Autoimmune / Rheumatology
Also known as: complement antigen, compliment activity C3, C4
No common urgent flag from this test alone
This test checks how much of a protein called C3 is in your blood. C3 is an important part of your body's defense system. It helps your body fight off sickness and germs.
Your doctor might order this test to help find or check on problems where your body's defense system attacks itself. This includes diseases like lupus and rheumatoid arthritis. The test can also help find certain infections caused by bacteria, viruses, or fungi.
Reference ranges for Complement C3 can vary between different laboratories. Your results should always be interpreted by your healthcare provider, considering your age, sex, pregnancy status, and overall health.
Clinical Reference
175932200080307Medicare covers for therapeutic drug monitoring
Educational purposes only — This information is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss your lab results with your healthcare provider.