Angioedema is a swelling of the tissues that produce mucous, causing blockage and constriction of the airways. It is similar to anaphylactic shock, but has a different underlying cause. It is also similar to the reaction that causes hives, but in angioedema the effect is below the surface of the skin instead of within it. In most cases, angioedema is set off by an allergic reaction and can be treated identically to anaphylaxis – with adrenaline. However, in hereditary angioedema, an attack can be set off by numerous stimuli, such as trauma, stress or even dental work.
Unlike the allergic form, hereditary angioedema will not respond to adrenaline or the usual treatment for severe allergies – corticosteroids. Instead, acute attacks must be treated with intubation or tracheotomy unless a scarce blood factor known as C1-IHN is available. C1-INH must be used on hereditary angioedema patients who undergo surgery or dental work as most suffer an attack under anesthetic.
For long term relief, drugs must be taken to increase the production of C1-IHN in the body. Male hormones such as synthetic testosterone will have this effect and lessen the severity and frequency of attacks. However, such therapy must be avoided for children and pregnant women.
Angioedema is very difficult to diagnose. The symptoms are similar to other conditions, such as severe allergic reactions. However, the two conditions have to be treated differently and this is useful to establish a differential diagnosis.