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HelpTest Code COMC3 Complement C3, Serum
Additional Codes
| Mayo Test ID |
|---|
| C3 |
Reporting Name
Complement C3, SUseful For
Assessing disease activity in systemic lupus erythematosus
Investigating an undetectable total complement (CH50) level
Method Name
Nephelometry
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Reference Values
75-175 mg/dL
Day(s) Performed
Monday through Friday
CPT Code Information
86160
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C3 | Complement C3, S | 4485-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C3 | Complement C3, S | 4485-9 |
Clinical Information
The complement system is an integral part of the body's immune defenses. It can be activated via immune complexes (classic pathway) or by bacterial polysaccharides (alternative pathway).The primary complement pathway consists of recognition (Clq, Clr, Cls), activation (C4, C2, C3), and attack (C5, C6, C7, C8, C9) mechanisms with respect to their role in antibody-mediated cytolysis.
C3 activation involves cleavage by C3 convertase into C3a and C3b. When immune complexes are not involved, the alternate method of complement activation initiates the reactant sequence at C3, bypassing C1, C4, and C2.
Severe recurrent bacterial infections occur in patients with homozygous C3 deficiency and in those patients with low levels of C3 secondary to the absence of C3b activator.
Decreased C3 may be associated with acute glomerulonephritis, membranoproliferative glomerulonephritis, immune complex disease, active systemic lupus erythematosus, septic shock, and end-stage liver disease.
Interpretation
A decrease in C3 levels to the abnormal range is consistent with disease activation in systemic lupus erythematosus.
Cautions
The results are dependent on appropriate specimen transport and storage.
Method Description
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)