Holoprosencephaly: a case presenting with adipsic hypernatremia.

An 11-month-old female infant presented with mild fever, hypernatremia, microcephaly, and growth and developmental delay. No sign of thirst was noted in this infant even when the osmolality was over 318 mOsm/kg. Magnetic resonance imaging demonstrated a lobar type holoprosencephaly. Plasma osmolality levels returned to normal after forced hydration and administration of a vasopressin analogue. These findings suggested holoprosencephaly may be associated with a defect in the hypothalamic osmoreceptors that control thirst and vasopressin secretion.