Which enzyme indicates biliary obstruction when elevated?

Gamma-glutamyl transpeptidase (GGT) is a specific enzyme that is particularly useful in indicating biliary obstruction when its levels are elevated. GGT is involved in the metabolism of glutathione and in the transfer of amino acids across the cellular membrane, and it is found in various tissues, with a higher concentration in the liver and biliary tract.

Elevated GGT is often associated with liver disease, bile duct obstruction, and conditions affecting the hepatobiliary system. When there is an obstruction in the bile ducts, GGT levels rise significantly, making it a reliable marker for biliary obstruction.

While other enzymes like alkaline phosphatase (ALP) also rise in cases of biliary obstruction, GGT can help differentiate between liver-related causes and other conditions, such as bone diseases. Thus, elevation of GGT specifically indicates issues that relate to the biliary system more directly than other enzymes.