Clinical significance of arginase after liver transplantation

Liver graft function after transplantation is dependent on ischemia-reperfusion injury, toxicity of drugs (immunosuppression, antibiotics and other) and transplant rejection. Although routinely monitored with enzymatic tests (AST, ALT, GGT, ALP), bilirubin and coagulation parameters, differentiation between these pathologies is hardly possible without liver biopsy. Arginase (3.5.3.1) mostly exists in the liver and in trace amounts in extra-hepatic tissue. Thus, we hypothesized that activity of arginase could be a more specific test of liver function. Sera of 32 liver transplant recipients were tested for AST, ALT, ATIII, bilirubin and arginase. Samples were obtained daily in first 2 weeks after LTx and weekly afterwards. Correlation of arginase activity with other liver function markers was calculated. Serum arginase peaked at day 1 post LTx (mean 64,6+/-91 IU/L), and decreased more rapidly than other tests if good liver function was observed. The values showed strong and significant correlation with AST and ALT activities (Pearsons R 0,65 and 0,47 respectively). We conclude that activity of arginase in the serum is an exact test of liver function.