An increase in which type of bilirubin indicates biliary obstruction?

An increase in direct (conjugated) bilirubin indicates biliary obstruction. When there is an obstruction in the bile duct system, the flow of bile becomes impaired. Bile is produced in the liver and contains conjugated bilirubin, which is water-soluble and normally excreted into the bile for elimination from the body via the intestines.

In cases of biliary obstruction, direct bilirubin accumulates in the bloodstream because it cannot be properly excreted into the bile. This leads to an elevation in serum levels of direct bilirubin, signaling the presence of an obstruction. Direct bilirubin is typically elevated in conditions involving cholestasis or biliary tract issues, while indirect (unconjugated) bilirubin is often associated with hemolysis or liver dysfunction, where the liver is unable to process bilirubin efficiently. Thus, monitoring bilirubin levels helps in diagnosing and managing conditions related to liver and biliary health.