C5 Complement, Functional, Serum
Use
The test is used for diagnosing C5 deficiency and investigating patients with an undetectable total complement level. C5 plays a crucial role in the complement system, which is part of the innate immune system and involves pathways activated by immune complexes, leading to inflammation, phagocytosis, and cell lysis. Deficiencies in late complement proteins, including C5, can result in increased susceptibility to infections, particularly neisserial infections.
Special Instructions
Proper specimen handling is critical to prevent activation of the complement system before testing. A total complement assay should be used initially to screen for complement deficiencies before ordering component assays. If specimen handling issues occur leading to absence of or low C5 functional levels, replicate the test with a new serum sample to confirm results.
Limitations
This test has not been cleared or approved by the FDA but is consistent with CLIA requirements. Rare cases may require a functional assay as some proteins could be present but nonfunctional. Specimen stability and handling are crucial for accurate results, and caution should be taken to prevent complement activation during collection and processing.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 60472-8
- 60472-8
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 the specimen to clot. Centrifuge at 4 degrees C and aliquot serum into a plastic vial. Freeze specimen within 30 minutes of centrifugation. If not frozen immediately, the specimen must be placed on dry ice.
Patient Preparation
Fasting: 12 hours, preferred but not required
Storage Instructions
Serum samples should be frozen.
Causes for Rejection
Gross hemolysis, Gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |