Which enzyme is commonly used as a marker of cholestasis and included in hepatic panel?

• A. AST
• B. GGT
• C. ALP
• D. ALT

Answer: (B)

Cholestasis, or impaired bile flow, elevates enzymes linked to the biliary system. Among enzymes in a hepatic panel, gamma-glutamyl transferase (GGT) is particularly sensitive to biliary obstruction and cholestasis, so its rise supports a hepatobiliary issue. Unlike alkaline phosphatase, which is also produced in bone, GGT is not derived from bone, helping confirm that an ALP elevation originates in the liver rather than bone. Transaminases like AST and ALT reflect hepatocellular injury rather than cholestasis, and while ALP can rise with cholestasis, its lack of specificity makes GGT a better indicator in this context. Therefore, GGT is the enzyme commonly used as a marker of cholestasis and included in hepatic panels.