Transient hyperammonemia of the newborn: a vascular complication of prematurity?

Transient hyperammonemia of the newborn is an overwhelming disease manifested by hyperammonemic coma in ill premature infants. A summary of evidence is presented supporting the hypothesis that this syndrome is a vascular complication caused by shunting of blood away from the portal circulation of the liver into the systemic circulation with subsequent lack of ammonia removal. Alternative, nontraditional approaches of investigation and therapy targeting the hepatic portal circulation should be explored in patients with transient hyperammonemia of the newborn.