Diagnosis & investigations


Pointers to a diagnosis of hereditary angioedema (HAE) are:

  • Family history – other family members have had similar symptoms
  • Recurrent episodes of swelling (without hives) lasting more than 24 hours and unresponsive to antihistamines
  • Recurrent unexplained abdominal pain
  • Symptoms starting in childhood and worsening in adolescence.



For diagnosis of HAE types I and II:

  • Serum C4 levels – usually low in untreated HAE.
  • If C4 is low, measure C1 INH level and function.
  • If C4 is normal but HAE is suspected, measure C1 INH levels and function, and if normal, repeat C4 levels during an attack and assess C1 INH level and function if abnormal.
  • Genetic testing may be done in some cases where there is doubt.


  • C4 and C1 INH levels are normal.
  • Diagnosis is from the clinical picture.
  • Kininogenase activity measurement and genetic analysis for F12 gene mutation may be considered.


Testing relatives

If you receive a positive diagnosis for HAE, it is advisable for relatives to be tested, whether or not they exhibit symptoms at the present time.

It is important that HAE patients are treated by a specialist who has experience of treating HAE patients.


HAE treatment centres

HAE patients may be treated by Immunologists, Allergy Specialists and Dermatologists in specialised HAE centres. Your nearest Immunology centre can be found by following this link.

Please contact HAE UK for information about your nearest HAE specialist centre.