C9 Complement, Functional, Serum
Use
This test is used for diagnosing C9 deficiency and investigating patients with low total hemolytic complement levels. The complement system is critical to immune defense and involves multiple pathways, including the classical, alternative, and lectin pathways, which result in the formation of the membrane attack complex (MAC). Deficiency in late complement proteins like C9 can increase susceptibility to infections, particularly neisserial infections, though many C9 deficient patients can be asymptomatic.
Special Instructions
Fasting for 12 hours is preferred but not required before specimen collection. It is essential to handle the serum specimen properly to prevent complement activation before testing. If a refrigerated centrifuge is not available, use a room temperature centrifuge but keep the sample on ice before centrifugation and freeze immediately after aliquoting.
Limitations
Improper specimen handling can lead to complement activation, skewing results. Low or absent levels of functional C9 in the presence of normal C9 antigen levels may necessitate retesting to confirm that inactivation wasn't due to mishandling during shipping.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 87727-4
- 87727-4
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 collection, place the tube on wet ice and allow the specimen to clot. Centrifuge at 4 degrees C and aliquot serum into a plastic vial. Freeze the specimen within 30 minutes of centrifugation. If not frozen immediately, place on dry ice.
Patient Preparation
Fasting: 12 hours, preferred but not required
Causes for Rejection
Gross hemolysis or gross lipemia.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |