Which enzyme is a transferase used as a marker for liver disease?

• A. Ornithine Carbamoyl Transferase
• B. ALT
• C. AST
• D. LAP

Answer: (A)

Alanine aminotransferase (ALT) is a transferase whose level in blood most specifically reflects hepatocellular injury. It transfers an amino group from alanine to alpha-ketoglutarate, producing pyruvate and glutamate. ALT is highly concentrated in liver cells, so when liver cell membranes are damaged, ALT leaks into the bloodstream, making it a sensitive and relatively liver-specific marker of liver disease.

In contrast, ornithine carbamoyl transferase is a mitochondrial enzyme of the urea cycle and isn’t used routinely as a clinical liver disease marker. Leucine aminopeptidase is not a primary marker for liver injury. Aspartate aminotransferase (AST) can be elevated in other tissues like heart and muscle, so it’s less specific than ALT for liver injury. Therefore, ALT is the best choice as a liver disease marker.