The alanine aminotransferase (ALT) blood test is typically used to detect liver injury. GPT/ALT test is often ordered in conjunction with aspartate aminotransferase (AST) or as part of a liver panel to screen for and/or help diagnose liver disease. AST and ALT are considered to be two of the most important tests to detect liver injury, although ALT is more specific than AST. Sometimes AST is compared directly to ALT and an AST/ALT ratio is calculated. This ratio may be used to distinguish between different causes of liver damage. GPT values are often compared to the results of other tests such as alkaline phosphatase (ALP), total protein, and bilirubin to help determine which form of liver disease is present. ALT is often used to monitor th