Clinical review of hereditary angioedema: diagnosis and management.

Hereditary angioedema (HAE) is caused by a deficiency in C1 esterase inhibitor and is characterized by sudden attacks of edema associated with discomfort and pain. The disease places patients at risk for disability and death if left untreated. Symptom severity and frequency can be extremely variable even among affected members of the same family. Attacks are not associated with inflammation or allergy, with most occurring secondary to trauma or stress. Swelling can affect any part of the body or multiple sites at once. Commonly affected areas include the extremities, genitalia, trunk, gastrointestinal tract, face, and larynx. Swelling typically worsens over 24 to 36 hours and resolves within 48 hours in less severe cases. Attacks result in 15,000 to 30,000 emergency department visits each year. Many of these emergency cases will undergo unnecessary surgeries or medical procedures due to misdiagnosis. The hallmarks of HAE--recurrent episodes of swelling without urticaria, a family history of HAE, first attack in childhood, and worsening at puberty--can be identified by a thorough family history, and the diagnosis can be confirmed by laboratory studies. Nevertheless, diagnosis may be delayed by 2 decades. We review available therapies and clinical characteristics that will both help clinicians diagnose HAE and distinguish among emergencies and nonemergency cases.