Salt depletion and dehydration in hypertensive preterm infants.

Three preterm infants presented with both severe or moderate arterial hypertension and dehydration due to increased water and sodium urinary excretion. In patient 1, water and sodium wasting were extremely severe and peaked at 575 ml/kg per day and 73 mEq/kg per day, respectively. In all infants, urinary water and sodium excretion dramatically decreased when hypertension resolved. The overall clinical data suggest a pressure natriuresis phenomenon.