Characteristics of Patients With Severe Hypochloremia in the Emergency Department: A Single Center Retrospective Study

ABSTRACT Background and Aims Hypochloremia is an electrolyte disturbance in which the serum chloride concentration is abnormally low. Hypochloremia is associated with poor outcomes in critically ill patients in the intensive care unit (ICU) and coronary care unit (CCU), but little is known about its prevalence and prognosis in the emergency department (ED). We investigated the real‐world prevalence and prognosis of severe hypochloremia in the ED. Methods All adult patients (18 years old or older) with serum chloride levels measured at our ED between 2018 and 2023 were included. Hypochloremia and severe hypochloremia were defined as a serum chloride level of ≦97 and ≦80 mEq/L, respectively. Information collected included age, sex, serum chloride, and serum creatinine. Results 11,065 adult patients had their serum chloride measured at the ED. The mean age of patients was 67 ± 20 years, and 53% were male. The mean serum creatinine and eGFR were 1.4 ± 1.8 mg/dL and 66 ± 48 mL/min/1.73 m 2 . The prevalence of hypochloremia and severe hypochloremia was 9.2% and 0.3%, respectively. A total of 8,135 adult patients were admitted, and the 30‐day mortality of patients with normochloremia and hypochloremia was 13% and 23%, respectively ( p < 0.001). A total of 30 patients with severe hypochloremia were admitted, and 10 patients (33%) died within 30 days. Conclusion The 30‐day mortality of patients presenting to the ED with severe hypochloremia was high. Hypochloremia may be associated with poor short‐term outcomes in patients presenting to the ED.