Syndrome of inappropriate antidiuretic hormone secretion refractory to treatment in a newborn with alobar holoprosencephaly.

Alobar holoprosencephaly (AHP) is a serious malformation of the central nervous system characterized by complete failure of cleavage of the prosencephalon resulting in fusion of the cerebral hemispheres and a massive single ventricular midline fluid collection. Secretion of inappropriate antidiuretic hormone syndrome (SIADH) is a disorder of fluid-electrolyte balance caused by the inability to suppress the secretion of antidiuretic hormone (ADH) resulting in the development of hyponatremia. Coexistence of both of these entities has not been described in the literature. We report a newborn infant with AHP who had resistant SIADH refractory to treatment, to draw attention to the coexistence of these entities and to contribute to the literature with the management of this challenging condition.