Autoimmune / Rheumatology
Also known as: Complement component 4
No common urgent flag from this test alone
This test checks how much C4 protein is in your blood. This protein is a part of your body's defense system. It helps your body fight off sickness and infections.
Doctors often order this test to help find or check on sicknesses where your body attacks itself. These include diseases like lupus or rheumatoid arthritis. The test can also help see if the medicines for these problems are working well.
Reference ranges for Complement C4 can vary by laboratory. Your doctor will interpret your results based on your individual health, symptoms, and other tests.
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.