Complement

Complement is a group of proteins found in the blood and other body fluids. It plays an important role in the immune system by recognizing and targeting foreign substances, such as invading bacteria and other harmful substances.

Preparation for Complement Testing

No special preparation is needed for a complement test. Your doctor may request a fasting blood sample, which you should not eat or drink anything, except water, for several hours before the test.

Procedure for Complement Testing

Complement tests are usually performed in a hospital laboratory, where your blood will be collected and analyzed. The technician will draw a sample of your blood and separate the red and white blood cells from the clear fluid, known as serum. This is then further tested in a variety of ways, depending on the type of complement test being performed.

Types of Complement Testing

There are several different complement tests used to detect or measure the levels of complement proteins in the blood. These include the C3 and C4 test, CH50 test, and the CLASS test. Each of these tests measures a specific type of complement protein in the blood.

C3 and C4 Test: This test measures the amount of C3 and C4 proteins in the blood. C3 and C4 are needed to trigger the complement cascade, which is an inflammatory response that helps fight infection.
CH50 Test: This test measures the amount of an enzyme called CH50, which is released during an immune response. This enzyme helps activate the complement cascade and helps fight infection.
CLASS Test: This test is used to measure the concentrations of several different complement proteins, including C3, C4, and IgG. These proteins all play an important role in the body's response to infection.

Risks of Complement Testing

Complement testing is a safe and generally painless procedure. There is a slight risk of infection and bleeding from the needle prick used to draw a sample of your blood, but this risk is very low.

Why is Complement Testing Performed?

Complement testing is used to detect and measure the levels of complement proteins in the blood. It can help diagnose and monitor diseases and conditions that affect the immune system, such as lupus, rheumatoid arthritis, and other autoimmune disorders.

When is Complement Testing Performed?

Complement testing is typically ordered when a doctor suspects that there might be something wrong with a person's immune system. Your doctor may also order complement tests periodically to monitor autoimmune diseases, such as lupus, rheumatoid arthritis, and others.