The changing pattern of hypernatremia in hospitalized children

Past studies have revealed that hypernatremia occurs primarily in infants with diarrheal dehydration. With improved infant feeding practices and the advent of pediatric critical care medicine, the pattern of hypernatremia in children has likely changed. The purpose of this study was to evaluate the current pattern of hypernatremia in hospitalized children.

Medical records were reviewed for 68 patients admitted to a large urban children's hospital during a 3-year period, all with a serum sodium greater than 150 mEq/L. The etiologies, predisposing factors, and morbidity and mortality associated with hypernatremia were evaluated.

The average patient age was 3.9 years (range, 1 day to 19. 7 years), and the peak serum sodium concentration was 159 mEq/L (range, 151-184 mEq/L). Hypernatremia was hospital acquired in 60% of children. The majority of children (71%) were admitted for reasons other than hypernatremia. In 76% of the patients, inadequate fluid intake was the main cause of hypernatremia. Gastroenteritis contributed to the hypernatremia in only 20% (14 out of 68) of children. Eleven of these were infants <1 year of age with hypernatremia on admission. Eighty-eight percent of patients (60 out of 68) suffered from neurologic impairment, critical illness, chronic disease, or prematurity before developing hypernatremia. The overall mortality was 16%. Patients in whom hypernatremia was not corrected had a significantly higher mortality than those in whom hypernatremia was corrected (4 out of 8 [50%] vs 7 out of 60 [12%]). Peak serum sodium was no different for survivors than nonsurvivors. No deaths were attributable to cerebral edema caused by correction of hypernatremia. Neurologic complications related to hypernatremia occurred in 15% of patients.

Hypernatremia occurs in children of all ages, with the vast majority having significant underlying medical problems. Hypernatremia caused by gastroenteritis in infants has become much less common than previously reported. Hypernatremia is primarily a hospital-acquired disease, produced by the failure to administer sufficient free water to patients unable to care for themselves. Failure to correct hypernatremia may result in a high mortality rate.