Inappropriate antidiuretic hormone secretion in an infant with severe pneumonia.

A 6-week-old boy with severe pneumonia developed hyponatremia as a result of the syndrome of inapropriate antidiuretic hormone secretion (SIADH). Cerebral edema and seizures occurred after administration of fluids and diuretics. Fluid restriction and resolution of the pneumonia corrected the severe electrolyte imbalance. The possibility of SIADH should be considered in cases of severe and resistant pneumonia in infancy.