Since its introduction into clinical practice,
parenteral nutrition has revolutionized the care of premature neonates. Serum
transaminase and
bilirubin levels are commonly elevated in infants on
parenteral nutrition, but their normalization is typical in the setting of short-term administration of
parenteral nutrition uncomplicated by
sepsis. Premature infants who require long-term
parenteral nutrition are, however, at severe risk for developing life-threatening hepatic complications. These complications include
cirrhosis, liver failure, and the concomitant risks of
sepsis, coagulopathy and death. Premature infants and those with
short-bowel syndrome are most susceptible to these morbid outcomes. Although it has been more than a quarter of a century since
parenteral nutrition was first introduced and its association with hepatic complications described, the precise etiology of
parenteral nutrition associated
cholestasis (PNAC) remains a mystery; however, our understanding of the molecular components that contribute to PNAC has improved substantially. In this Review, we summarize the fundamentals of PNAC, describe animal models of the disease, review the hepatic
bile acid transporters that are crucial for
bile acid homeostasis, and define the roles that
endotoxin, genetics, and the components of
parenteral nutrition are likely to have in the molecular pathogenesis of this life-threatening condition.