COMPLEMENT C4 Detail

The Complement C4 Test evaluates the concentration of complement component 4 (C4) in the blood. C4 is a vital protein of the classical complement pathway, which is part of the immune system's defense mechanism against infections and in the clearance of immune complexes and damaged cells.

Low C4 levels are often associated with:

• Systemic Lupus Erythematosus (SLE)

• Hereditary angioedema (HAE)

• Autoimmune nephritis

• Immune complex-related diseases

High C4 levels may indicate inflammation, acute infections, or certain cancers, but are less clinically significant than low levels.

C4 testing is frequently done in conjunction with C3 testing, especially in patients with suspected lupus or glomerulonephritis. Persistently low levels of C4 may indicate ongoing immune system activation and disease activity.