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Hereditary Angioedema — RACP Adult Medicine MCQ

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ModerateInfectious DiseasesHereditary AngioedemaRACP Adult Medicine

A 25-year-old woman presents with recurrent episodes of non-pruritic subcutaneous and mucosal swelling (angioedema) without urticaria. She has had episodes of abdominal pain from bowel wall oedema. Her mother has similar episodes. C4 is very low (0.02 g/L). C1 esterase inhibitor level is low and functional activity is reduced. C3 is normal. What is the most likely immunodeficiency?

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Correct answer: D — C1 esterase inhibitor deficiency

Recurrent angioedema without urticaria, abdominal pain from bowel oedema, family history (autosomal dominant), low C4 (screening test), and low C1 esterase inhibitor (level and function) is hereditary angioedema (HAE) type I. Low C4 is the best screening test (always low in HAE). Treatment of acute attacks: C1-INH concentrate (Berinert), icatibant (bradykinin B2 receptor antagonist), or fresh frozen plasma. Prophylaxis: lanadelumab (anti-kallikrein), berotralstat, or danazol.

Reference: ASCIA – 2024 – HAE Guidelines; WAO/EAACI 2024 HAE