A normal or elevated C4 effectively excludes the possibility of C1 esterase inhibitor deficiency, so no further analyses will be undertaken in such cases
Also known as C1 inactivator, this acute phase protein exhibits a deficiency in association with hereditary angioedema (angioneurotic oedema).
This skin condition is characterised by a few deep, large swellings which may be tender and often itch. There are two variations: Type 1 (85%) in which the actual production of the protein is decreased to between 5 – 30% of normal, and Type 2 (15%) in which the amount of protein is normal, but its functional activity is impaired or absent. Samples received for C1 esterase inhibitor will initially be analysed for C3 and C4. If the C4 is low, the sample will be sent to a Regional Assay Laboratory for determination of C1 esterase inhibitor mass and activity. In 15% of subjects with a “deficiency”, the inhibitor mass is normal, but its activity is impaired or absent.
A normal or elevated C4 effectively excludes the possibility of C1 esterase inhibitor deficiency, so no further analyses will be undertaken in such cases.
Can be added on to an existing request up to 4 days following sample receiptSpecimen Labelling Procedure