Epic Test Code LAB3752 Complement C1q, Serum
Additional Codes
MML Code: C1Q
NY State Approved
YesPerforming Laboratory
![](http://d3b6ik53zt4tlx.cloudfront.net/assets/performed-by-mcl.gif)
Reporting Name
Complement C1q, SMethod Name
Nephelometry
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 28 days | |
Frozen | 28 days | ||
Ambient | 21 days |
Specimen Required
Patient Preparation: Fasting for 12 hours
Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial
Blood Tube Draw Volume
Min 50% draw volume
- 50% of the tube fill volume is required for proper blood to additive ratio.
Specimen Type
SerumSpecimen Minimum Volume
0.5 mL
Reference Values
12-22 mg/dL
Report Available
2 to 5 daysDay(s) Performed
Monday through Friday
CPT Code Information
86160
Reject Due To
Gross hemolysis | OK |
Gross lipemia | Reject |
Gross icterus | OK |
Useful For
Assessment of an undetectable total complement (CH50) level
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Diagnosing congenital C1 (first component of complement) deficiency
Diagnosing acquired deficiency of C1 inhibitor
Clinical Information
The first component of complement (C1) is composed of 3 subunits designated as C1q, C1r, and C1s. C1q recognizes and binds to immunoglobulin complexed to antigen and initiates the complement cascade. Congenital deficiencies of any of the early complement components (C1, C2, C4) results in an inability to clear immune complexes. Inherited deficiency of C1 is rare.
Like the more common C2 deficiency, C1 deficiency is associated with increased incidence of immune complex disease (systemic lupus erythematosus, polymyositis, glomerulonephritis, and Henoch-Schonlein purpura). Low C1 levels have also been reported in patients with abnormal immunoglobulin levels (Bruton and common variable hypogammaglobulinemia and severe combined immunodeficiency). This is most likely due to increased catabolism.
The measurement of C1q is an indicator of the amount of C1 present.
Interpretation
An undetectable C1q in the presence of an absent total complement (CH50) and normal C2, C3, and C4 suggests a congenital C1 (first component of complement) deficiency.
A low C1q in combination with a low C1 inhibitor and low C4 suggests an acquired C1 inhibitor deficiency.
Cautions
This is a different assay than C1q binding, which is an assay for circulating immune complexes.