Clinical profile of hyponatraemia in critically ill patients: A retrospective study

Introduction: Hyponatraemia is the most common electrolyte disorder affecting hospitalised patients, being more prevalent in the elderly. The objective of this study was to characterise the severity distribution, clinical manifestations, associated comorbidities and the correlation between acute physiology and chronic health evaluation II (APACHE II) score and in-hospital mortality among critically ill adult patients with hyponatraemia. Material and Methods: A retrospective study included patients 18 years and above, admitted to the internal medicine department between January and December 2023 having confirmed hyponatraemia (serum sodium <135 mEq/L). Patients’ demographics and history were recorded from case records from the Medical Records Department of the Institute. APACHE II score was calculated to assess disease severity. Data were entered into a Microsoft Excel sheet and analysed using the Statistical Package for Social Sciences Software. Results: Out of 562 patients admitted during the study, 209 (37.1%) were diagnosed with hyponatraemia. Among them, 127 (60.7%) had mild, 42 (20%) had moderate and 40 (19.1%) had severe hyponatraemia. Nearly half of the patients (45%) were symptomatic, with nausea/vomiting (64%) and altered sensorium (40%) being the most common clinical manifestations. Diabetes mellitus (43%) and hypertension (41.1%) were the most frequently associated comorbidities, with a history of diuretic use in 13.3% of patients. Intensive care unit admission was required in 19.6% and 13.8% required ventilatory support. The APACHE II score ranged from 2 to 44, with higher scores associated with increased mortality. Overall mortality was 9%, with the majority of deaths occurring in patients with APACHE II scores >30. Conclusion: Hyponatraemia is a common electrolyte abnormality among critically ill elderly patients and is frequently associated with neurological symptoms and cardiometabolic comorbidities. Higher APACHE II scores are strongly associated with increased mortality. Routine serum sodium monitoring and early risk stratification using APACHE II scoring in high-risk patients may help in early identification and prevention of adverse outcomes related to hyponatraemia.