Complement C4

General information:

Each person's complement system consists of a group of important proteins in the blood. These proteins help the immune system fight harmful invaders such as viruses and bacteria and other foreign substances. There are nine major complement proteins, which are designated C1 through C9. C4 plays an important role in clearing some infections. The test measures the amount of complement C4 circulating in the blood. Low levels of C4 are associated with autoimmune diseases and collagen vascular diseases, such as lupus and rheumatoid arthritis. The C4 complement test is also sometimes used to monitor protein levels in people who have already been diagnosed with an autoimmune disease. Complement tests can provide doctors with valuable information about the effectiveness of current treatment for an autoimmune condition.

Sample required:

Venous blood

Key words:

complement C4