Acetaminophen metabolism after liver resection: A prospective case-control study

Background: The effect of liver resection on acetaminophen metabolism and whether it is affected by residual liver volume is poorly understood. Methods: We investigated the effects of liver resection on acetaminophen metabolism in a single centre, prospective observational, case-control study of inpatients. Patients undergoing liver resection were administered therapeutic post-operative acetaminophen. Glutathione and urinary acetaminophen metabolites were measured over the first three post-operative days and compared between patients with low (Group A) and high (Group B) residual liver volume. Results: 41 patients (41% female, median age 62 [IQR 53-72] years) were included. Mean urinary cysteine levels increased significantly from post-operative day 1 to 2 (578.0 mg/day 95% CI 478.9-677.1 vs. 775.4 mg/day, 95% CI 625.7-925.1; p = 0.03). Group A (n = 11) had significantly higher median levels of cysteine (day 1, 464.3 mg/day [IQR 355.6-582.0]; day 3, 717.6 mg/day [IQR 423.5-1104.0]) compared to Group B (n = 11): day 1, 545.4 mg/day (IQR 346.9-843.5); day 3, 508.1 mg/day (IQR 390.8-788.4; p = 0.048). No significant difference was observed in glutathione or 5-oxoproline levels between the groups. Conclusion: Low residual liver volume results in altered acetaminophen metabolism, however, no evidence of glutathione deficiency was observed. Therapeutic acetaminophen is safe after major liver resection provided liver function is adequate. Crown Copyright (c) 2015 Published by Elsevier Ltd on behalf of Editrice Gastroenterologica Italiana S.r.l. All rights reserved.