Question:hard
(a) A patient presents with unconjugated hyperbilirubinemia and presence of urobilinogen in urine. Which amongst the following is the least likely diagnosis? (b) A related patient presents with unconjugated hyperbilirubinemia and elevated urobilinogen levels in urine, and the most likely diagnosis is asked. Choose the option that answers part (a), the least likely diagnosis.
(a) A patient presents with unconjugated hyperbilirubinemia and presence of urobilinogen in urine. Which amongst the following is the least likely diagnosis? (b) A related patient presents with unconjugated hyperbilirubinemia and elevated urobilinogen levels in urine, and the most likely diagnosis is asked. Choose the option that answers part (a), the least likely diagnosis.
Show Hint
In a list of unconjugated jaundice causes, the conjugated-defect outlier is the odd one out.
Updated On: Jun 24, 2026
- Hemolytic jaundice
- Crigler Najjar syndrome
- Gilbert's syndrome
- Dubin Johnson syndrome
Show Solution
The Correct Option is D
Solution and Explanation
Two ideas unlock this question. First, unconjugated bilirubin is water-insoluble and bound to albumin, so it cannot pass into urine. Second, urinary urobilinogen reflects how much conjugated bilirubin reaches the gut, gets turned into urobilinogen, and is reabsorbed, so a high level means the conjugation-and-excretion pathway is busy.
The case describes unconjugated hyperbilirubinemia with urobilinogen in the urine. Hemolytic jaundice fits beautifully because excess red cell breakdown floods the liver, which conjugates and dumps a large load into the gut, raising urobilinogen sharply. Gilbert and Crigler Najjar are inherited shortfalls of the conjugating enzyme, so they too sit in the unconjugated camp.
Dubin Johnson syndrome is the misfit. Its problem lies after conjugation, at the canalicular pump (MRP2) that ships conjugated bilirubin into bile. The block raises the $conjugated$, direct fraction, producing conjugated hyperbilirubinemia, which is the opposite of what the stem states. So in a list of unconjugated causes, it is the least likely diagnosis.
For completeness, the partnered part of the item, asking the most likely cause of unconjugated jaundice with high urinary urobilinogen, points to hemolytic jaundice, because hemolysis drives the greatest urobilinogen output. But the requested answer, the least likely diagnosis, is the conjugated outlier.
\[\boxed{\text{Dubin Johnson syndrome}}\]
The case describes unconjugated hyperbilirubinemia with urobilinogen in the urine. Hemolytic jaundice fits beautifully because excess red cell breakdown floods the liver, which conjugates and dumps a large load into the gut, raising urobilinogen sharply. Gilbert and Crigler Najjar are inherited shortfalls of the conjugating enzyme, so they too sit in the unconjugated camp.
Dubin Johnson syndrome is the misfit. Its problem lies after conjugation, at the canalicular pump (MRP2) that ships conjugated bilirubin into bile. The block raises the $conjugated$, direct fraction, producing conjugated hyperbilirubinemia, which is the opposite of what the stem states. So in a list of unconjugated causes, it is the least likely diagnosis.
For completeness, the partnered part of the item, asking the most likely cause of unconjugated jaundice with high urinary urobilinogen, points to hemolytic jaundice, because hemolysis drives the greatest urobilinogen output. But the requested answer, the least likely diagnosis, is the conjugated outlier.
\[\boxed{\text{Dubin Johnson syndrome}}\]
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