Background: Hyponatremia is the most common electrolytic disturbance among inpatients. It is associated with poor outcomes in frail older patients, even for mild disturbances. Prevalence increases with age, and the commonest cause is the Syndrome of Inappropriate Antidiuresis. We assessed observationally the practice patterns toward diagnosis and treatment of euvolemic hyponatremia according to severity in a geriatric setting.

Methods: All euvolemic hyponatremic patients admitted to acute geriatric wards in 2023 were retrospectively included. Demographic, biological and clinical characteristics, geriatric syndromes and outcomes were extracted from medical records. Mild (134-130mmol/L), moderate (129-125 mmol/L) and profound (<125 mmol/L) groups were compared. Regression analyses between hyponatremia and clinical outcomes (delirium or falls incidence, 6-month and 1-year mortality and readmission) were realised.

Results: The 130 euvolemic hyponatremic patients included had a mean age of 87 years, a mean Cumulative Illness Rating Scale of 17 points and 96.5% had low physical performance. Hyponatremia was mentioned in 32.3% of medical files. Forty-two percent had urine spot tests performed in the first 48h. Fluid restriction was the commonest treatment but was implemented in 26.2% of cases. Significant differences were found across severity groups (p<0.001). One third of patients remained hyponatremic at discharge, especially profound cases (77.8%, p<0.05). We found no independent association between hyponatremia severity and outcomes.

Conclusion: Hyponatremia is poorly considered and investigated in acute geriatric wards. Mild and moderate hyponatremia are unfrequently treated despite existing guideline-recommended therapies. Clinicians are encouraged to exhaustively investigate hyponatremia in geriatric patients, even in mild cases.