Skip to main content
Immunology Laboratory

This site is best viewed with a modern browser. You appear to be using an old version of Internet Explorer.

C1q Antibody and Levels

Please note: The C1Q Levels and Antibody testing assays are performed by a referral laboratory. This assay is only available to members of Oxford University Hospitals NHS Foundation Trust.

C1q is the initiating molecule for the classical activation pathway of complement. Deficiencies or defects in the molecule lead to a reduced or absent CH50 value. Familial deficiency is rare but reduced levels may be associated with SLE, recurrent bacterial infections and with glomerulonephritis. C1q levels are usually only measured in cases where CH50 is absent or the patient has increased susceptibility to infection. The exception to this is in the identification of the consumptive defect in acquired angioedema, where levels are almost always low. (Source:

This assay is performed at a referral laboratory (external users requiring serum C1Q levels are advised to contact the referral laboratory directly):

The Department of Immunology
PO Box 894
S5 7YT

Specimen requirements

Serum 1ml; plasma is NOT acceptable



Laboratory turnaround time

28 days

Laboratory method


Reference range/units

Anti-C1Q antibody (0-15) U/ml

C1Q Levels (50 – 250) mg/L

Associated tests


Shipping and storage

Internal hospital transport/courier.

Ensure delivery Monday to Friday 07:00 - 17:30.

Further information and contact details

For further information, email