Blood and immunity: polycythaemia vera: 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.

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Physiology · Blood and immunity: polycythaemia vera

Sample item

A 58-year-old has facial plethora, itching after a hot bath, splenomegaly and a high haemoglobin. Which pattern of erythropoietin level and arterial oxygen saturation favours this diagnosis over secondary polycythaemia due to chronic hypoxia?

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

The answer and the reasoning

D. Low erythropoietin with normal oxygen saturation

Polycythaemia vera is a clonal marrow disorder, usually with a JAK2 mutation, in which red cell production is independent of erythropoietin, so levels are suppressed and oxygen saturation is normal. Secondary polycythaemia from hypoxia has high erythropoietin and, in chronic lung disease, low saturation.

Option by option

  • A. High erythropoietin with normal oxygen saturation

    High erythropoietin with normal saturation suggests an erythropoietin-secreting tumour.

  • B. High erythropoietin with low oxygen saturation

    High erythropoietin with low saturation suggests appropriate secondary polycythaemia from hypoxia.

  • C. Low erythropoietin with low oxygen saturation

    Low erythropoietin with low saturation is not the typical pattern of either condition.

  • D. Low erythropoietin with normal oxygen saturation (correct)

    Correct. In polycythaemia vera erythropoietin is suppressed and saturation is normal.

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 Physiology question

What is the answer to this Physiology question?

The best answer is D, Low erythropoietin with normal oxygen saturation. Polycythaemia vera is a clonal marrow disorder, usually with a JAK2 mutation, in which red cell production is independent of erythropoietin, so levels are suppressed and oxygen saturation is normal.

Why is "High erythropoietin with normal oxygen saturation" not the answer?

High erythropoietin with normal saturation suggests an erythropoietin-secreting tumour.

Why is "High erythropoietin with low oxygen saturation" not the answer?

High erythropoietin with low saturation suggests appropriate secondary polycythaemia from hypoxia.

Why is "Low erythropoietin with low oxygen saturation" not the answer?

Low erythropoietin with low saturation is not the typical pattern of either condition.

What concept does this question test?

It tests Blood and immunity: polycythaemia vera in Physiology. Secondary polycythaemia from hypoxia has high erythropoietin and, in chronic lung disease, low saturation.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Blood and immunity: polycythaemia vera?

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.