Question 1

How is hereditary angioedema (HAE) diagnosed?

Accepted Answer

HAE is diagnosed by low C4 level (screening test) followed by low C1-esterase inhibitor level (type I) or activity (type II). C1q level is normal (distinguishing from acquired angioedema). Type III HAE (normal C1-INH) requires genetic testing for F12, PLG, or ANGPT1 mutations. Diagnosis should be confirmed in all patients with recurrent angioedema without urticaria.

Question 2

Why does ACE-inhibitor angioedema not respond to antihistamines?

Accepted Answer

ACE-inhibitor-induced angioedema is bradykinin-mediated, not histamine-mediated. ACE inhibitors block the degradation of bradykinin, leading to accumulation and increased vascular permeability. Antihistamines, corticosteroids, and epinephrine are largely ineffective. Treatment is supportive (airway management) with icatibant as a specific therapy for severe cases.

Question 3

What is the airway management approach for laryngeal angioedema?

Accepted Answer

Early assessment of airway patency is essential. Signs of impending compromise: stridor, dysphonia, inability to handle secretions, rapid progression. Awake fibreoptic intubation is preferred (difficult airway cart and ENT/surgical airway backup). Blind nasal intubation is contraindicated. Cricothyroidotomy may be required. Do not wait for imaging — examine and intervene if progressive.

Question 4

How long should a patient be observed after tongue angioedema?

Accepted Answer

Histaminergic angioedema: observe for 6–8 hours after symptom onset and ensure response to treatment before discharge. Bradykinin-mediated (HAE, ACE-I): symptoms progress over 24–36 hours and resolve over 2–5 days. Patients with tongue or oropharyngeal involvement should be observed for at least 24 hours due to risk of progression.