Complement C3

Complement C3 is a key protein in the immune system, which is part of the complement system. This system helps the body fight infections and clear away dead cells. C3 helps activate the immune response by binding to pathogens (like bacteria or viruses), triggering a cascade of other proteins that enhance the immune reaction.

Why consider this test?

The C3 serum test is conducted to assess immune function, particularly in inflammatory or autoimmune disorders. Low or high levels of C3 can indicate the presence of several conditions, including:

• Autoimmune Diseases: Conditions like lupus or rheumatoid arthritis, where the immune system attacks healthy tissues.
• Infections: Severe bacterial infections can lead to a depletion of complement proteins like C3.
• Kidney Diseases: Certain kidney diseases, like glomerulonephritis, can lower C3 levels.
• Liver Disease: Since C3 is produced in the liver, liver conditions might affect its production.

Who should get this test done?

This test may be recommended for:

• People suspected of having autoimmune diseases like lupus, rheumatoid arthritis, or vasculitis.
• Individuals with chronic infections that are not easily treated.
• Patients with kidney disorders (like nephritis or glomerulonephritis).
• People with unexplained recurrent infections.

More Information

C3 levels can vary depending on the age, sex, and overall health of the person being tested. The complement system works in a cascade, so if C3 levels are low, there may also be abnormal levels of other complement proteins like C4. However, this test alone is often not enough to diagnose a specific condition but is used as part of a broader diagnostic approach.