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HelpTest Code C341Q Complement C3 and C4 with Anti-C1q Antibodies, Serum
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial
Useful For
Evaluating patients with suspected anti-C1q vasculitis
Predicting renal involvement in patients with systemic lupus erythematosus
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| C3 | Complement C3, S | Yes | Yes |
| C4 | Complement C4, S | Yes | Yes |
| AC1Q | Anti-C1q Antibodies, IgG, S | Yes | Yes |
Method Name
AC1Q: Enzyme-Linked Immunosorbent Assay (ELISA)
C3, C4: Nephelometry
Reporting Name
C3 and C4 with Anti-C1q, IgG, SSpecimen Type
SerumSpecimen Minimum Volume
0.9 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 21 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Reference Values
C3:
75-175 mg/dL
C4:
14-40 mg/dL
AC1Q:
<20 U/mL (Negative)
20-39 U/mL (Weak Positive)
40-80 U/mL (Moderate Positive)
>80 U/mL (Strong Positive)
Interpretation
A positive result for anti-C1q antibodies may support a diagnosis of anti-C1q vasculitis or renal involvement in patients with systemic lupus erythematosus in the appropriate clinical context.
A negative result indicates no detectable IgG antibodies to C1q and does not rule out a diagnosis.
A decrease in C3 levels to the abnormal range is consistent with disease activation in systemic lupus erythematosus.
Day(s) Performed
C3, C4: Monday through Friday
AC1Q: Wednesday
Report Available
2 to 8 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86160 x2
83520
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C341Q | C3 and C4 with Anti-C1q, IgG, S | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C3 | Complement C3, S | 4485-9 |
| C4 | Complement C4, S | 4498-2 |
| AC1Q | Anti-C1q Antibodies, IgG, S | 44702-9 |