C1 Esterase Inhibitor (C1-INH) Tes

The C1 Esterase Inhibitor (C1-INH) test measures the level and functional activity of a key protein that regulates the complement system, a vital part of your immune response. This test is typically requested for people who experience unexplained, recurrent episodes of swelling (angioedema) affecting the face, limbs, abdomen, or airways, or for those with a family history of hereditary angioedema (HAE). It helps distinguish between hereditary and acquired forms of C1-INH deficiency and other causes of swelling.

A simple blood sample is taken by a trained phlebotomist. The sample is analysed using immunochemical and functional assays to assess both the quantity and the working capacity of C1-INH.

What is measured
- C1 Esterase Inhibitor (C1-INH) antigen: the amount of C1-INH protein present in the blood.
- C1 Esterase Inhibitor (C1-INH) function: the ability of the protein to inhibit its target enzymes, which is crucial for controlling complement activation.

Why it matters
C1-INH deficiency can lead to unpredictable and potentially life-threatening swelling attacks, particularly if the airway is involved. Early diagnosis guides appropriate management, including avoidance of triggers and access to targeted therapies, and helps prevent unnecessary treatments. Identifying the exact type of deficiency also informs genetic counselling and family screening.

• C1 Esterase Inhibitor (C1-INH) antigen
• C1 Esterase Inhibitor (C1-INH) function

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.