Complement C1q, Serum
Use
This test is useful for the assessment of an undetectable total complement level, diagnosing congenital C1 deficiency, and diagnosing acquired deficiency of C1 inhibitor. The first component of the complement (C1) is composed of 3 subunits designated as C1q, C1r, and C1s. C1q binds to immunoglobulin complexed to antigen and initiates the complement cascade. Congenital deficiencies of early complement components result in an inability to clear immune complexes, often leading to increased incidence of immune complex diseases.
Special Instructions
C1 deficiency is rare but is associated with increased incidence of diseases such as systemic lupus erythematosus and polymyositis. It is recommended to centrifuge and aliquot serum into a plastic vial for the test.
Limitations
This is a different assay from C1q binding. Low levels of C1q have also been noted in patients with abnormal immunoglobulin levels due to increased catabolism. The interpretation of results should consider the differential presence of normal levels of other complement factors like C2, C3, and C4.
New York Approved
Methodology
Automated Analyzer (Nephelometry)
Biomarkers
LOINC Codes
- 4478-4
- 4478-4
Result Turnaround Time
2-5 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
Centrifuge and aliquot serum into a plastic vial.
Patient Preparation
Fasting: 12 hours, preferred but not required.
Causes for Rejection
Gross lipemia: Reject
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 21 days |
| Refrigerated | 28 days |
| Frozen | 28 days |