Visceral CLET iRAT 3 Practice Test

When the liver is involved, two stages of bilirubin handling can be disrupted: conjugation inside hepatocytes and excretion into bile. Bilirubin starts as indirect (unconjugated) bilirubin, which the liver normally conjugates to become direct (conjugated) bilirubin for drainage into the bile. If hepatocytes are damaged or their ability to conjugate bilirubin is impaired, indirect bilirubin rises. If bile flow or canalicular excretion is impaired—because of hepatocellular injury or cholestasis—direct bilirubin rises as well. Because liver disease can affect both conjugation and excretion, you often see elevations in both forms. If only one form were elevated, it would suggest a more specific problem, but liver involvement frequently produces a mixed hyperbilirubinemia with increases in both indirect and direct bilirubin.