Test Catalog

Test Id : C341Q

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Complement C3 and C4 with Anti-C1q Antibodies, Serum

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with suspected anti-C1q vasculitis

 

Predicting renal involvement in patients with systemic lupus erythematosus

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

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
A short description of the method used to perform the test

AC1Q: Enzyme-Linked Immunosorbent Assay (ELISA)

C3, C4: Nephelometry

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

C3 and C4 with Anti-C1q, IgG, S

Aliases
Lists additional common names for a test, as an aid in searching

C3 and C4 with Anti-C1q, IgG, S

Specimen Type
Describes the specimen type validated for testing

Serum

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

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

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

0.9 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
Frozen 21 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with suspected anti-C1q vasculitis

 

Predicting renal involvement in patients with systemic lupus erythematosus

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Anti-complement 1Q (C1Q) antibodies have been found to be prevalent in hypocomplementemic urticarial vasculitis syndrome (HUVS) (also referred to as anti-C1Q vasculitis) as well as in some patients with systemic lupus erythematosus (SLE).(1,2) These antibodies bind to the collagenous region of C1Q and activate the classic pathway of the complement system.(1,2) This is reflected in the serum by decreased circulating levels of classical pathway components C1Q and C4 as well as C3 seen in these diseases.(3,4) Therefore, testing for serum complement C3 and C4 biomarkers is important in the interpretation of anti-C1Q antibody results.(1-3)

 

Hypocomplementemic urticarial vasculitis (HUV) is a rare immune complex-mediated cutaneous vasculitis of small vessels characterized by recurrent episodes of wheal-like lesions and the presence of anti-C1Q antibodies.(3). In a French nationwide study, patients with HUV typically presented with low C1Q levels and normal C1 inhibitor levels, in association with anti-C1Q antibodies in 55% of cases.(5) As per the 2012 Revised International Chapel Hill Consensus Conference Nomenclature of Vasculitide, low complement levels and the presence of anti-C1Q antibodies distinguishes HUV from normocomplementemic UV (NUV), another form of UV.(6) Compared to NUV, HUV is associated with more severe disease and can indicate the presence of an underlying systemic disease such as SLE or HUVS.(7,8) In addition, HUVS is characterized by urticaria with hypocomplementemia, arthralgia/arthritis, glomerulonephritis, recurrent abdominal pain, and obstructive lung disease.

 

With respect to SLE, anti-C1Q antibodies together with anti-dsDNA antibodies, complement C3 and C4 may offer useful additional information to monitor lupus nephritis (LN) activity as well as patient’s overall disease activity status.(5,9,10) In a recent study, baseline levels of anti-C1Q and anti-dsDNA was reported to predict proliferative LN.(10) In this study, anti-C1Q antibodies was also a useful predictor of complete response at the time of kidney biopsy. Overall, the authors of the study concluded that tracking anti-C1Q autoantibodies over time may provide further insights into treatment response and pathogenic mechanisms in proliferative LN patients.

 

While the presence of anti-C1Q antibodies is considered useful in the evaluation and management of HUV and SLE, these antibodies may also be seen in several other autoimmune and infectious diseases. Therefore, all positive results must be interpreted in the context of patient’s clinical history and presentation.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

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
Provides information to assist in interpretation of the test results

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.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The results are dependent on appropriate specimen transport and storage.

 

A positive result for anti-C1q antibodies indicates they are detectable above the assay’s lower limit of quantitation and does not unequivocally establish any diagnosis.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Dragon-Durey MA, Blanc C, Marinozzi MC, van Schaarenburg RA, Trouw LA. Autoantibodies against complement components and functional consequences. Mol Immunol. 2013;56(3):213-221

2. Defendi F, Thielens NM, Clavarino G, Cesbron JY, Dumestre-Perard C. The immunopathology of complement proteins and innate immunity in autoimmune disease. Clin Rev Allergy Immunol. 2020;58(2):229-251

3. Marzano AV, Maronese CA, Genovese G, et al. Urticarial vasculitis: Clinical and laboratory findings with a particular emphasis on differential diagnosis. J Allergy Clin Immunol. 2022;149(4):1137-1149

4. Hristova MH, Stoyanova VS. Autoantibodies against complement components in systemic lupus erythematosus - role in the pathogenesis and clinical manifestations. Lupus. 2017;26(14):1550-1555

5. Jachiet M, Flageul B, Deroux A, et al. The clinical spectrum and therapeutic management of hypocomplementemic urticarial vasculitis: data from a French nationwide study of fifty-seven patients. Arthritis Rheumatol. 2015;67(2):527-534

6. Jennette JC, Falk RJ, Bacon PA, et al. 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. Arthritis Rheum. 2013;65(1):1-11

7. Mehregan DR, Hall MJ, Gibson LE. Urticarial vasculitis: a histopathologic and clinical review of 72 cases. J Am Acad Dermatol. 1992;26(3 Pt 2):441-448

8. Damman J, Mooyaart AL, Seelen MAJ, van Doorn MBA. Dermal C4d deposition and neutrophil alignment along the dermal-epidermal junction as a diagnostic adjunct for hypocomplementemic urticarial vasculitis (anti-C1q vasculitis) and underlying systemic disease. Am J Dermatopathol. 2020;42(6):399-406

9. Marto N, Bertolaccini ML, Calabuig E, Hughes GR, Khamashta MA. Anti-C1q antibodies in nephritis: correlation between titres and renal disease activity and positive predictive value in systemic lupus erythematosus. Ann Rheum Dis. 2005;64(3):444-448

10. Fava A, Wagner CA, Guthridge CJ, et al. Association of autoantibody concentrations and trajectories with lupus nephritis histological features and treatment response. Arthritis Rheumatol. Published online July 4, 2024. doi:10.1002/art.42941

Method Description
Describes how the test is performed and provides a method-specific reference

C3:

C3 is measured by immunonephelometry. Antiserum to C3 is mixed with patient serum, the light scatter resulting from the antibody interaction with C3 is measured, and the signal is compared to standard concentrations of C3.(Instruction manual: Siemens Nephelometer II Operations. Siemens, Inc; Version 2.4, 07/2019; Addendum to the Instruction Manual 2.3, 08/2017)

 

C4:

C4 is measured by immunonephelometry. Antiserum to C4 is mixed with patient serum, the light scatter resulting from the antibody interaction with C4 is measured, and the signal is compared to standard concentrations of C4.(Instruction manual: Siemens Nephelometer II Operations. Siemens, Inc; Version 2.4, 07/2019; Addendum to the Instruction Manual 2.3, 08/2017)

 

Anti-C1q antibodies, IgG:

Testing for antibodies to C1q is accomplished using a laboratory-developed immunoassay.(Unpublished Mayo method)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

C3, C4: Monday through Friday

AC1Q: Wednesday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 8 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

2 weeks

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

86160 x2

83520

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

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
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
C3 Complement C3, S 4485-9
C4 Complement C4, S 4498-2
AC1Q Anti-C1q Antibodies, IgG, S 44702-9

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
New Test 2024-10-01