Hepatic Function Measured by Amino Acid Utility Index (AAUI) and Surgical Stress

Surgical tissue injury accelerates the transfer of amino acids from skeletal muscle to the liver for protein synthesis required for the maintenance of immunocompetence and wound healing. For clinical measurement of this function, we developed a new indicator, the amino acid utility index (AAUI), by using the rate of muscle release of amino acid (m-RR) and the rate of central plasma clearance of amino acids (CPCR-AA) reported by Clowes et al in 1984. They are the indexes of muscle proteolysis and whole body protein turnover, and AAUI is expressed by the formula. AAUI (ml/µmol)=CPCR-AA/m-RR Thirty patients were studied before and after recovery from surgical stress and were divided into four groups. In group 1, the control, seven patients with normal liver function had received esophagectomy. In group 2, nine patients had received hepatectomy of one segmentectomy or smaller resection. In group 3, ten patients had received hepatectomy of 2 or 3 segmentecotmies. In group 4, four patients had died of liver failure after hepatecotmy. According to the degree of surgical stress, the values of m-RR as well as CPCR-AA were increased in each group on the 2nd post-operative day. But the values of AAUI were 7.8 ± 0.9 (group 1), 8.2 ± 2.1 (group 2), 4.7 ± 2.1 (group 3) and in group 4 marked decrease below 3.0 was noted during the immediate postoperative period. This finding suggests that AAUI can be a clinical prognostic index for estimating hepatic function without the influence of surgical stress.