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Complement C3

C3 Complement Component 3
Serum (SST) g/L

About this test

Most abundant complement protein. Consumed in active immune complex-mediated inflammation. Low C3 with low C4 and positive anti-dsDNA strongly supports lupus nephritis.

Reference Ranges

Sex Age Range Notes
All ≥ 18 yrs 0.9 – 1.8 Adult

Clinical Interpretation

Low / Decreased
Complement consumption — SLE (especially nephritis), infective endocarditis, membranoproliferative GN, sepsis.
High / Increased
Acute-phase response (C3 is also a positive acute-phase reactant).

Related Tests

Anti-dsDNA Complement C4
Specimen
Serum (SST)
Reporting Unit
g/L
Category
🛡️ Immunology

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.