Which laboratory value is primarily used to assess liver function?

The primary laboratory value used to assess liver function is alanine aminotransferase (ALT). ALT is an enzyme predominantly found in the liver, and when liver cells are damaged, as seen in conditions such as hepatitis, cirrhosis, or fatty liver disease, the enzyme is released into the bloodstream. Elevated levels of ALT are indicative of liver injury, making it a key marker for evaluating liver health and function.

Bilirubin levels can also give insight into liver function, particularly regarding the liver's ability to process waste products, but it is not as specific in identifying liver cell injury compared to ALT. Creatinine primarily assesses kidney function, while hemoglobin is a marker for blood oxygen-carrying capacity and has no direct correlation to liver function. Therefore, ALT is the most relevant biomarker among the options provided to evaluate liver health.