GI physiology: bilirubin metabolism: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

Try it

Physiology · GI physiology: bilirubin metabolism

Sample item

A 55-year-old man has painless jaundice, dark urine, pale stools and itching. A carcinoma of the head of the pancreas obstructs the common bile duct. Which urinary finding is expected?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Bilirubin present and urobilinogen absent

Conjugated bilirubin is water soluble and appears in urine when it regurgitates into plasma, giving dark urine. Urobilinogen is formed by bacterial action on bilirubin in the intestine, so when bile cannot reach the gut it is absent from stool and urine, and the stools are pale. In haemolysis, in contrast, unconjugated bilirubin is not found in urine but urobilinogen increases.

Option by option

  • A. Bilirubin absent and urobilinogen increased

    This pattern, with raised urobilinogen and no bilirubin, belongs to haemolytic jaundice.

  • B. Bilirubin and urobilinogen both increased

    Both raised would be expected in hepatocellular disease with partial obstruction, not complete obstruction.

  • C. Bilirubin absent and urobilinogen absent

    Conjugated bilirubin is present in urine in obstruction, so bilirubin is not absent.

  • D. Bilirubin present and urobilinogen absent (correct)

    Obstruction gives bilirubinuria with absent urobilinogen.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Physiology questions

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, Bilirubin present and urobilinogen absent. Conjugated bilirubin is water soluble and appears in urine when it regurgitates into plasma, giving dark urine.

Why is "Bilirubin absent and urobilinogen increased" not the answer?

This pattern, with raised urobilinogen and no bilirubin, belongs to haemolytic jaundice.

Why is "Bilirubin and urobilinogen both increased" not the answer?

Both raised would be expected in hepatocellular disease with partial obstruction, not complete obstruction.

Why is "Bilirubin absent and urobilinogen absent" not the answer?

Conjugated bilirubin is present in urine in obstruction, so bilirubin is not absent.

What concept does this question test?

It tests GI physiology: bilirubin metabolism in Physiology. Urobilinogen is formed by bacterial action on bilirubin in the intestine, so when bile cannot reach the gut it is absent from stool and urine, and the stools are pale. In haemolysis, in contrast, unconjugated bilirubin is not found in urine but urobilinogen increases.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study GI physiology: bilirubin metabolism?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.