Complement-4

Description

The Complement-4 (C4) test measures the level of complement component 4 in the blood. C4 is another important protein in the complement system of innate immunity. Like C3, low C4 levels can indicate ongoing complement activation or consumption. This test is often performed alongside C3 testing for a more comprehensive evaluation of complement function. It’s particularly useful in diagnosing and monitoring systemic lupus erythematosus (SLE), where low C4 levels often correlate with disease activity. C4 levels are also important in assessing hereditary angioedema, a rare genetic disorder. The test helps in differentiating between various autoimmune and immune complex disorders.