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Abstract: SA-PO734

Urea for the Treatment of Hyponatremia: A Two-Center Experience

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical


  • Pelouto, Anissa, Erasmus MC, Rotterdam, Zuid-Holland, Netherlands
  • Monnerat, Sophie, Universitatsspital Basel, Basel, Switzerland
  • Zandbergen, Adrienne Anne Marie, Erasmus MC, Rotterdam, Zuid-Holland, Netherlands
  • Refardt, Julie, Universitatsspital Basel, Basel, Switzerland
  • Christ-Crain, Mirjam, Universitatsspital Basel, Basel, Switzerland
  • Hoorn, Ewout J., Erasmus MC, Rotterdam, Zuid-Holland, Netherlands

Oral urea is an effective treatment for hyponatremia, especially in patients with the syndrome of inappropriate antidiuresis (SIAD). However, data are limited and no predictors for treatment response have been identified. Here, we report our two center experience on efficacy, safety and tolerability of oral urea to correct hyponatremia.


Retrospective study including hospitalized patients at the Erasmus Medical Center, The Netherlands and University Hospital Basel, Switzerland who received oral urea for hyponatremia (plasma sodium (pNa) <135 mmol/l) between August 2018 and September 2022. The primary outcome was the rise in pNa until discontinuation of urea and/or discharge. The secondary outcomes included the risk of overcorrection (rise in pNa >10 mmol/l in 24h) and urea discontinuation due to side effects. Linear regression analyses were performed to identify predictors for pNa rise.


In 138 patients (median age 69, 53% males, 92% SIAD) 159 urea treatment episodes (median dose 30 g/d) were identified. Concomitant fluid restriction (median 1L/24h) was prescribed in 88%. Under urea, pNa rose from 127 mmol/L (IQR 123–129) to 134 mmol/L (IQR 131–136) in 4 days (IQR 2–7) and pNa normalization was achieved in 47% of the cases. Higher baseline pNa and more liberal fluid intake were associated with a lower pNa rise (-0.7 mmol/L, 95%CI -0.8 to -0.6 and -0.4 mmol/L, 95%CI -0.6 to -0.2, respectively). In contrast, longer treatment duration and higher estimated glomerular filtration rate (eGFR) were associated with a greater pNa rise (0.3 mmol/L, 95%CI 0.1 to 0.4 and 0.2 mmol/L, 95%CI 0.1 to 0.4, respectively). Patients who reached normalization were treated significantly longer than those who did not (median 6 vs 3 days). Overcorrection occurred in 6 patients (4%, rise 13 ± 2 mmol/L in 24h). Urea was discontinued in 12 patients (9%) due to poor palatability and/or gastro-intestinal symptoms. No treatment-related serious adverse events, including osmotic demyelination syndrome occurred.


In this largest cohort reported to date, oral urea effectively corrected hyponatremia with a relatively low rate of overcorrection and side-effects. Higher baseline pNa and more liberal fluid intake were associated with a lower pNa rise, whereas longer treatment and higher eGFR were associated with a greater pNa rise.