Hereditary angioedema. Undersuspected, underdiagnosed

Although hereditary angioedema accounts for only a small fraction of all angioedema, it is relatively common among inherited deficiencies of plasma proteins. The occurrences of upper respiratory obstruction, of attacks following trauma, and of episodes of abdominal pain are clues to the diagnosis, and the absence of a family history is no reassurance against it. Measurement of C4 concentration is a useful screening test: Normal values exclude the diagnosis, while subnormal values mandate measurement of C1 INH by immunoassay or functional assay. The functional assay is required to detect the genetic variant form. The importance of making the diagnosis is threefold. It facilitates prevention of life-threatening complications, such as upper airway obstruction and needless abdominal surgery. It leads to use of short-term prophylactic measures to prevent complications associated with trauma. In patients with disability due to frequent attacks, suppression or elimination of all symptoms can be achieved by chronic treatment with impeded androgens.