[Functional disorder of the hypothalamic osmoreceptor as the cause of excessive hypernatremia in a girl with absence epilepsy].

BACKGROUND

Chronic hypernatremia is a rare disorder in childhood and normally results from impairment of the water homeostasis. In some cases, chronic hypernatremia is caused by decreased intake of water based on impaired thirst perception.

METHODS

We report a girl with microcephaly, partial agenesis of the corpus callosum, mild midface hypoplasia and absence seizures, who presented with severe hypernatremia (serum sodium concentration 189 mmol/l). Though serum osmolality was increased up to 382 mOsm/kg, the girl showed no signs of thirst. After normalization by intravenous fluid therapy, serum osmolality and serum sodium concentration remained in the normal range with an oral water intake of at least 1500 ml/d. Polyuria was never present, the ability to concentrate urine was preserved.

CONCLUSIONS

In summary, we speculate that the chronic hypernatremia in our patient is caused by a selective hypothalamic osmoreceptor dysfunction associated with mild dysplasia of the midline structures. Only very few similar cases have been documented in the literature.