1513: Comparison of Urea vs Fludrocortisone in Correction of Hyponatremia in Neurocritical Care Patients

Introduction: Hyponatremia is a common electrolyte disturbance seen in patients with acute brain injury. It is associated with increased morbidity and length of hospitalization in these patients due to development or worsening of cerebral edema and seizures. Urea has been used in SIADH but not specifically for patients with acute neurological injury. Our aim was to compare the efficacy of urea vs fludrocortisone in correction of serum sodium (sNa) in neurocritically ill patients receiving sodium chloride (NaCl) tablets. Methods: Retrospective study of adults admitted to neurocritical care unit with hyponatremia who received NaCl tablets in combination with fludrocortisone or urea between January & June of 2024 & 2025. Exclusion: (1) received both fludrocortisone & urea, (2) at target sNa upon initiation of treatment, (3) only one dose of therapy received (4) trauma patients. Primary outcome: 24-hour change in sNa. Secondary outcomes: (1) time to goal sNa (2) whether hypertonic saline (HTS) was used to achieve goal Results: 114 patients were identified. After exclusion, final analysis: 52 vs 48 in the fludrocortisone vs urea groups respectively. Characteristics: median age 60 & 46% female. Primary diagnoses: subarachnoid hemorrhage (21%), intracerebral hemorrhage (20%), acute ischemic stroke (19%). Median total daily dose (TDD) of NaCl was 8 GM in fludrocortisone vs 4 GM in urea group. The median initial TDD was 200 mcg fludrocortisone and 30 mg urea. Median target SNa was 140 mEq/L in both groups. Median 24-hr change in sNa: 2[1-4] vs 3[1-4] mEq/L, (p 0.44). Median time to goal: 26.8 [23 – 69] vs 48.8 [43- 72] hours (p 0.04) & HTS use was 26.5% vs13.6% (p 0.12) in fludrocortisone vs urea cohort. Conclusions: Hyponatremia in brain injury is due to syndrome of inappropriate ADH secretion (SIADH) or cerebral salt wasting (CSW). While HTS is used for acute cerebral edema to prevent herniation, other modalities like enteral NaCl and mineralocorticoid are widely used to achieve sNa goal. Urea is an osmolar agent with reflection co-efficient 0.59 that reduces interstitial edema and promotes renal water excretion. It is cheaper than fludrocortisone. Our data shows similar efficacy of urea to fludrocortisone in hyponatremia in acute brain injury. Larger trials are required to assess impact on functional outcomes.