Complement component 3, often called C3, is an essential protein of the immune system. This protein plays a vital role in the body’s innate immune system, providing the first line of defense against ...

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 ...

Many different lab tests are used to find changes in your body that can happen with lupus. The results of each test help your doctor get a fuller picture of your health. Because lab tests alone can’t ...

C3G and IC-MPGN can be difficult to diagnose because they are so rare and their symptoms are vague and nonspecific. A kidney biopsy is considered the gold standard and usually needed to confirm the ...