A complement C4 (also known as a complement component 4, or simply C4) is a test to measure the level of C4 proteins you have in your blood. These proteins play a role in how your immune system ...

These findings suggest complement protein levels may be an important biomarker for type 1 diabetes. Disruption of the complement system appears to precede the onset of islet autoimmunity (IA), making ...

Complement 3 glomerulopathy (C3G) is a rare kidney disease that affects your body’s innate immune system (complement system). Complement 3 glomerulopathy (C3G) is a kidney disease that’s caused by ...