Treatment (Rx) and Outcomes of Profound Hyponatremia

Background: A thirty-year controversy on how severe, symptomatic hyponatremia should be treated gave way to consensus guidelines published in 2013 and 2014 recommending correction limits of 8 to 10 mmol/L/day to avoid osmotic demyelination syndrome (ODS) in high-risk patients. Recently, guidelines have been challenged by studies suggesting that ODS is “exceedingly rare” and unrelated to rate of correction (NEJM Evid, 2023;2:EVIDe2300014). A multi-center study to update data supporting current guidelines is in progress. Preliminary data from one of the study sites are presented here. Methods: We reviewed medical records of all 23 patients admitted to four hospitals between 2015 and 2023 with serum sodium (SNa) ≤105 mmol/L and compared Rx and outcomes to a 1987 study of patients with SNa ≤105 mmol/L from the same region (Ann Int Med 1987;107:656). Results: In the current study, 3 of 7 patients whose largest 24 hour increase in SNa (dSNa) was ≥12 mmol/L developed ODS -- 1 with MRI-documented central pontine myelinolysis (CPM) and 2 with CPM and extrapontine myelinolysis (EPM). Two of the patients with ODS developed severe neurological complications and one had only mild dysarthria. Median dSNa for all 23 patients was 10 mmol/L (IQR = 5); 12 were given DDAVP & D5W to re-lower SNa because of dSNa ≥8 mmol/L. In 11 of 11 patients Rx'd. with proactive DDAVP and 3% NaCl ("DDAVP clamp"), dSNa was ≤10 mmol/L; in 9 of 11, dSNa was ≤ 8 mmol/L. In the 1987 study, the hourly rate of correction to reach a SNa ≥ 120 mmol/L was nearly twice as fast as in the current study. Conclusion: Preliminary data suggest that ODS is not exceedingly rare in patients with SNa ≤105 mmol/L who are corrected by ≥12 mmol/L/24h. ODS may be less common now than it was in the 1980s because of changes in practice patterns. Additional data from other study sites will be needed to validate these conclusions.