C1q Complement, Functional, Serum
Use
This test is used for the diagnosis of C1 deficiency, which may be indicated when a patient has an absent total complement level. Complement proteins are part of the innate immune system, serving as mediators for immune complex elimination and inflammatory processes. The deficiency of C1, specifically, can lead to increased susceptibility to infections and is associated with autoimmune conditions like systemic lupus erythematosus (SLE). Testing for C1q function helps determine the presence and level of active C1 protein in the serum, playing an important role in diagnosing primary immunodeficiencies and guiding the management of autoimmune conditions.
Special Instructions
For optimal results, it is recommended to conduct a total complement assay as a screening test for suspected deficiencies before ordering individual component assays. Fasting for 12 hours is preferred but not required prior to specimen collection.
Limitations
Proper specimen handling is crucial to avoid activation of the complement system before testing. Low or absent C1q levels require confirmation with a new specimen to rule out pre-analytical activation or degradation. Interference from improper handling, transport, or storage can affect the accuracy of results. Functional assays are necessary to identify non-functional complement proteins that might be present in normal quantities but do not function properly.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 87722-5
- 87722-5
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 on wet ice, allow to clot. Centrifuge at 4 degrees C, aliquot serum into a plastic vial, and freeze within 30 minutes. Must be placed on dry ice if not frozen immediately.
Patient Preparation
Fasting for 12 hours preferred but not required.
Causes for Rejection
Gross hemolysis, gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |