C3 Nephritic Factor, Serum
Use
C3 Nephritic Factor (C3NeF) is an autoantibody that stabilizes the alternative complement pathway’s C3 convertase. Its presence leads to persistent activation of C3 and decreased C3 levels, commonly associated with membranoproliferative glomerulonephritis, dense‑deposit disease, partial lipodystrophy, and certain complement consumption disorders. It is typically ordered when complement C3 levels are low and helps clarify underlying complement system dysregulation.
Special Instructions
Refer to Quest forwarding the specimen to National Jewish Health (send‑out). Serum must be collected in a red‑top (no additive) tube, not an SST tube. The specimen must be frozen immediately after separation. Do not use serum separator tubes. Ensure proper volume for testing and submit on the Tuesday setup day.
Limitations
Specimens in SST tubes or thawed specimens are unacceptable. Room temperature or refrigerated specimens are unacceptable; frozen storage is required. The test is semi‑quantitative, functional assay by immunofixation, and is referral‑based—subject to availability of reference lab (National Jewish Health). Interpretation limited to presence/function, not quantitative C3 measurement.
Methodology
Immunoassay (Immunofixation)
Biomarkers
Result Turnaround Time
16 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1‑2 mL serum
Minimum Volume
0.5 mL serum
Container
Red Top (No Additive)
Collection Instructions
Collect blood in a red top tube; do not use SST tube; centrifuge and aliquot serum, freeze within 2 hours.
Causes for Rejection
SST tube; thawed specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unacceptable |
| Refrigerated | Unacceptable |
| Frozen | Indefinitely |