Bile Acids

Bile acids are made by the liver from cholesterol, stored in the gallbladder, and recycled through the enterohepatic circulation between the gut and liver. Serum levels rise when the liver cannot efficiently clear bile acids from portal blood, which makes them a sensitive and specific indicator of structural liver disease and impaired bile flow (cholestasis). Levels can be elevated even when ALT, AST, and alkaline phosphatase are still normal, so this test adds resolution that a routine liver panel can miss. The best-known use is intrahepatic cholestasis of pregnancy, where intense third-trimester itching is accompanied by bile acids often three or more times above normal, and the result guides delivery timing because elevated bile acids carry fetal risk. Metabolic conditions such as Gilbert, Crigler-Najjar, and Dubin-Johnson syndromes typically do not raise bile acids, which helps separate them from true cholestatic disease.

This is the general serum total bile acid measurement for evaluating liver and bile flow function. The separate Bile Acids Panel, Pregnancy fractionates the individual acids and is the right choice when the specific question is intrahepatic cholestasis of pregnancy.