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Test 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.


Useful 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, S

Specimen Type

Serum

Specimen 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.

Day(s) Performed

Wednesday

Report Available

2 to 8 days

Specimen Retention Time

2 weeks

Performing 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

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