Range of Normal Serum Aminotransferase Levels in Liver Transplant Recipients

Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are used to monitor liver transplant recipients (LTR) but the reference range and context of its use is not well defined. We aimed to determine the healthy ranges in LTR without chronic liver disease. Methods. One hundred and three LTR without chronic liver disease based on serology, transient elastography with controlled attenuated parameter, and ultrasound were included. A healthy range of aminotransferases was set to 95th percentile. An updated normal aminotransferase range was used to detect recurrence in post-liver transplantation (LT) with hepatitis C virus (HCV) and nonalcoholic fatty liver disease (NAFLD). Results. The normal ALT and AST range was 0 to 57 and 0 to 54 IU/L, respectively, in LTR and was not affected by age, sex, obesity, or choice of immunosuppressant. The diagnostic performance of serum ALT and AST to detect recurrence of NAFLD by a controlled attenuated parameter was poor with area under the receiver operating characteristic curve of 0.573 (95% confidence interval 0.493, 0.655; P = .08) and 0.537 (0.456, 0.618; P = .4), respectively. In contrast, the diagnostic performance of ALT and AST to detect recurrence of HCV after LT was 0.906 (0.868, 0.944; P < .001) and 0.925 (0.890, 0.959; P < .001), respectively. Conclusion. The updated aminotransferase range in LTR is higher than the general population and accurate for detecting recurrent HCV, but not NAFLD.