Introduction:
Hypernatraemia has serious complications such as brain injury, brain oedema and seizure. In this study, the incidence among children hospitalized hypernatremia, causes, development time, clinical features, and morbidity, and aimed to reveal the effect on mortality.

Material and Methods:
In this retrospective study, clinical and laboratory data from patients with hypernatremic were recorded. The study period was 33 months. The groups were separated into two groups; group I: Hypernatremia was present at hospital admission, group II: Hypernatremia was acquared after the hospitalization.

Results:
Overall incidence of hypernatraemia was 1.3% of all hospitalised children. While 42% of patients were from group I, 58% of patients had acquired hypernatremia during hospital stay. In group I, 61% of patients had infections on hospital admission. The most common cause of hypernatraemia in group II was neurological disorders (53%). The mortality rate was 30.5% (11/36) in patients with hypernatraemia on admission, 67.3% (33/49) in those with hospital-acquired hypernatraemia (P<0.05; significantly greater than for those with hypernatraemia on admission), and 51.7% (44/85) overall. Mean serum sodium level was higher in non-survivors than in survivors (161.7±8.3 mg/dL vs. 160±7.4 mg/dL), but the difference was not statistically significant. Similarly, there was no significant difference in peak serum sodium levels in survivors versus non-survivors, P>0.05.

Conclusions:
Hypernatraemia in pediatric age is associated with mortality and morbidity, and should be closely monitored in pediatric patients hospitalized for any reason in order to prevent complication.