C1 Esterase Inhibitor concentration and functional level

C1 (esterase) inhibitor level/function is decreased in hereditary/genetic and acquired angioedema. In Type I C1 inhibitor and acquired C1 inhibitor deficiency the protein level is decreased. In Type II C1 inhibitor deficiency where the protein is synthesised but non-functional its concentration is normal but functional C1 inhibitor activity is decreased. C1 inhibitor deficiency is associated with decreased complement C4 level.
The investigation of hereditary angioedema includes the determination of C1 inhibitor concentration and when indicated functional activity and C4 levels.
Reference range: 

Functional level >84
C1 inhibitor concentration 0.22 - 0.38

Functional level - %, Concentration level - mg/l
Sample type and Volume required: 
Clotted (Gold top Vacutainer)
Turnaround time: 
10 working days
Special sample instructions: 

All tests are compromised by prolonged transit times. For this reason, date of bleed and date of postage must be provided with each request.

Storage and transport: 
Sample must arrive in Immunology within 2 hrs, or for outside laboratories be separated and frozen within 2 hours and sent on ice.
Time limit for extra tests: 
10 days
Diagnostic Immunology and Allergy Department at King's College Hospital
General Enquiry : 020 3299 8752 / 020 3299 1171
King's College Hospital
Bessemer Wing - 1st Floor
Denmark Hill
London SE5 9RS
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 07/03/2017