5.24) for moderate hyponatremia, 6.98 (2.87–16.40) for severe hyponatremia, 3.65 (2.47–5.40) for mild hypernatremia, 8.58 (4.92–14.94) for moderate hypernatremia, and 55.75 (11.37–273.30) for severe hypernatremia. Hypernatremia was associated with a greater risk of death than hyponatremia. Compared to normal Na levels, the adjusted odds ratio (95% confidence interval) values associated with mortality from hyponatremia were as follows: mild, 2.39 (1.97–2.90); moderate, 3.93 (2.95–5.24); and severe, 6.98 (2.87–16.40). Separately, those associated with mortality from hypernatremia relative to normal Na levels were as follows: mild, 3.65 (2.47–5.40); moderate, 8.58 (4.92–14.94); and severe, 55.75 (11.37–273.30). Patients with hypo- and hypernatremia had increased LOS times compared to those with normal Na levels.
Conclusions
Hyponatremia and hypernatremia were associated with greater rates of hospital admission, ICU admission, and mortality and prolonged hospital LOS times.

Keywords: hypernatremia, hyponatremia, emergency department