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HelpTest Code AC1Q Anti-C1q Antibodies, IgG, 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: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Secondary ID
621511Useful For
Evaluating patients with suspected anti-C1q vasculitis
Predicting renal involvement in patients with systemic lupus erythematosus
Detection of anti-C1q antibodies in serum
Method Name
Enzyme-Linked Immunosorbent Assay (ELISA)
Reporting Name
Anti-C1q Antibodies, IgG, SSpecimen Type
SerumSpecimen Minimum Volume
0.4 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 21 days | |
| Frozen | 21 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Clinical Information
Anti-C1q antibodies have been found to be prevalent in hypocomplementemic urticarial vasculitis syndrome (also referred to as anti-C1Q vasculitis) as well as in some patients with systemic lupus erythematosus (SLE)1,2. These antibodies occur more frequently in lupus nephritis, particularly during active disease. The main target clinical diseases include SLE and anti-C1Q vasculitis. Anti-C1q antibodies may also be seen in infectious diseases such as HIV and hepatitis C.
Reference Values
<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.
CPT Code Information
83520
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| AC1Q | Anti-C1q Antibodies, IgG, S | 44702-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| AC1Q | Anti-C1q Antibodies, IgG, S | 44702-9 |