C1 inhibitor deficiency causes hereditary angioedema (HAE). Patients present with acute deep tissue oedema, typically of the face, larynx or abdomen, which can be life threatening if respiratory obstruction occurs. 85 % of HAE patients have low antigenic C1 esterase inhibitor levels (type I HAE). The C4 level is low, especially during attacks. Request alongside C3 and C4 levels, plus C1 functional activity.
Recurrent angioedema, laryngeal oedema, or abdominal pain in the absence of urticaria Family history
RST (rust top) Separate and freeze immediately Transport frozen
5-10 mL (1 mL serum)