Role of liver enzymes in patients with blunt abdominal trauma to diagnose liver injury

The liver is the second most injured organ following blunt abdominal trauma (BAT) after the spleen. Although the computed tomography (CT) scan is considered as the gold standard for diagnosing liver injury in BAT, it may not readily available in all the hospitals. This study was performed to evaluate the role of aspartate transaminase (AST) and alanine transaminase (ALT) in patients with BAT and its significance in predicting the diagnosis and severity of the liver injury.

The study was conducted in Chitwan Medical College Teaching Hospital (CMCTH) from February 2019 to May 2020. It was a prospective observational study. All the patients with BAT were received by on-duty surgical residents in the emergency department. Based on the imaging and operative finding, patients with liver injury and without liver injury were noted with the associated injury. For comparisons of clinical and grading characteristics between the two groups (liver injury and no liver injury), the chi-squared test was used for categorical variables as appropriate, and the Mann-Whitney U test used for quantitative variables (AST and ALT). The comparisons between more than two groups (grade of injury) were performed using the Kruskal-Wallis test. The receiver operating characteristic (ROC) was used to calculate the optimal cut-off value of AST and ALT.

Among the 96 patients admitted with BAT, 38 patients had liver injury and 58 patients had no liver injury. The median length of the intensive care unit (ICU) stay of patients with liver injury was higher than without liver injury. There was a significant difference in the median level of AST and ALT (< 0.001) between patients with liver injury and no liver injury. The area under the ROC curve of AST was 0.89 (95% confidence interval 0.86–0.98) and of ALT was 0.92 (95% confidence interval 0.83–0.97). The area under the curve demonstrated that the test was a good predictor for the identification of liver injury and also the severity of liver enzymes. The cut-off values for the liver injury were 106 U/l and 80 U/l for AST and ALT, respectively. Based on these values, AST ≥ 106 U/l had a sensitivity of 71.7%, a specificity of 90%, a positive predictive value of 86.8%, and a negative predictive value of 77.6%. The corresponding values for ALT ≥ 80 U/l were 77.8%, 94.1%, 92.1%, and 82.8%, respectively.

In conclusion, we report the optimal cut-off value of AST and ALT for liver injury in BAT as ≥ 106 U/l and 80 U/l, respectively. The elevated level of AST and ALT might assist the emergency physicians and surgeons to timely refer the suspected patients with the liver injury to a tertiary center.