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ALL / Haematology

Hereditary angioedema

Hereditary angioedema

Hereditary angioedema (HAE) is an autosomal dominant condition associated with low plasma levels of the C1 inhibitor (C1-INH, C1 esterase inhibitor) 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
    • HAE does not respond to adrenaline, antihistamines, or glucocorticoids
    • IV C1-inhibitor concentrate, fresh frozen plasma (FFP) if this is not available
  • prophylaxis: anabolic steroid Danazol may help
+PassMedicine Notes

Hereditary angioedema (HAE) is an autosomal dominant condition associated with low plasma levels of the C1 inhibitor (C1-INH, C1 esterase inhibitor) 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
    • HAE does not respond to adrenaline, antihistamines, or glucocorticoids
    • IV C1-inhibitor concentrate, fresh frozen plasma (FFP) if this is not available
  • prophylaxis: anabolic steroid Danazol may help


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