Our findings indicate that serum amino acid changes after OLT are complex and influenced by multiple factors including sepsis and use of parenteral hyperalimentation with exogenous amino acids. Additional factors which may influence the rate of normalization of amino acids after OLT include the presence of malnutrition (frequently observed before OLT) and the extent of pretransplant portal-systemic shunting. Our results demonstrate that the presence of septic complications and the use of CPN are important determinants of the postoperative levels of several amino acids, including the BCAA/AAA ratio. Our logistic regression model using the BCAA/AAA ratio predicted the occurrence of sepsis after OLT 77% of the time. Prospective assessment and validation of this model is under way.