Use of Monitoring Gamma-Glutamyl Transpeptidase Levels After Liver Transplant: A Longitudinal Retrospective Analysis of a Single-Center's Experience

Objectives: Recently, gamma-glutamyl transpeptidase has garnered increased attention as a diagnostic tool in the early identification of liver disease. However, its value in liver transplant is largely unknown, as the disease processes leading to abnormal gamma-glutamyl transpeptidase levels and the expected temporal trends in gamma-glutamyl transpeptidase levels during the period after liver transplant remain unclear. Materials and Methods: Between January 2010 and August 2013, consecutive patients who underwent liver transplant at Vancouver General Hospital (Vancouver, Canada) were assessed longitudinally up to 1 year after liver transplant. A gamma-glutamyl transpeptidase event was defined as 2 abnormal gamma-glutamyl transpeptidase values (exceeding sex-specific limits of normal, at 55 U/L for female and 80 U/L for male patients) >= 1 week apart. Results: Our study included 147 liver transplant recipients. The median gamma-glutamyl transpeptidase level on day 1 after liver transplant was 73 U/L, which peaked to 435 U/L during the first month after liver transplant and returned to within normal parameters by 1 year. In total, there were 282 gamma-glutamyl transpeptidase events, with biliary complications (22%), acute rejection (16%), and hepatitis C virus recurrence (10%) being the most common causes. In 39% of events, no cause was identified. When attempting to identify a disease-associated event, if gamma-glutamyl transpeptidase was the initial liver biochemistry test to double in value, it had 42% sensitivity and 40% specificity. Comparatively, if gamma-glutamyl transpeptidase was the initial liver biochemistry test to become abnormal, it had 3% sensitivity and 93% specificity. Conclusions: Although gamma-glutamyl transpeptidase almost universally becomes abnormal after liver transplant, a specific pathologic cause was not commonly identified. Interpreting the characteristics of gamma-glutamyl transpeptidase elevation has limited use for identifying the underlying reason for its elevation.