Overcorrection of severe hyponatremia, osmotic demyelination syndrome, and mortality: insights from two Brazilian centers

Severe hyponatremia (sodium ≤ 120 mmol/L) poses significant clinical risks, including encephalopathy and seizures, but inadvertent rapid correction may cause osmotic demyelination syndrome (ODS). Current guidelines recommend limiting sodium correction to ≤8 mmol/L per 24 hours to minimize ODS risk. However, recent studies suggest that overcorrection may not directly contribute to mortality and could even be associated with improved outcomes.

This retrospective cohort study included 362 patients with severe hyponatremia admitted to two Brazilian tertiary hospitals. Overcorrection was defined as a serum sodium increase >8 mmol/L in 24 hours or >18 mmol/L in 48 hours. Multivariate logistic regression and propensity score-weighted analyses were used to identify predictors and outcomes associated with overcorrection.

Overcorrection occurred in 38.7% of patients whereas ODS occurred in only one patient (0.28%). Independent predictors of overcorrection included younger age, lower admission sodium levels, and higher volumes of 0.9% NaCl administered in the emergency room; cancer diagnosis and furosemide use were protective factors. Overcorrection was associated with lower in-hospital mortality and shorter hospital stays, even in propensity score-weighted multivariate analyses. However, a detailed review of mortality cases revealed no direct causal link between the rate of sodium correction and death.

Overcorrection of severe hyponatremia was common and associated with better clinical outcomes, without a significant increase in the risk of ODS. However, given the observational nature of this association, randomized controlled trials are needed before the current guidelines for correction rate can be reconsidered.