Fourth Component of Complement
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C4 is decreased when classical pathway of complement is hyperactivated. It is usually decreased in hypergammaglobulinemia, cryoglobulinemia, inborn C4 deficiency, active SLE, serum sickness, SBE, chronic active hepatitis, acute glomerulonephritis and rheumatoid arthritis, as well as in hereditary angioneurotic edema.
Adult: 13-60 mg/dl
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.