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Complement tests, most commonly C3 and C4, are used to determine whether deficiencies or abnormalities in the complement system are causing, or contributing to, a patient's disease or condition. The complement system is a group of proteins that move freely through your bloodstream. When immune complexes form, complement helps to clear them from the blood, temporarily decreasing complement levels. Decrease levels are seen in patients with SLE, Endocarditis & DIC. Congenital defficiency of C3, C4 increases the risk for recurrent bacteremia.
Complement testing may be ordered to help diagnose the cause of recurrent microbial infections, angioedema, or inflammation. It may be used to help diagnose and monitor the activity of acute or chronic autoimmune diseases such as systemic lupus erythematosus (SLE). It may be tested and monitored with immune complex-related diseases and conditions such as glomerulonephritis (a kidney disorder), serum sickness, rheumatoid arthritis, and vasculitis.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions.