Also known as: C3, C3 (β1C/β1A Globulin), C3 Complement.

The Complements are tested when you have recurrent microbial (usually bacterial) infections, unexplained inflammation or edema, or symptoms related to an autoimmune disorder; and to help monitor an acute or chronic condition that affects the complement system. Increased and decreased complement levels will not tell your health professional what is wrong, but they will give him an indication whether or not the immune system is involved with your condition. Complement levels can be increased with inflammation, rising before other markers such as the C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).