Drug-Induced Hyponatremia as a Cause of Emergency Department Attendance

Background: Hyponatremia is one of the most common electrolyte disturbances in emergency departments. This study aimed to describe the characteristics of patients presenting with drug-induced hyponatremia and analyse factors associated with 30-day revisits. Methods: Retrospective observational study including adult patients who attended the emergency department for drug-induced hyponatremia between 2020 and 2024. Results: 141 patients were analysed (mean age 80.5 years; 78% women). Thiazide diuretics were the most frequently implicated pharmacological class (50.3%). In univariable analyses, polypharmacy, dementia, and treatment changes at discharge were associated with a higher risk of revisit for hyponatremia. In the multivariable model, only polypharmacy remained significantly associated with 30-day revisits. Conclusions: Thiazide diuretics were the leading drug-related cause of hyponatremia in the emergency setting. Polypharmacy was identified as an independent factor associated with increased revisit risk, underscoring the need for systematic medication review and close clinical follow-up after hospital discharge.