In the early stage of hepatic dysfunction due to viral hepatitis, which bilirubin fraction is elevated?

In the early stage of hepatic dysfunction due to viral hepatitis, which bilirubin fraction is elevated?

• A. Elevation in urobilinogen and urobilin excretion in the feces
• B. Elevation in the serum unconjugated bilirubin fraction
• C. Depression in the serum conjugated bilirubin fraction
• D. Depression in urinary urobilinogen excretion

Answer: (B)

Early hepatitis-related liver injury primarily disrupts hepatocyte uptake and conjugation of bilirubin. When this conjugation step is impaired, unconjugated (indirect) bilirubin cannot be efficiently made water-soluble, so it accumulates in the blood and its serum fraction rises. The direct (conjugated) bilirubin isn’t the main elevated signal at this stage, because the initial problem is with conjugation itself rather than a failure to excrete conjugated bilirubin. Changes in urobilinogen excretion reflect bile flow and gut processing rather than the primary hepatic issue in this early phase, so they’re not the defining feature. Thus, the rising fraction is unconjugated bilirubin.

Early hepatitis-related liver injury primarily disrupts hepatocyte uptake and conjugation of bilirubin. When this conjugation step is impaired, unconjugated (indirect) bilirubin cannot be efficiently made water-soluble, so it accumulates in the blood and its serum fraction rises. The direct (conjugated) bilirubin isn’t the main elevated signal at this stage, because the initial problem is with conjugation itself rather than a failure to excrete conjugated bilirubin. Changes in urobilinogen excretion reflect bile flow and gut processing rather than the primary hepatic issue in this early phase, so they’re not the defining feature. Thus, the rising fraction is unconjugated bilirubin.