Naohiko Imai

Hypernatremia is less common than hyponatremia in emergency department (ED) settings but has been associated with adverse clinical outcomes. While prior studies have primarily focused on critically ill or inpatient populations, data describing hypernatremia at the time of ED presentation remain limited. In particular, the clinical characteristics and early management patterns of patients with severe hypernatremia have not been well characterized in ED settings. We conducted a retrospective cohort study of all adult patients who visited a single tertiary-care emergency department and underwent serum sodium measurement. Patients were categorized by serum sodium level at presentation. For patients with severe hypernatremia, additional clinical data, treatments, serial sodium measurements, and outcomes were collected. Survival analyses were performed using Kaplan-Meier methods and Cox proportional hazards models to evaluate the association between hypernatremia and mortality in the overall cohort. Among 6,818 emergency department visits, 4,917 patients (72%) were hospitalized. Hypernatremia was observed in 4.7% of hospitalized patients. Compared with normonatremia, patients with hypernatremia were older, had significantly impaired renal function, and showed markedly higher in-hospital mortality (44% vs. 14%, p < 0.001). Kaplan-Meier analysis demonstrated significantly lower survival in the hypernatremia group (p < 0.001), and Cox proportional hazards analysis confirmed hypernatremia as an independent predictor of mortality after adjustment for age, sex, and renal function (hazard ratio 2.4, p < 0.001). Among patients with severe hypernatremia (n = 31), mortality remained high (42%), with most patients presenting with altered mental status and requiring ICU admission. Sodium correction within the first 24 h was modest in the majority. Hypernatremia was relatively uncommon among hospitalized ED patients but was strongly associated with increased mortality. Severe hypernatremia represents a high-risk condition characterized by critical illness and limited early sodium correction. These findings highlight the need for improved recognition and management strategies for hypernatremia in the emergency department.

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.

Backgrounds: Few studies have reported the prevalence and characteristics of hypouricemia in the emergency department (ED). We investigated the prevalence and characteristics of hypouricemia in the ED of a university‐affiliated hospital in Japan.Methods: This is a retrospective cross‐sectional single‐center study. All adult patients (18 years old or older) who had their serum uric acid (SUA) measured at the ED between 2011 and 2021 were included. Information collected included age, sex, SUA, and serum creatinine. Hypouricemia was defined as an SUA level ≦2.0 mg/dL.Results: A total of 10,551 patients were included in the study. Fifty‐one percent were male. The median SUA levels were significantly higher in men than in women (6.0 [4.8−7.4] vs. 4.7 [3.7−6.1], p < 0.001). The prevalence of hypouricemia was higher in women than in men (2.0% vs. 0.9%, p < 0.001). A possible cause of hypouricemia was identified in 88 patients. Malignancy and diabetes were the major possible cause of hypouricemia (p < 0.001).Conclusion: The distribution of SUA levels and prevalence of hypouricemia differed significantly by sex and age in the ED. Malignancy was the leading cause of hypouricemia in the ED.

Background Hyponatremia is one of the most common electrolyte abnormalities. Overcorrection of severe hyponatremia can result in serious neurological complications such as osmotic demyelination syndrome, but the incidence and risk factors of overcorrection and osmotic demyelination have not been thoroughly investigated. Methods This is a single-center retrospective cohort study of 50 patients admitted through the emergency department with initial serum sodium (serum Na) < 125 mEq/L between January 2015 and December 2017. Incidence and risk factors of overcorrection and osmotic demyelination were examined. Overcorrection was defined as an increase in serum sodium concentration > 10 mEq/L at 24 h and/or > 18 mEq/L at 48 h, respectively. Results Six patients (12%) and one patient (2%) had overcorrection at 24 h and 48 h, respectively. A total of 5 (10%) patients had a brain MRI completed after overcorrection, and no patient showed radiologic evidence of osmotic demyelination. Symptomatic hyponatremia at presentation and 3% saline use were associated with the risk of overcorrection in univariable analysis (p < 0.001; p = 0.006, respectively). Conclusions Among patients admitted with severe hyponatremia, overcorrection occurred in 14%. Symptomatic hyponatremia at presentation and 3% saline use were associated with the risk of overcorrection.

Background and Aims: Hypokalemia is one of the most common problems in the emergency department (ED). Severe hypokalemia, defined as a serum potassium level ≤2.5 mEq/L, is a relatively uncommon electrolyte disorder, and few studies have reported its prevalence, etiology, symptoms, and management in the ED. Therefore, we aimed to investigate them in this study.Methods: This retrospective single‐center study included adult patients whose serum potassium levels were measured in the ED between 2012 and 2019. Data including age, sex, serum potassium levels, and serum creatinine levels were collected from the electronic medical records.Results: The serum potassium levels of 21,616 adult patients were measured. The median age of these patients was 73 years (range: 57–83 years), and 38% were men. The prevalence of severe hypokalemia was 0.4%. The most common symptom of symptomatic severe hypokalemia was weakness (p = 0.001). Malnutrition, use of Japanese herbal medicine, and use of diuretics were the main causes of severe hypokalemia. Sixty‐one patients (70%) underwent electrocardiography. Fifty‐nine patients (68%) received treatment for severe hypokalemia within one day of the visit.Conclusion: The management of severe hypokalemia in the ED may be suboptimal. Emergency physicians should be vigilant to avoid missing hypokalemia.

Background: Hyperkalemia is an electrolyte disorder frequently encountered in the emergency department. There are few studies on seasonal variation in the prevalence of hyperkalemia. The aim of this study was to investigate the seasonal changes in the prevalence of hyperkalemia in the emergency department. Materials and Methods: We retrospectively reviewed a total of 24,085 patients presented to the emergency department between January 2012 and December 2020. Age, gender, serum potassium level, and serum creatinine level were recorded. The definition used for hyperkalemia was a serum potassium level of ≥ 5.5 mEq/L. Renal function was divided into two categories: preserved (eGFR ≥ 60 mL/min/1.73 m²) or reduced (eGFR < 60 mL/min/1.73 m²). Results: The prevalence of hyperkalemia was 2.1% in patients with preserved renal function and was 11.9% in patients with reduced renal function (p < 0.001). The prevalence of hyperkalemia was highest in winter, followed by spring, autumn, and summer in patients with preserved renal function (p < 0.001) and those with reduced renal function (p < 0.001). There was a linear correlation between monthly weather temperature and the prevalence of hyperkalemia in patients with preserved renal function (r = −0.392; p < 0.001) and those with reduced renal function (r = −0.487; p < 0.001). Conclusions: we found that the prevalence of hyperkalemia was significantly higher in winter for both patients with preserved renal function and those with reduced renal function.

Background: The number of new dialysis patients, particularly among the elderly population, has been globally increasing. In Japan, patients aged ≥65 years and ≥75 years comprised 72% and 45% of patients on dialysis in 2018, respectively. Few studies have reported seasonal variations in the initiation of dialysis. We investigated the seasonal prevalence of the emergent hemodialysis initiation in the elderly.Methods: We reviewed 479 elderly patients who initiated hemodialysis between January 2006 and December 2018. Early elderly patients were defined as patients aged between 65 and 74 years, and late elderly patients were defined as those aged ≥75 years. Emergent hemodialysis initiation was defined as initiation with a temporary vascular catheter without elective permanent vascular access or unplanned hemodialysis initiation due to patients requiring critical care regardless of elective permanent vascular access. The information collected included age, sex, and details of the initiation of hemodialysis.Results: The early elderly group consisted of 199 patients, and the late elderly group consisted of 279 patients. In the late elderly group, hemodialysis initiation was most frequent in winter, followed by spring, autumn, and summer (p = 0.018). Moreover, emergent hemodialysis initiation was most frequent in winter, followed by spring, autumn, and summer (p = 0.009). Emergent hemodialysis initiation due to fluid overload was most frequent in winter, followed by autumn, spring, and summer (p < 0.001). Among late elderly patients who initiated hemodialysis, 78% did not have permanent hemodialysis access at the time of the initiation of hemodialysis.Conclusion: In the late elderly group, hemodialysis initiation and emergent hemodialysis initiation were significantly more frequent in the winter than in the remaining seasons. In addition, emergent hemodialysis initiation due to fluid overload was most frequent in winter in the late elderly group.