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Test Code C3 C3 Complement

Additional Codes

Epic: LAB152

Specimen Required

Specimen Type: Serum

Collection Container/Type: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 3 mL

Collection Instructions: Centrifuge and separate cells after clot formation and within 4 hours of collection.  

Specimen Minimum Volume

0.25 mL

Specimen Stability

Room temperature: Unacceptable

Refrigerated: 8 days

Frozen: 8 days

Reference Range


1 - 14 years: 80 - 170 mg/dL

>14 years: 82 - 185 mg/dL



1 - 14 years: 82 - 173 mg/dL

>14 years: 83 - 193 mg/dL

Rejection Due To

Unlabeled, mislabeled, wrong tube type, hemolyzed, visually lipemic, QNS, exceeds specimen/stability requirements.

Report Available

Same day

Clinical Significance

The Complement system is an integral part of the immune defenses.  Increased C3 levels are associated with acute phase reaction, rheumatic disease, viral hepatitis, myocardial infarction, cancer, diabetes, pregnancy, sarcoidosis, amyloidosis, thyroiditis, inflammatory bowel disease, typhoid fever, and pneumococcal pneumonia.  Decreased levels occur in individuals with congenital deficiency or immunologic diseases, particularly SLE, infective endocarditis and DIC.  The role of C3 in complement pathways results in patients with decreased levels being at risk for severe infection, particularly S. pneumoniae, H. influenzae and N. meningitis.

Method Name



Samples containing paraproteins (abnormal monoclonal antibodies) may incorrectly fall within the reference range. Samples with elevated total protein concentrations or suspected paraproteinemia can be screened with other methods such as electrophoresis.  Turbidity and particles in samples can interfere with the assay.  Therefore, particulate matter should be removed by centrifugation prior to running the assay.




Day(s) Performed