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. Complement component C3 is the most important and abundant protein in the complement system. 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 compliment 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 3 (C3) of the complement system. Deficiency of C3 may be associated with active Lupus, recurrent bacterial infections, and acute glomerulonephritis (a type of kidney disease caused by problems with your body’s immune system).1
Fasting is not required. Take all medications as prescribed.
Accessed March 2015