Specimen Information

Type

Gold, SST

Volume

2.0 ml

Transport Info

Centrifuge and immediately transfer serum to separate plastic tube
Frozen

CRITICAL FROZEN – Separate samples must be submitted when multiple tests are ordered

Fasting Required?

False

Clinical Significance

C1-inhibitor (C1-INH) is a multispecific, protease inhibitor that is present in normal human plasma and serum, regulating enzymes of the complement, coagulation, fibrinolytic, and kininforming systems. The enzymes regulated by this protein include the C1r and C1s subunits of the activated first component of complement, activated Hageman Factor (factor XIIa), Hageman factor fragments, activated plasma thromboplastin antecedent (PTA or factor XIa), kallikrein (Fletcher factor), and plasmin. A deficiency of functionally active component of C1-INH may lead to life-threatening angioedema. Two major forms of C1-INH deficiency have been reported: the congenital form, termed hereditary angioedema (HAE), and the acquired form, which is associated with a variety of diseases, including lymphoid malignancies. Hereditary angioedema is characterized by transient but recurrent attacks of nonpruritic swelling of various tissues throughout the body. The gastrointestinal tract is often involved, as well, leading to recurrent episodes of cramping abdominal pain. The most frequent cause of death in this disease is airway obstruction secondary to laryngeal edema occurring during an attack. In the congenital form of angioedema, there is a quantitative deficiency in C-1- esterase inhibitor detectable by nephelometry. Acquired forms are usually associated with qualitative (functional) deficiency of the inhibitor. This is best detected by the enzyme immunoassay for the functional component.