Immunology: hereditary angioedema: practice question

A Microbiology 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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Microbiology · Immunology: hereditary angioedema

Sample item

A young woman has recurrent episodes of non-pitting facial swelling and severe abdominal pain after minor dental work. There is no urticaria and antihistamines and adrenaline do not help. Which laboratory finding is most expected?

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

The answer and the reasoning

B. Low C4 level

C1 esterase inhibitor deficiency allows uncontrolled C1 activity and bradykinin generation, consuming C4. Low C4 is the screening test, and C1 inhibitor level or function confirms the diagnosis. Swelling does not respond to antihistamines because it is bradykinin mediated, not histamine mediated.

Option by option

  • A. Raised total IgE

    IgE is not the mediator in this condition.

  • B. Low C4 level (correct)

    Correct. Low C4 is the screening finding in C1 inhibitor deficiency.

  • C. Raised serum tryptase

    Raised tryptase marks mast cell degranulation, as in anaphylaxis.

  • D. Low C5 level

    C5 is a terminal component and is not consumed in this disorder.

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 Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is B, Low C4 level. C1 esterase inhibitor deficiency allows uncontrolled C1 activity and bradykinin generation, consuming C4.

Why is "Raised total IgE" not the answer?

IgE is not the mediator in this condition.

Why is "Raised serum tryptase" not the answer?

Raised tryptase marks mast cell degranulation, as in anaphylaxis.

Why is "Low C5 level" not the answer?

C5 is a terminal component and is not consumed in this disorder.

What concept does this question test?

It tests Immunology: hereditary angioedema in Microbiology. Low C4 is the screening test, and C1 inhibitor level or function confirms the diagnosis. Swelling does not respond to antihistamines because it is bradykinin mediated, not histamine mediated.

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 Immunology: hereditary angioedema?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.