Clinical background:
This should be measured in cases of angioedema with low C4, when the total immunochemical C1-esterase inhibitor level is normal or high.
Specimen container paediatric:
Serum-Plain tube
Specimen container adult:
Serum-SST
Minimum volume paediatric:
2 ml
Minimum volume adult:
2 ml
Special requirements:
Samples MUST be separated within 4 hours of venesection. Please ensure that the sample arrives in the laboratory as soon as possible after being taken.
Sample stability:
Stored for 1 year at -80 degrees. Samples should not be freeze thawed prior to testing.
Freq analysis:
Fortnightly
Add on test:
Cannot be added on due to stability issues. Please discuss with the Protein Laboratory.
Quality assurance:
UK NEQAS for C1 Inhibitor and Functional ComplementINSTAND Complement EQA scheme
Interpretation:
Low levels are associated with HAE. However due to stability of C1 esterase inhibitor low levels should be discussed with Immunology.
Reference ranges:
Normal Adult Range: 70 -130% [expressed as % activity when compared to the control serum]
Other info:
Reported as a % of the activity of the control serum used in the assay.