Metabolic Issues in Liver Transplantation

Abstract

Patients who undergo orthotopic liver transplantation (OLT), almost by definition, have end-stage liver disease. One cannot examine the metabolic changes observed during OLT without insight into the profound effects of preexisting liver dysfunction. Because the liver plays a central role in regulation of whole-body metabolism, its disease leads to major alterations in glucose metabolism. Most patients presenting for OLT have chronic liver disease which has gradually progressed to the point where replacement surgery is indicated. The endocrine and metabolic changes associated with chronic cirrhosis are well described. A small subset of patients presents for OLT with fulminant liver failure which may or may not have been preceded by chronic liver disease. Evidence describing metabolic alterations of patients with fulminant disease, because of its unstable nature, is much less complete than that for patients with chronic disease. Many of the underlying endocrine and metabolic alterations are exacerbated by the OLT procedure itself. After OLT, full normalization of glucose metabolism is delayed and corrects in stages. Certain primary inherited diseases (‘‘inborn errors’’) of metabolism, which can be corrected by OLT, present unique issues that are beyond the scope of this review. Patients with end-stage liver disease exhibit disturbances in lipid, amino acid, and protein metabolism; and also poor clearance of drugs whose elimination or biotransformation depends on hepatic function. However, these subjects are also outside of the scope of the present review. This review focuses on the intertwined derangements of glucose metabolism, acid-base balance, and serum electrolyte concentrations that appear in patients before OLT, then describes changes which occur intraoperatively and persist in the postoperative setting. The endocrine environment that in part mediates the metabolic response is presented first.