C2 Complement, Functional, with Reflex, Serum
Use
This test is useful for the investigation of a patient with a low (absent) hemolytic complement activity. It includes reflex testing to C3 and C4 if the C2 result is less than 20 U/mL. C2 deficiency is the most common inherited complement deficiency and it is often associated with autoimmune disorders such as systemic lupus erythematosus (SLE), discoid lupus, dermatomyositis, glomerulonephritis, vasculitis, atrophoderma, cold urticaria, inflammatory bowel disease, and recurrent infections.
Special Instructions
The test requires a serum specimen, which should be collected in a serum gel or red top tube. After collection, the specimen should be placed on wet ice to clot, centrifuged at 4 degrees C, and serum aliquoted into a plastic vial. It must be frozen immediately within 30 minutes of centrifugation.
Limitations
Proper specimen handling is crucial to avoid activation of the complement system before testing. Gross hemolysis and gross lipemia are causes for specimen rejection. The test is not FDA-approved but is compliant with CLIA requirements. A normal total complement assay should be performed before ordering individual component assays to screen for suspected deficiencies.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 93977-7
- 93977-7
- 69048-7
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Serum gel or red top tube; submission in plastic vial
Collection Instructions
Immediately place on wet ice to allow clotting, centrifuge at 4°C, aliquot serum into a plastic vial, and freeze within 30 minutes.
Patient Preparation
Fasting for 12 hours is preferred but not required
Causes for Rejection
Gross hemolysis, gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 21 days |