Adipsic hypernatremia in two sisters
G. Radetti, F. Rizza, G. Mengarda and K. Pittschieler
Department of Pediatrics, Regional Hospital of Bolzano, Italy.
We describe two sisters with chronic hypernatremia, lack of thirst, and
inappropriate osmoregulated vasopressin secretion. Only one sister, who
presented with microcephaly and developmental delay, showed signs of
dysplasia of the midline structures (ie, septum pellucidum and corpus
callosum) and a large intracranial cyst. Neither sister showed any signs of
thirst, even when osmolality exceeded 337 mmol/kg. In both patients, the
vasopressin secretion did not respond to either osmotic or nonosmotic
stimuli or was suppressed by a water load. Plasma osmolality values
returned to normal after treatment with forced hydration and a vasopressin
analogue, desamino-D-arginine vasopressin. These findings indicate a severe
defect in the hypothalamic osmoreceptors that control thirst and
vasopressin secretion. To our knowledge, this is the first report of such a
disorder in two sisters.
