Complement C4 is a protein involved in the classical pathway of the complement immune system. It plays a role in fighting infections and clearing immune complexes from the body.
Category: Inflammation & Immune
Also known as: complement c4, c4, c4 complement, serum c4
Reference range: 10–40 mg/dL (Source: ABIM)
Standard unit: mg/dL
High values may indicate
High C4 levels may indicate acute inflammation or infection, as C4 can act as an acute phase reactant.
Low values may indicate
Low C4 levels may indicate systemic lupus erythematosus (SLE), hereditary angioedema (C4 is often chronically low), immune complex disease, glomerulonephritis, or liver disease.