Hereditary Angioedema DIAGNOSIS
Identifying when to test and connecting signs and symptoms is key to a timely differential diagnosis of hereditary angioedema (HAE).1 Because delays in diagnosis can be life-threatening, it's critical to improve the time to an accurate diagnosis of HAE.1,2
Prioritize testing for hereditary angioedema (HAE) if your patient presents with a history of recurrent angioedema attacks and/or has a family history of diagnosed HAE.1,3
Additional presentations suggestive of HAE that should prompt testing include3:
- Onset of swelling in childhood or adolescence
- Recurrent and painful abdominal symptoms from gastrointestinal angioedema
- Angioedema attacks failing to respond to antihistamines, glucocorticoids, or epinephrine
- Exacerbation of angioedema symptoms with exogenous estrogens or ACE inhibitors
- Respiratory symptoms, including laryngeal edema
- Presence of prodromal signs or symptoms, including a tingling sensation or nonpruritic rash (erythema marginatum)
Connecting disparate swelling attacks and abdominal symptoms may help to identify HAE and prompt testing.1
Family screening
Due to the hereditary nature of HAE, family screening is also an important part of the diagnostic process.1
Family screening for HAE is recommended and encouraged for all blood relatives, including children, parents, siblings, grandparents, aunts, and uncles.1,3
Testing for HAE
To help confirm a differential HAE diagnosis, perform an HAE blood test: measure your patient's serum levels of C4 and antigenic and functional C1-INH levels.3,4
Laboratory findings for HAE Types I and II1,3
Angioedema type
Type I HAE
Type II HAE
C4 level
Low
Low
Angioedema type
Type I HAE
Type II HAE
C1-INH level
Low
Normal-Elevated
Angioedema type
Type I HAE
Type II HAE
Functional C1-INH level
Low
Low
Additionally, testing the level of C1q antigen can aid in the diagnosis and help to distinguish between HAE and acquired angioedema.1,3
Identifying HAE1,3
Start by testing
C1-INH function
C1-INH level
C4 level
C1q level
-
Low C1-INH function
Low C1-INH level
Low C4 level
Normal C1q levelConsider HAE Type 1
-
Low C1-INH function
Normal/high C1-INH level
Low C4 level
Normal C1q levelConsider HAE Type 2
-
Normal C1-INH function
Normal C1-INH level
Normal C4 level
Normal C1q levelIf symptoms persist, repeat blood tests during an attack. If blood tests are normal, consider a form of HAE caused by different mutations than Type I or Type II
Normal C1-INH-HAE
-
Low C1-INH function
Normal/low C1-INH level
Low C4 level
Low C1q levelConsider acquired angioedema
An accurate and early differential diagnosis is a vital first step in helping your patients with hereditary angioedema.1,2
