The daily educational pearl – Angioedema without urticaria

Angioedema without urticaria

= non-mast cell mediated form of angioedema

– due to accumulation of bradykinin (ACE-inhibitors, ARBs – angiotensin receptor blockers) or to excessive activation of the complement pathway (usually due to C1 inhibitor deficiency)


– if patient is on ACEIs or ARBs, no routine tests are indicated

– if hereditary angioedema is suspected (secondary to C1 inhibitor deficiency), a C4 level should be requested

– a C4 level of 100% rules out C1 inhibitor deficiency

– a C4 level of less than 50% is diagnostic of C1 inhibitor deficiency


– airway management is most important

– stop ACEIs and ARBs and make sure to inform the patient and the patient’s GP / specialist so they are not started again

– adrenaline / antihistamines / steroids can be tried but there is no evidence that they are of any benefit


To find out about C1 inhibitor deficiency see tomorrow’s pearl.