Complement C1 esterase inhibitor – functional
Functional C1 inhibitor levels must be requested alongside antigenic C1 inhibitor (see C1 esterase inhibitor – antigenic) and C3 and C4. This test aids diagnosis of type II HAE, affecting 15 % of sufferers. A low C4, plus a normal or raised C1 inhibitor antigenic level, is associated with low/absent C1 inhibitor functional activity. In type I HAE, patients have a low C1 inhibitor antigenic level and low functional activity.
Recurrent angioedema, laryngeal oedema, or abdominal pain in the absence of urticaria Family history
|Sample & container required||Plain tube (Rust; Serum)|
|Sample volume||1 mL serum|
|Transport storage||For external users, separate and freeze immediately. Transport frozen.
For internal users, transport to I&I ASAP
|Turnaround time||21 days|