Glossary of Terms

“Now that I know more about HAE, I still worry, but I would not change my experiences. My HAE has made me stronger and more determined.”

Liz — Diagnosed with HAE in 2013
Glossary of hereditary angioedema terms

Discover definitions

A rare disease like hereditary angioedema (HAE) can mean reading through a lot of complicated language and medical terminology.

The part of the body between the chest and pelvis that surrounds the stomach, intestines, liver, spleen and pancreas. This is a common location affected during an HAE attack. Before diagnosis, abdominal attacks can be confused with other medical conditions, such as appendicitis or irritable bowel syndrome.

On-demand, or acute, HAE treatment is medicine used to treat the symptoms of an HAE attack.

Antihistamines are medications used to relieve allergy symptoms, like sneezing and itching. Antihistamines do not help reduce the swelling in an HAE attack.

Appendicitis is a serious medical condition in which the appendix becomes inflamed and painful. Appendicitis requires prompt surgery. Left untreated, an inflamed appendix will eventually burst, or perforate, and spread infection into other parts of the body.

Bradykinin is a protein found in the blood. When there is too much bradykinin in the blood, it can cause blood vessels to leak into surrounding tissue, causing the swelling, inflammation and pain experienced during an HAE attack.

C1-esterase is a protein found in the blood. When it's at normal levels and working properly, it helps to regulate inflammation in the body. If there's not enough working C1-esterase inhibitor, your body isn't able to perform this function — and that can put you at risk of an HAE attack.

A protein found in blood that plays an important role in the immune system. It helps kill disease-causing bacteria and viruses. Measuring C4 levels can help your doctor diagnose and monitor treatment of certain diseases, such as HAE.

Epinephrine is a hormone used to treat severe allergic reactions. It is available as a drug to treat many conditions but does not help reduce the swelling in an HAE attack.

Estrogens are female sex hormones. They’re important for sexual and reproductive development. Estrogens can also be included in oral contraceptives, hormone replacement therapy and other medications. Studies have shown that fluctuations in estrogen may influence HAE attacks.

Glucocorticoids are steroid hormones that regulate many functions of the body, including inhibiting inflammatory, allergic and immune responses. Glucocorticoids do not help reduce the swelling of an HAE attack.

Hereditary angioedema (HAE) is a rare genetic disorder. Most cases of HAE are caused by a deficiency in a protein called C1-esterase inhibitor, or the protein they have doesn’t work the way it should.

Irritable bowel syndrome (IBS) is a problem that affects the large intestine. It can cause abdominal cramping, bloating and a change in bowel habits. HAE is often mistaken for IBS. This is because IBS is a far more common condition and the symptoms can resemble those of an HAE attack in the abdomen.

Kallikrein is a chemical found in the body that breaks apart certain proteins in order to form others, such as bradykinin, the protein that causes swelling during an HAE attack.

The larynx, which is what swells during a laryngeal HAE attack, is more commonly known as the voice box. Because of the potential risk of suffocation, an HAE attack affecting this area requires emergency care as soon as possible.

Prophylactic HAE treatment involves taking medicine routinely to help prevent HAE attacks or reduce the frequency and severity of HAE attacks.

Beneath the skin. This is one of the primary locations for HAE attacks. Subcutaneous attacks are often mistaken for allergic reactions.

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