Which liver enzyme is classically used to assess hepatocellular injury?

• A. Aspartate aminotransferase (AST)
• B. Gamma-glutamyl transferase (GGT)
• C. Alanine aminotransferase (ALT)
• D. Alkaline phosphatase (ALP)

Answer: (C)

When hepatocytes are damaged, their enzymes leak into the blood. Alanine aminotransferase is highly concentrated in liver cells and is more liver-specific than other transaminases, so its elevation most clearly reflects hepatocellular injury. While AST can also rise, it is less specific because it’s found in heart and muscle as well. Enzymes like gamma-glutamyl transferase and alkaline phosphatase tend to rise with cholestasis or biliary injury rather than direct hepatocyte damage. So ALT stands out as the classic marker for hepatocellular injury.