Bilateral pneumonia and inappropriate secretion of antidiuretic hormone in a premature infant.

A 6-week-old infant born prematurely had severe hyponatremia and other features of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). This disturbance was believed to be secondary to extensive bilateral pneumonia with collapse of the right upper lobe. Although this association has been recognized in adults, this is the first report of its occurrence in an infant. SIADH must be considered in the differential diagnosis of hyponatremia in association with pneumonia in an infant.