C8 Complement, Functional, Serum
Use
This test is useful for diagnosing C8 deficiency and investigating a patient with an undetectable total hemolytic complement level. Patients with deficiencies in the late complement proteins, such as C8, are unable to form the membrane attack complex, which can result in increased susceptibility to infections, particularly by Neisseria species. C8 deficiency is characterized by recurrent meningitis and autoimmune disease symptoms similar to systemic lupus erythematosus.
Special Instructions
Proper specimen handling is crucial to ensuring accurate results, as improper handling can activate the complement system before testing. The test uses a functional assay, which is recommended over antigen assays to detect cases where the protein is present but nonfunctional.
Limitations
Low or absent C8 functional levels in the presence of normal C8 antigen levels should be confirmed with a new serum specimen to ensure that C8 inactivation during shipping is not affecting results. The test is not FDA-cleared or approved; it was developed according to CLIA requirements.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 50997-6
- 50997-6
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
Plastic vial
Collection Instructions
Immediately after specimen collection, place the tube on wet ice and allow specimen to clot. Centrifuge at 4 degrees C and aliquot serum into a plastic vial within 30 minutes of centrifugation. Freeze specimen immediately; if not, use dry ice.
Patient Preparation
Fasting: 12 hours, preferred but not required
Causes for Rejection
Gross hemolysis, gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |