In biliary obstruction, which liver enzyme is typically elevated?

In biliary obstruction, which liver enzyme is typically elevated?

• A. Aspartate aminotransferase
• B. Alanine aminotransferase
• C. Lactate dehydrogenase
• D. Alkaline phosphatase

Answer: (D)

Biliary obstruction causes a cholestatic pattern of liver enzyme elevation, with alkaline phosphatase being the most characteristic. Alkaline phosphatase is produced by the cells lining the bile ducts, and when a blockage occurs, bile flow is impaired and these cells release more ALP into the bloodstream. This leads to a prominent rise in ALP relative to other enzymes. In contrast, AST and ALT reflect hepatocellular injury and are usually only modestly elevated unless there is accompanying liver cell damage. Lactate dehydrogenase is nonspecific and less helpful for identifying biliary obstruction. Thus, alkaline phosphatase best indicates biliary obstruction.

Biliary obstruction causes a cholestatic pattern of liver enzyme elevation, with alkaline phosphatase being the most characteristic. Alkaline phosphatase is produced by the cells lining the bile ducts, and when a blockage occurs, bile flow is impaired and these cells release more ALP into the bloodstream. This leads to a prominent rise in ALP relative to other enzymes. In contrast, AST and ALT reflect hepatocellular injury and are usually only modestly elevated unless there is accompanying liver cell damage. Lactate dehydrogenase is nonspecific and less helpful for identifying biliary obstruction. Thus, alkaline phosphatase best indicates biliary obstruction.