Vitamins and minerals: vitamin K malabsorption in biliary obstruction: 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 · Vitamins and minerals: vitamin K malabsorption in biliary obstruction

Sample item

A 55-year-old man with obstructive jaundice from a pancreatic head tumour has a prolonged prothrombin time. It corrects within 24 hours of an intramuscular vitamin K injection. What is the cause of the coagulopathy?

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

The answer and the reasoning

B. Malabsorption of fat-soluble vitamins from lack of bile salts in the gut

Bile salts are needed to form micelles for absorbing vitamins A, D, E and K. In biliary obstruction vitamin K is not absorbed, so factors II, VII, IX and X are not carboxylated. Correction after parenteral vitamin K shows that the liver can still synthesise the factors, which separates this from hepatocellular failure.

Option by option

  • A. Consumption of clotting factors by widespread small-vessel thrombi

    Consumption coagulopathy does not correct with vitamin K and shows low platelets and fibrinogen.

  • B. Malabsorption of fat-soluble vitamins from lack of bile salts in the gut (correct)

    Correct. Without bile salts vitamin K is malabsorbed, and parenteral vitamin K bypasses the gut.

  • C. Failure of damaged hepatocytes to synthesise any clotting factors at all

    Synthetic failure would not correct promptly with vitamin K.

  • D. Circulating autoantibodies directed against clotting factor VIII

    Factor VIII inhibitors prolong the aPTT and do not correct with vitamin K.

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 B, Malabsorption of fat-soluble vitamins from lack of bile salts in the gut. Bile salts are needed to form micelles for absorbing vitamins A, D, E and K.

Why is "Consumption of clotting factors by widespread small-vessel thrombi" not the answer?

Consumption coagulopathy does not correct with vitamin K and shows low platelets and fibrinogen.

Why is "Failure of damaged hepatocytes to synthesise any clotting factors at…" not the answer?

Synthetic failure would not correct promptly with vitamin K.

Why is "Circulating autoantibodies directed against clotting factor VIII" not the answer?

Factor VIII inhibitors prolong the aPTT and do not correct with vitamin K.

What concept does this question test?

It tests Vitamins and minerals: vitamin K malabsorption in biliary obstruction in Biochemistry. In biliary obstruction vitamin K is not absorbed, so factors II, VII, IX and X are not carboxylated. Correction after parenteral vitamin K shows that the liver can still synthesise the factors, which separates this from hepatocellular failure.

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 Vitamins and minerals: vitamin K malabsorption in biliary obstruction?

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.