C4, Complement Component 4
C4 is one of the nine numbered proteins in the body’s complement system. Complement proteins support and strengthen the immune system so your body can fight off viruses, bacteria, and other germs. Low levels of C4 can be a risk factor for autoimmune diseases or recurrent infections.
The C4 Complement Blood Test results measure the levels of this protein in your blood.
This test can help detect and diagnose diseases including systemic lupus erythematosus (SLE), a chronic inflammatory disorder affecting joints, nerves, heart, skin, eyes, and other areas of the body. Other diseases that may require testing include serum sickness and chronic active hepatitis.
The test doesn’t require any special preparations for the blood draw.
Normal C4 levels are different for men (12 to 72 mg/dL) and women (13 to 75 mg/dL). If C4 complement is high, that can indicate inflammation-based diseases such as cancer or ulcerative colitis. Low C4 complement levels, on the other hand, may be a sign of infection, malnutrition, or hepatitis.
Based on your results, you may want to do more testing. You can measure levels of other individual proteins, as with a C3 test, or check all of them with a Complement Total (CH50) Blood Test. If your doctor wants to diagnose a specific issue such as hepatitis or cancer, we also offer several liver function and cancer screening tests to check for those diseases.
These results can be used to guide your treatment plan, so you can make lifestyle modifications or start medication as needed. If you want help analyzing these results, schedule a telehealth visit with one of our board-certified physicians.
Take a blood test for C4 complement near you, thanks to our 4,000-plus Labcorp or Quest Diagnostic partner labs across the country. With this wide-ranging network and streamlined ordering process, it’s never been easier to take control of your health.
Here’s how simple it is to get a C4 complement blood test:
Step 1: Purchase the test online and print out the lab order. (Depending on the state where you live, you may not even need a physician’s approval to get the test.)
Step 2: Find the facility closest to you with our lab locator and schedule the blood test.
Step 3: Get your blood drawn (be sure to bring the lab order with you to your appointment).
Step 4: You can find the results in your confidential Personalabs portal, typically within 2 to 10 business days. (Contact us if you need a specific turnaround time and we will reach out to the lab on your behalf, as times can vary by location.)
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