The outcome of hyponatremia in a general hospital population

Abstract

To determine the prognosis of hyponatremia in an unselected population, we collected clinical and laboratory data and determined the outcome of hospitalization for all hyponatremic patients in a general hospital over a three month period. Of the 78 patients studied, 36 (46%) had CNS symptoms while 42 (54%) were asymptomatic. Using a diagnostic algorithm we classified the patients with CNS symptoms into two groups: those with CNS symptoms due to hyponatremia (11 patients) and those with CNS symptoms caused by other factors (25 patients). Twenty-one patients (27%) died during the study. The highest mortality (64%) was in patients with CNS symptoms related to factors other than hyponatremia. Patients with CNS symptoms due to hyponatremia had a mortality rate (9%) similar to that of patients without CNS symptoms (10%). These findings suggest that the relationship between hyponatremia and outcome is probably not causal. Rather, hyponatremia appears to be a marker for severe underlying disease that carries a poor prognosis.