Home
HelpTest Code C4 Complement C4, Serum
Additional Codes
Sunquest: C4M
EPIC: LAB151
Reporting Name
Complement C4, SUseful For
Investigating an undetectable total complement (CH50)
Confirming hereditary angioedema (with low C1 inhibitor)
Assessing disease activity in systemic lupus erythematosus, proliferative glomerulonephritis, rheumatoid arthritis, and autoimmune hemolytic anemia
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
14-40 mg/dL
Day(s) Performed
Monday through Friday
CPT Code Information
86160
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C4 | Complement C4, S | 4498-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C4 | Complement C4, S | 4498-2 |
Clinical Information
The complement system is an integral part of the immune defenses. It can be activated via immune complexes (classic pathway) or by bacterial polysaccharides (alternative pathway). The classic complement pathway consists of recognition, (C1q, C1r, C1s), activation (C2, C3, C4), and attack (C5, C6, C7, C8, C9) mechanisms with respect to their role in antibody-mediated cytolysis. C4 is one of the activation proteins of the classic pathway.
In the absence of C4, immune complexes will not be cleared by C3 activation peptides, but bacterial infections can still be defended via the alternative pathway.
C4 may be decreased in systemic lupus erythematosus, early glomerulonephritis, immune complex disease, cryoglobulinemia, hereditary angioedema, and congenital C4 deficiency.
Specimen Retention Time
14 daysTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.