Name |
C1 Esterase Inhibitor (Function) |
Alternative name/Profile |
Hereditory Angioedema, CIF, C1-INH, CI, Complement |
Department |
Immunology |
Investigation |
Enzyme Immunoassay (ELISA) (MicroVue C1-lnhibitor EIA) |
Specimen type |
Clotted blood |
Sample type |
Serum |
Sample container & volume |
5ml Red |
Frequency of analysis |
Once every 2 weeks |
Turnaround time |
21 days |
Availability |
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Notes |
Useful for:
- Diagnosing Hereditory Angioedema in patients that have normal or elevated C1 Esterase Inhibitor levels.
Clinical Information:
- C1 Esterase Inhibitor inhibits C1 activation in the classical pathway of the complement cascade.
- A C1 Esterase Inhibitor deficiency results in inappropriate C1 activation leading to C2 and C4 breakdown. This can result in acute oedema of subcutaneous tissue, the gastrointestinal tract and/or the upper respiratory track.
- A C1 Esterase Inhibitor deficiency can be acquired or hereditory.
- The hereditory deficiency is an autosomal dominant condition.
- A functional C1 Esterase Inhibitor assay can be useful in the diagnosis of Hereditory Angioedema as 15% of hereditory C1 Esterase Inhibitor deficiencies are due to a non-functional C1 Esterase Inhibitor protein.
Please Note:
- Samples for C1 Esterase Inhibitor function must be spun down and frozen within 3 hours.
- Where External Institiutions cannot guarantee immediate delivery, samples must be centrifuged, separated and frozen within 3 hours of collection. Samples can then be transported, frozen on dry ice, to St. James's Hospital for processing.
- Samples for C1 esterase inhibitor function must be in the laboratory by 16:00 daily.
- A reduced or absent C1 esterase inhibitor function assay should be confirmed by repeating the assay on a fresh sample.
- To distinguish between hereditory and acquired C1 Esterase Inhibitor deficiency, C1q levels are required. Hereditory deficiencies will have normal C1q levels while acquired deficiencies will have low C1q levels.
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Related links |
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Reference range |
Abnormal/Absent <40%
Equivocal/reduced= 41-67%
Normal= >68%
Reference ranges sourced from http://immqas.org.uk;Immunology UK NEQAS and PRU handbook of Clinical Immunochemistry, 9th Edition, 2007. Last updated January 2013. |
Last updated |
Wed, 12 Jun 2024 12:45:52 IST |
