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HAE is a rare type of angioedema, occurring in only 2% of all patients with angioedema. The other types of angioedema, which are not inherited, can be broadly categorized as histamine-mediated and bradykinin-mediated, as explained below. Knowing the other types and causes of angioedema is important for accurate diagnosis and proper treatment.
- Histamine-mediated angioedema. Histamine is a chemical released by cells in the body during an
allergic reaction. The vast majority of patients with histamine-mediated angioedema have symptoms of hives (urticaria)
and itching (pruritus). Histamine, as with bradykinin in HAE, can cause vasodilation and increased blood-vessel
permeability. Different forms of histamine-mediated angioedema are explained below.
- Allergic angioedema. A common form of histamine-mediated angioedema is allergic angioedema,
which is triggered by exposure to an allergen or a physical factor. Some known allergens for histamine-mediated
angioedema include the following:
- foods such as peanuts, shellfish, and eggs
- drugs such as penicillin, sulfonamides, some antidepressants (SSRIs), buprionon, sitagliptin,
systemic antifungal agents, and some vaccines
- insect venoms
- latex
- Other forms of histamine-mediated angioedema. Other triggers of histamine-mediated
angioedema include aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), radiocontrast agents (barium or
iodine compounds sometimes used in X-rays), opiates, and vancomycin.
- Bradykinin-mediated angioedema. In bradykinin-mediated angioedema, excess bradykinin is generated,
resulting in vasodilation (widening of blood vessels) and blood-vessel permeability (or “leakiness”), which leads to
fluid buildup in body tissues (edema) and angioedema symptoms. Different forms of bradykinin-mediated angioedema are
explained below.
- HAE. See Disease process and Bradykinin: instigator of HAE attacks.
- Acquired angioedema. Acquired angioedema is rare and is caused by increased breakdown of
C1-INH. Acquired angioedema typically occurs in patients with lymphoproliferative disease and when there are autoantibodies to C1-INH.
- ACE-inhibitor–induced angioedema. ACE inhibitors, drugs widely used for hypertension and
chronic heart failure, increase the risk for bradykinin-mediated angioedema. The drugs may slow the breakdown
of bradykinin, leading to accumulation of bradykinin and resulting in vasodilation, capillary leakage, and edema.
Because so many people are currently using these agents, ACE-inhibitor–induced angioedema is recognized as a
common cause of nonallergic angioedema.
- Idiopathic angioedema. Idiopathic angioedema is classified as histamine-mediated when no specific causative agent can be identified. It is characterized by swelling and/or hives and is responsive to antihistamines. Idiopathic Angioedema also includes angioedema that presents without hives and is unresponsive to antihistamines. In these cases the angioedema may be mediated by some other as yet unknown or identified mechanism.
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