What is the significance of GGT elevation in liver function tests?

• A. GGT elevation specifically indicates renal failure.
• B. GGT elevation suggests cholestasis or biliary tract involvement and can be induced by alcohol; helps differentiate hepatic from bone sources of ALP.
• C. GGT elevation rules out alcoholic liver disease.
• D. GGT elevation only occurs with bone disease.

Answer: (B)

GGT is a liver and biliary tract enzyme that rises when bile flow is impaired or when the hepatobiliary system is stressed, such as in cholestasis or biliary obstruction. This makes it a useful companion to alkaline phosphatase: if both are elevated, the source is likely hepatic/biliary; if alkaline phosphatase is elevated but GGT is not, bone is the more likely source. Alcohol can increase GGT as well, but this is not specific to alcoholic liver disease—many liver conditions and certain drugs can raise it. So, an elevated GGT points to hepatobiliary involvement and helps distinguish hepatic from bone origins of ALP.