Assay

C3 nephritic factor 

Key Words

C3 nephritic factor , C3NF

Specimen Collection

Serum (Brown)

The sample must be separated and frozen within 60 mins to prevent falsely low function results.

Please contact the Immunology laboratory (01733 678454) to make us aware that you are sending a sample for this test. (Monday to Friday ONLY)

Turnaround time

10 days

This test is referred to another centre:

Protein Reference Unit & Immunology Department

Laboratory Medicine Building

North Lane

Northern General Hospital

Herries Road

Sheffield

S5 7AU

0114 226 9196

Test indications

The test is only indicated if C3 concentrations are below the normal range, and are unexplained, and the C4 is within the reference range.

C3 nephritic factor is an IgG autoantibody which binds to the Bb portion of C3 convertase (C3bBb), thereby stabilising the molecule and preventing the action of Factor H. This results in the continual activation of the alternative complement pathway.

The presence of C3 nephritic factor has been observed in a variety of disorders; including membranoproliferative glomerulonephritis, post-streptococcus glomerulonephritis, partial lipodystrophy, SLE, urticarial vasculitis, with hypocomplementemia being a common feature.

This assay will not be performed if C3 is within the normal range.

Methodology

Immunoelectrophoresis

Interferences

Contact referral lab

Reference Range

N/A

Analytical error

Contact referral lab

Reference change value

N/A