Knowledge of liver tests are essential for the daily practice of gastroenterology and endoscopy. The response of the liver to various types of injury varies and is often reflected by differentiated elevation of different liver tests. Classic examples are a ratio of 2:1 of AST:ALT in alcohol-induced liver injury, however, with AST rarely surpassing 50 IU/L, unless there is an additional insult, such as acetaminophen.