What is the most specific indicator of cholestasis?

The most specific indicator of cholestasis is gamma-glutamyl transferase (GGT). GGT is an enzyme found primarily in the liver, and its levels increase in response to liver disease, particularly those conditions affecting bile flow. While alkaline phosphatase (ALP) levels can also elevate with cholestasis, they are not exclusive to liver problems and can rise due to bone disease or other factors.

Bilirubin, while useful in evaluating liver function and bile flow, does not specifically indicate cholestasis since its elevation can result from various forms of liver dysfunction or hemolysis. Aspartate aminotransferase (AST) is more associated with hepatocellular injury rather than cholestasis, making it less specific in this context. Therefore, GGT serves as the most precise marker for cholestasis, as it specifically correlates with bile duct function and liver-related biliary obstruction.