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Test Code C3NF C3 Nephritic Factor

Additional Codes

EPIC Order: Miscellaneous Lab Test (LAB000)

NJML test ID: C3NF

Performing Laboratory

National Jewish Medical Laboratory

Specimen Requirements

Patient Preparation: None

Container/Tube  
Preferred/Acceptable: Plain red-top tube
Collection Volume: 2.0 mL (minimum 1.0 mL)

Submission Container/Tube: If specimen is coming from outside facility aliquot processed sample into a plastic vial for transport. Place in dry ice to freeze immediately and send on dry ice.
Special Instructions: Send a completed "Advanced Diagnostic Laboratories National Jewish Health Complement Testing" requisition with specimen. Send specimen and req promptly to lab.

Sample Rejection

Mislabeled or unlabeled specimens

Specimen collected in gel tubes

Logistics

Test Availability: Monday-Sunday
Cut-off time: None

Days Set-up: Monday-Friday

Turnaround Time: 14 days

  • Note: additional testing time may be needed for less than perfect samples or confirmatory/reflex testing.

Reference Values

Reference Interval: 

Normal – Ratio is 0 – 0.26

Equivocal – Ratio is 0.27 – 0.33

Positive – Ratio is  > 0.34

INTERPRETATION: C3NF positivity could be a potential driver of complement alternative pathway dysregulation

Critical Values: None established

Methodology

Immunofixation Electrophoresis

Limitations

  • This is not a direct measurement of antibody quantity but only a qualitative (indirect) measure of its activity to produce C3b from full length C3.

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: Allow blood to clot at room temp (37o C) for 30-60 minutes. Centrifuge specimen to separate in refrigerated centrifuge at 4oC for 15 minutes. Immediately transfer cell-free serum into a 5-mL screw-capped plastic vial for transport. Place aliquot vial in dry ice to freeze immediately.
Processed Volume: 1.0 mL (minimum 0.5 mL) serum

Transport Temperature: Frozen
Analyte Stability:

Specimen Type Temperature Time
Whole Blood (unprocessed)  Ambient NA
Plasma/Serum (processed) Refrigerated    NA
  Ambient  NA
  Frozen @ -60o (preferred)    1 year       

NOTES:

  • Send frozen specimen direct to National Jewish by Priority Overnight on dry ice. Send Monday-Thursday only. Send the completed "National Jewish Complement Lab" requisition with specimen. 
  • Serum separator gel tubes are not acceptable, cancel if collected in SST tube.
  • If multiple tests are ordered on specimen for NJML, each test must have it's own aliquot tube.
  • Ambient temperature for centrifugation is acceptable provided that the time between collection and storage is minimized (approximately 60 minutes).

 

Test Classification and CPT Code

8616

LOINC

NA

Last Reviewed

10/2025