Long-term outcome of profound hyponatremia: a prospective 12 months follow-up study

Hyponatremia is the most common electrolyte abnormality in hospitalized patients and given its impact on mortality and morbidity, a relevant medical condition. Nevertheless, little is known about factors influencing long-term outcome.; This is a prospective observational 12-month follow-up study of patients with profound hyponatremia (≤125 mmol/L) admitted to the emergency department of two tertiary care centers between 2011 and 2013. We analyzed the predictive value of clinical and laboratory parameters regarding the following outcomes: 1-year mortality, rehospitalization and recurrent profound hyponatremia.; Median (IQR) initial serum sodium (s-sodium) level of 281 included patients was 120 mmol/L (116-123). During the follow-up period, 58 (20.6%) patients died. The majority (56.2%) were rehospitalized at least once. Recurrent hyponatremia was observed in 42.7%, being profound in 16%. Underlying comorbidities, assessed by the Charlson Comorbidity Index, predicted 1-year mortality (odds ratio (OR) 1.43, 95% confidence interval (CI) 1.25-1.64, P  120 mmol/L (14.8% and 27.8%, P  120 mmol/L.; Hyponatremia is associated with a substantial 1-year mortality, recurrence and rehospitalization rate. The positive correlation of s-sodium and mortality emphasizes the importance of the underlying disease, which determines the outcome besides hyponatremia itself.