C1 esterase inhibitor / activity

General Information

C1 esterase inhibitor (C1-INH) is a highly glycosylated polymorphic protein that belongs to a family of serine protease inhibitors called serpins.

C1 esterase inhibitor (C1-INH) is a major blocker of activated factor XII. It also inactivates plasmin, factor XI, kallikrein. It is also the only inhibitor of complement components C1 and C2.

In addition, C1 esterase inhibitor (C1-INH) is an acute inflammatory reactant and its production is stimulated by interleukin 6, α-interferon and γ-interferon.

Deficiency of C1 esterase inhibitor (C1-INH) leads to changes that eventually lead to increased permeability of blood vessel walls and the development of angioedema or vascular swelling. The deficiency may be congenital or acquired.

Congenital angioedema is an autosomal dominant disease. It is characterized by a decrease in the synthesis of C1 esterase inhibitor (C1-INH), or by the synthesis of an anomalous variant. The disease proceeds with periodic, recurring painless swellings of the subcutaneous and submucous tissue. The tissues of the face, limbs, genitals, respiratory and digestive system are most often affected. During the intestinal form, the exacerbation episode occurs with intestinal colic, vomiting, diarrhea. The development of an episode of edema in the trachea may end with obstruction and a lethal outcome.

Episodes of the disease are self-limiting in 2-5 days. The periodicity, frequency, duration and severity of edema episodes are heterogeneous. The release mechanism has not been fully studied.

Acquired forms of angioedema associated with C1 esterase inhibitor (C1-INH) deficiency are predominantly found in elderly people with lymphoproliferative, autoimmune (systemic lupus erythematosus and eosinophilia), neoplastic diseases (with the development of anti-C1-INH antibodies).

Other forms of acquired angioedema are: allergic, pseudoallergic, and idiopathic angioedema.

When is the survey conducted?

Determination of C1 esterase inhibitor (C1-INH) deficiency is recommended for diagnostics and monitoring of congenital angioedema.

Preparation of the patient:  It does not require prior preparation.

Material for examination: Venous blood

Reference limits: 70-130% 

Interpretation of results:

Getting a low rate (<10-35%) indicates the presence of a genetic form of angioedema.