#1496 Evaluation of the diagnostic and therapeutic management of hyponatremia in a tertiary hospital: are we doing it right?

Abstract Background and Aims Hyponatremia is a highly prevalent condition among hospitalized patients, associated with increased mortality, prolonged hospital stays and higher healthcare costs. Due to its occurrence in the context of multiple pathologies, a significant number of specialists are involved in its identification and management. Method A retrospective review was conducted of hospitalized patients at La Paz University Hospital in Madrid between January 2021 and November 2022. The review included patients for whom a consultation with the nephrology department was requested to evaluate hyponatremia during their clinical course. Data collected included variables related to the diagnosis of hyponatremia (e.g., serum and urinary osmolality, urinary electrolytes, volume status, medications), as well as its management at presentation, during follow-up by Nephrology, and over the course of one year. Results A total of 90 episodes were analyzed. Of the patients included, 55.6% were males and the mean age was 71.33 years. Half of the patients were taking one or more medications predisposing to hyponatremia, and 50% had recent oncological history. Upon arrival at the emergency department, 54.4% presented with hyponatremia, with a mean sodium (Na) level of 126.22 mmol/L. At the time of diagnosis, only 33.7% had both plasma osmolarity and urinary electrolytes/osmolality measured, although this percentage increased to 80% in patients with Na <120 mmol/L. Immediate treatment was initiated in 61%, with the most common being 0.9% saline solution (37.8%). Among patients with Na <120 mmol/L, 30% did not receive any correctional treatment. Sodium levels were monitored within 24 hours of presentation in the majority of patients (81%). The average waiting time for a Nephrology consultation was 7.64 days (median 3 days), with a mean Na of 125.58 mmol/L. A moderate-to-strong positive correlation was observed between the time until consultation and the time to achieve normonatremia. The most frequent etiology of hyponatremia was SIADH (40%), followed by hypovolemic/diuretic induced (33.3%). Of the 31% of patients who did not achieve normonatremia at discharge, 46.4% died within the first year of follow-up. However, no statistically significant association was found between sodium correction and one-year mortality. Conclusion Establishing an adequate etiological diagnosis of hyponatremia is essential to optimize treatment and improve both the clinical course and hospital outcomes. In our study, the involvement of the Nephrology Department was associated with a timely achievement of normonatremia, highlighting the importance of specialized evaluation in the management of hyponatremia.