Clinical biochemistry: conjugated bilirubin bound to albumin: practice question

A Biochemistry 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.

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Biochemistry · Clinical biochemistry: conjugated bilirubin bound to albumin

Sample item

A patient's bile duct obstruction is relieved and conjugated bilirubin falls, but total bilirubin takes weeks to normalise. Which fraction, covalently bound to albumin, persists in plasma for the albumin half-life?

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

The answer and the reasoning

C. Delta bilirubin

In prolonged cholestasis some conjugated bilirubin binds covalently to albumin to form delta bilirubin, which clears only as the albumin is degraded, with a half-life of about 3 weeks. It explains why jaundice resolves slowly after the obstruction is relieved. It is measured as part of direct bilirubin by diazo methods.

Option by option

  • A. Unconjugated bilirubin

    Unconjugated bilirubin is bound non-covalently and is cleared by the liver.

  • B. Biliverdin

    Biliverdin is the green precursor reduced to bilirubin.

  • C. Delta bilirubin (correct)

    Correct. Albumin-bound delta bilirubin clears with the half-life of albumin.

  • D. Urobilinogen

    Urobilinogen is a colourless bowel-derived product, not an albumin adduct.

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.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Delta bilirubin. In prolonged cholestasis some conjugated bilirubin binds covalently to albumin to form delta bilirubin, which clears only as the albumin is degraded, with a half-life of about 3 weeks.

Why is "Unconjugated bilirubin" not the answer?

Unconjugated bilirubin is bound non-covalently and is cleared by the liver.

Why is "Biliverdin" not the answer?

Biliverdin is the green precursor reduced to bilirubin.

Why is "Urobilinogen" not the answer?

Urobilinogen is a colourless bowel-derived product, not an albumin adduct.

What concept does this question test?

It tests Clinical biochemistry: conjugated bilirubin bound to albumin in Biochemistry. It explains why jaundice resolves slowly after the obstruction is relieved. It is measured as part of direct bilirubin by diazo methods.

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 Clinical biochemistry: conjugated bilirubin bound to albumin?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.