How is Hereditary Angioedema diagnosed?

Hereditary Angioedema (HAE) is a rare genetic disorder characterized by recurrent episodes of swelling in various parts of the body, including the skin, gastrointestinal tract, and airways. It is caused by a deficiency or dysfunction of a protein called C1 inhibitor (C1-INH), which plays a crucial role in regulating the immune system and preventing excessive inflammation.

Diagnosing HAE can be challenging due to its rarity and the similarity of symptoms to other conditions. However, there are several key steps and diagnostic tests that healthcare professionals use to identify and confirm the presence of HAE.

Medical History and Physical Examination

The initial step in diagnosing HAE involves taking a detailed medical history of the patient. The healthcare provider will ask about the frequency, duration, and characteristics of the swelling episodes, as well as any family history of similar symptoms. It is important to mention any triggers or factors that seem to provoke the episodes, such as stress, trauma, hormonal changes, or certain medications.

Following the medical history, a thorough physical examination will be conducted. The healthcare provider will assess the location, extent, and duration of the swelling episodes, as well as any associated symptoms. They will also examine the patient's family members for any signs of HAE.

Laboratory Tests

Several laboratory tests are used to confirm the diagnosis of HAE and differentiate it from other conditions with similar symptoms. These tests include:

• C1-INH Level: This blood test measures the level of C1-INH protein in the blood. HAE patients typically have low levels of functional C1-INH.


• C4 Level: Another blood test that measures the level of complement component C4, which is typically low in HAE patients.


• C1-INH Function: This test assesses the functional activity of C1-INH in the blood. HAE patients usually have reduced or dysfunctional C1-INH.


• C1q Level: C1q is a protein involved in the complement system. Its level is usually normal in HAE patients but decreased in other types of angioedema.


• Genetic Testing: In some cases, genetic testing may be performed to identify specific mutations or alterations in the genes responsible for HAE. This test can help confirm the diagnosis and determine the type of HAE.

Imaging Studies

In certain situations, imaging studies may be necessary to evaluate the extent and location of swelling episodes. These studies can help rule out other causes of swelling and identify any potential complications. Imaging techniques such as ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) may be used to visualize the affected areas.

Other Considerations

It is important to note that the diagnosis of HAE is often based on a combination of clinical findings, laboratory tests, and the exclusion of other possible causes. The healthcare provider will consider the patient's symptoms, medical history, family history, and test results to make an accurate diagnosis.

If HAE is suspected but the initial tests are inconclusive, the healthcare provider may refer the patient to a specialist, such as an allergist, immunologist, or hematologist, who has expertise in diagnosing and managing HAE.

In conclusion, diagnosing Hereditary Angioedema involves a comprehensive evaluation of the patient's medical history, physical examination, laboratory tests, and sometimes imaging studies. The combination of these diagnostic approaches helps healthcare professionals confirm the presence of HAE, differentiate it from other conditions, and determine the appropriate treatment plan for the patient.

by Diseasemaps