In prehepatic jaundice due to acute hemolytic anemia, which bilirubin fraction is elevated?

In prehepatic jaundice due to acute hemolytic anemia, which bilirubin fraction is elevated?

• A. Conjugated bilirubin
• B. Unconjugated bilirubin
• C. Delta bilirubin
• D. Bilirubin in urine

Answer: (B)

The situation is prehepatic jaundice caused by rapid red blood cell breakdown, so there’s an overproduction of bilirubin. The liver can’t keep up with conjugating all of it, so the fraction that rises in the blood is the unconjugated bilirubin. It’s the unconjugated form that is not water-soluble and is carried in the bloodstream bound to albumin to be taken up by the liver for conjugation. Because production outpaces conjugation, unconjugated bilirubin accumulates in serum. Conjugated bilirubin would not be the main elevated fraction here; it’s the form that’s already been processed by the liver and is soluble, appearing more with liver dysfunction or biliary obstruction. Delta bilirubin tends to rise with chronic jaundice or after jaundice resolves, since it’s a conjugated bilirubin bound to albumin and has a long half-life. Bilirubin in urine is not elevated in this scenario because unconjugated bilirubin is not water-soluble and isn’t excreted in urine; only conjugated bilirubin appears in urine when present in the blood.

The situation is prehepatic jaundice caused by rapid red blood cell breakdown, so there’s an overproduction of bilirubin. The liver can’t keep up with conjugating all of it, so the fraction that rises in the blood is the unconjugated bilirubin. It’s the unconjugated form that is not water-soluble and is carried in the bloodstream bound to albumin to be taken up by the liver for conjugation. Because production outpaces conjugation, unconjugated bilirubin accumulates in serum.

Conjugated bilirubin would not be the main elevated fraction here; it’s the form that’s already been processed by the liver and is soluble, appearing more with liver dysfunction or biliary obstruction. Delta bilirubin tends to rise with chronic jaundice or after jaundice resolves, since it’s a conjugated bilirubin bound to albumin and has a long half-life. Bilirubin in urine is not elevated in this scenario because unconjugated bilirubin is not water-soluble and isn’t excreted in urine; only conjugated bilirubin appears in urine when present in the blood.