What chemical mediator is mainly responsible for the tissue oedema seen in patients in hereditary angioedema?
ExplanationD. HEREDITARY ANGIOEDEMA
Hereditary angioedema is an autosomal dominant condition associated with low plasma levels of the C1 inhibitor (C1-INH)
protein. C1-INH is a multifunctional serine protease inhibitor -the probable mechanism behind attacks is uncontrolled release of bradykinin resulting in oedema of tissues.
Investigation
• C1-INH level is low during an attack
• low C2 and C4 levels are seen, even between attacks.
Serum C4 is the most reliable and widely used screening tool
Symptoms
• attacks may be proceeded by painful macular rash
• painless, non-pruritic swelling of
subcutaneous/submucosal tissues
• may affect upper airways, skin or abdominal organs (can occasionally present as abdominal pain due to visceral oedema)
• urticaria is not usually a feature
Management
• acute: IV C1-inhibitor concentrate, fresh frozen plasma (FFP) if this is not available
• prophylaxis: anabolic steroid Danazol may help
