Understanding Lab Tests for Hereditary Angioedema
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Hereditary Angioedema (HAE) is a rare genetic disorder that causes episodes of severe swelling in various parts of the body, including the face, throat, hands, feet, and abdomen. This potentially life-threatening condition requires specific blood tests to confirm the diagnosis and monitor the complement system dysfunction.
Top Recommended Test
Complement Component C4c
C4c testing is crucial for HAE diagnosis, as patients with this condition characteristically have low C4c levels. The complement system overactivity leads to depletion of C4c, making this test a key diagnostic marker.
2907 reviews
How Blood Tests Diagnose Hereditary Angioedema
HAE is caused by deficiencies in the complement system, particularly involving C1 inhibitor protein. This leads to overactivity of the complement cascade, resulting in depletion of specific complement components. Blood tests measuring complement levels are essential for diagnosing this condition, as they can detect the characteristic low levels of C3c and C4c that occur in HAE patients.
Other Relevant Tests
Complement Component C3c
This test measures C3c levels in the blood. Hereditary Angioedema patients often show lower than normal C3c levels due to the overactive complement system that depletes complement components during swelling episodes.
2907 reviews
Complement Component C3c and C4c
This combined test measures both C3c and C4c levels simultaneously, providing a comprehensive assessment of complement system function. Low levels of both components can be indicative of Hereditary Angioedema.
2907 reviews
Complement Component C4, Pleural Fluid
This specialized test measures C4 levels in pleural fluid, which can be useful when HAE affects the respiratory system. Low complement C4 levels in pleural fluid can help confirm the diagnosis in cases where swelling affects the chest cavity.
2907 reviews
Understanding Your Results
Low levels of complement components, particularly C4c, are characteristic findings in Hereditary Angioedema. These tests help healthcare providers confirm the diagnosis and distinguish HAE from other causes of swelling. Regular monitoring of complement levels may also be necessary to assess disease activity and treatment response.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment. Given the potentially life-threatening nature of HAE, prompt medical evaluation is essential if you experience severe or recurring episodes of swelling.
