A few questions help us personalize your report.
Complement C4 is a key protein in the classical complement pathway, consumed when immune complexes activate the cascade. Persistently low C4 is a hallmark of hereditary angioedema and is frequently depressed in active systemic lupus erythematosus. C4 null alleles are present in up to 30% of the population and can cause false-positive low results.
Also known as: C4, C4 Complement, Complement C4, Complément C4, Complemento C4, 보체C4, 补体 C4, 补体C4
High C4 is a nonspecific acute-phase response. Low C4 is consumed in active lupus and cryoglobulinemia. Persistently low C4 raises suspicion for hereditary angioedema.
Standard range is 16-48 mg/dL. Optimal is 20-40 mg/dL. C4 null alleles are common in up to 30% of the population.