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Test Code C1ESRFUNCT C1q Complement, Functional, Serum


Specimen Required


Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Immediately after drawing the specimen, place the tube on wet ice.

2. Spin down and separate serum from clot.

3. Immediately freeze specimen.

Additional Information: Fasting preferred.


Useful For

Diagnosis of first component of complement (C1) deficiency

 

Investigation of a patient with an absent total complement (CH50) level

Method Name

Automated Liposome Lysis Assay

Reporting Name

C1Q Complement, Functional, S

Specimen Type

Serum Red

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Frozen 14 days

Clinical Information

Complement proteins are components of the innate immune system. There are 3 pathways to complement activation: 1) the classic pathway, 2) the alternative (or properdin) pathway, and 3) the lectin activation (or mannan binding protein, [MBP]) pathway. The classic pathway of the complement system is composed of a series of proteins that are activated in response to the presence of immune complexes. The activation process results in the generation of peptides that are chemotactic for neutrophils and that bind to immune complexes and complement receptors. The end result of the complement activation cascade is the formation of the lytic membrane attack complex.

 

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-C4) result in an inability to generate the peptides that are necessary to clear immune complexes and to attract neutrophils or generate lytic activity. These patients have increased susceptibility to infections with encapsulated microorganisms. They may also have symptoms that suggest autoimmune disease and complement deficiency may be an etiologic factor in the development of autoimmune disease.

 

Inherited deficiency of C1 is rare. C1 deficiency is associated with increased incidence of immune complex disease (systemic lupus erythematosus [SLE], polymyositis, glomerulonephritis, and Henoch-Schonlein purpura), and SLE is the most common manifestation of C1 deficiency. The SLE associated with C1 deficiency is similar to SLE without complement deficiency, but the age of onset is often prior to puberty.

 

Low C1 levels have also been reported in patients with abnormal immunoglobulin levels (Bruton's and common variable hypogammaglobulinemia and severe combined immunodeficiency), and this is most likely due to increased catabolism.

 

Complement levels can be detected by antigen assays that quantitate the amount of the protein. For most of the complement proteins a small number of cases have been described in which the protein is present but is non functional. These rare cases require a functional assay to detect the deficiency.

Reference Values

34-63 U/mL

Day(s) and Time(s) Performed

Monday through Saturday; Continuous with a 3 p.m. cutoff

Analytic Time

Same day/1 day

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

86161

LOINC Code Information

Test ID Test Order Name Order LOINC Value
C1QFX C1Q Complement, Functional, S 87722-5

 

Result ID Test Result Name Result LOINC Value
C1QFX C1Q Complement, Functional, S 87722-5

NY State Approved

Yes
Northwell Health Laboratories Additional Information:

Computer Interface Code

   PDM #  5902150