The complement system is a group of proteins that are important in your defense against infection and play a role in the development of inflammation.

There are nine major complement proteins called C1 through C9. These various components travel through your blood stream searching for foreign invaders such as bacteria or viruses. When this happens, the complement system is activated and works as a cascading event like the falling of a row of dominoes. Most of the time the outcome of compliment activation is favorable; the "foreign invader" is removed with no damage to cells or tissue. But in some people, the complement system activation becomes uncontrolled or certain components may be deficient causing autoimmune disease or the risk of recurrent mild or serious bacterial infections.

This blood test measures component 4 (C4) of the complement system. Deficiency of C4 is closely linked to development of autoimmune diseases such as lupus and rheumatoid arthritis.¹

Instructions

Fasting is not required. Take all medications as prescribed.

Note

For those following Dr. Shoemaker’s mold testing, this is testing C4 (ß1E Globulin), NOT C4a. He suggests using specifically Quest labs for C4a.

References

1. http://primaryimmune.org/about-primary-immunodeficiencies/specific-disease-types/complement-deficiencies/ Accessed March 2015