Genetic and metabolic disorders: hereditary angioedema: practice question

A Pediatrics 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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Pediatrics · Genetic and metabolic disorders: hereditary angioedema

Sample item

A 9-year-old has recurrent painless, non-itchy swelling of the face and limbs, and episodes of severe abdominal colic after minor trauma. There is no urticaria and no response to antihistamines or corticosteroids. His father had laryngeal swelling. Which screening test is most useful?

ASerum tryptase level taken within hours of an attackBSkin prick testing to common food allergensCSerum C4 level, which is low even between attacksDTotal serum IgE with a specific food IgE panel

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

The answer and the reasoning

C. Serum C4 level, which is low even between attacks

Hereditary angioedema is an autosomal dominant C1 esterase inhibitor deficiency causing bradykinin-mediated swelling without urticaria. Serum C4 is low even between attacks and is the screening test, followed by C1 inhibitor level and function.

Option by option

A. Serum tryptase level taken within hours of an attack
Tryptase rises in mast cell mediated reactions such as anaphylaxis, and this swelling is bradykinin mediated.
B. Skin prick testing to common food allergens
Skin prick testing assesses IgE-mediated food allergy, which is not the mechanism here.
C. Serum C4 level, which is low even between attacks (correct)
Correct. A low C4 screens for C1 inhibitor deficiency and persists between attacks.
D. Total serum IgE with a specific food IgE panel
Total and food-specific IgE assess atopic allergy, which does not explain non-itchy swelling without urticaria.

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.

Questions about this Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, Serum C4 level, which is low even between attacks. Hereditary angioedema is an autosomal dominant C1 esterase inhibitor deficiency causing bradykinin-mediated swelling without urticaria.

Why is "Serum tryptase level taken within hours of an attack" not the answer?

Tryptase rises in mast cell mediated reactions such as anaphylaxis, and this swelling is bradykinin mediated.

Why is "Skin prick testing to common food allergens" not the answer?

Skin prick testing assesses IgE-mediated food allergy, which is not the mechanism here.

Why is "Total serum IgE with a specific food IgE panel" not the answer?

Total and food-specific IgE assess atopic allergy, which does not explain non-itchy swelling without urticaria.

What concept does this question test?

It tests Genetic and metabolic disorders: hereditary angioedema in Pediatrics. Serum C4 is low even between attacks and is the screening test, followed by C1 inhibitor level and function.

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 Genetic and metabolic disorders: hereditary angioedema?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.