Complement Component 4
Also known as: C4
Use
Complement Component 4 (C4) is a significant part of the complement system, which plays a crucial role in the immune response. Testing for C4 levels may assist in ruling out a complement deficiency, which can be indicative of various immune disorders. Disorders such as hereditary angioedema, systemic lupus erythematosus, and other autoimmune conditions can show abnormal C4 levels, thus guiding diagnosis and treatment decisions.
Special Instructions
Specimens should be collected using a serum separator tube. Alternatively, lavender (EDTA), pink (K2EDTA), or green (lithium heparin) tubes are acceptable. Serum must be separated from cells as soon as possible or within two hours of collection. Transport should ensure the sample remains frozen to maintain its integrity.
Limitations
The test may not be informative if the specimen is improperly handled, such as being left to clot at refrigerated temperatures or exposed to repeated freeze/thaw cycles, which can degrade the sample. Additionally, while C4 testing is useful in identifying complement deficiencies, it may not fully diagnose underlying conditions without further clinical correlation and additional testing as some disorders may not exhibit altered C4 levels despite their pathological state.
New York Approved
Methodology
Immunoassay (Quantitative Immunoturbidimetry)
Biomarkers
LOINC Codes
- 4498-2
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.3 mL
Container
Serum separator tube. Also acceptable: Lavender (EDTA), pink (K2EDTA), or green (lithium heparin)
Collection Instructions
Allow specimen to clot at room temperature. Separate serum from cells ASAP or within 2 hours of collection and freeze.
Storage Instructions
Frozen
Causes for Rejection
Specimens left to clot at refrigerated temperature. Specimens exposed to repeated freeze/thaw cycles.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 8 days |
| Frozen | 3 months |