What's this test for?

This test is ideal if you're experiencing joint pain, skin rashes, or ongoing unexplained hives that won't go away. It measures a marker of immune system activity that's often linked with autoimmune conditions like lupus and rheumatoid arthritis. It can also help figure out what's driving chronic hives when combined with other symptoms.

What's included in this test?

This test measures C4d, a byproduct that shows up when a specific part of your immune system (called the classical complement pathway) gets activated. This matters because elevated activity in this pathway is often seen in autoimmune conditions and certain types of chronic hives, so it helps narrow down what might be going on.

What happens after I get my results?

Your results will show up in your account with a clear explanation of what's considered a normal range for this marker. If your value is outside the normal range, next steps typically involve retesting alongside other immune markers to get a fuller picture, and making a plan for symptom tracking in the meantime. A standard lab report is available to download directly from your account. You can also use the trends feature to watch how this marker changes if you test again in the future.

How can I naturally support immune system balance?

Getting enough sleep, managing stress, and eating an anti-inflammatory diet rich in vegetables, fruits, and omega-3 fats can help support a balanced immune system. Regular moderate exercise and staying hydrated also play a role in reducing overall inflammation. Avoiding known triggers like excess alcohol, smoking, and highly processed foods can help too. These habits won't replace testing, but they support your body while you look into the underlying cause.

When will I get my results?

Results are typically ready within about 7 days of your lab visit. You'll get a notification when your report is ready to view in your account. If anything looks urgent, don't wait for a scheduled follow-up—seek medical care right away.

Who should consider this test?

This test is a good fit for people with symptoms like joint pain, unexplained rashes, or chronic hives that have lasted more than six weeks. It's also useful if you already have a diagnosed autoimmune condition and want to track immune activity over time. Anyone trying to understand whether their symptoms are linked to immune system overactivation may benefit.

What symptoms indicate I may need this test?

Common symptoms include joint pain or swelling, skin rashes (especially ones that worsen in sunlight), unexplained fatigue, and hives that keep coming back without an obvious cause. Some people also notice mouth sores or hair thinning alongside these symptoms. If these sound familiar, this test can help clarify what's happening beneath the surface.

What does a high C4d result mean?

A high C4d result usually means your immune system's classical complement pathway is more active than normal, which is commonly seen in autoimmune conditions like lupus or certain types of chronic hives. It doesn't diagnose a specific condition on its own, but it's a useful piece of the puzzle. Retesting and looking at your symptoms together with this value gives the clearest picture.

What causes abnormal C4d levels?

Abnormal levels are most often linked to autoimmune activity, like lupus or rheumatoid arthritis, where the immune system mistakenly attacks the body's own tissues. Chronic hives with an immune component can also drive this marker up. Infections and other inflammatory conditions can sometimes affect the result as well.

How often should I retest?

If you're actively managing symptoms or a known autoimmune condition, retesting every 3-6 months can help track changes over time. If your first result was in the normal range and symptoms improve, you may not need to retest right away. Use the trends feature in your account to keep an eye on any shifts.

Getting your blood test with us is easy, private & backed by the power of science.Long story short: In the test options, use the filters or search box to narrow your choices and find the test you want. If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test. Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout. If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want. When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system. Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way. You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy! If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.

How do I know which test to get?

In the test options, find the test you want. If you’re not sure which test to get, we can lend a hand in finding the right option. Just text or call us at 754-799-7833, email us at support@privatemdlabs.com, and we'll gladly help you. We've got your back and reply quickly.

When will my lab results be available?

Most test results will be available within 1–3 business days. Once they're ready, we'll send an email and text message to let you know. After your blood draw, just hang tight and don't worry – we'll keep you updated and in the loop! If you have any further questions, please text us at 754-799-7833 or email support@privatemdlabs.com, and we'll gladly help you.

Is it possible to make changes to my lab order if I made a mistake with the name, date of birth, or any other details?

Absolutely! We totally understand that errors can happen. No worries, we're here to help you. Just reach out to us via text at 754-799-7833 or shoot us an email at support@privatemdlabs.com. Remember to include your order number and let us know the correct information you’d like to update. Our awesome team will jump right in and make sure everything is sorted out and accurate for you. There are no changes necessary if your address is wrong on the requisition though. We don’t mail anything out. Our lab requires an address to be listed to generate an order.

Do you accept health insurance?

Only HSA & FSA is accepted. Our services are strictly self-pay and cannot be submitted to your health insurance provider except for Health Savings Accounts or Flexible Savings Accounts. This policy applies to all insurance companies, including federal health insurance programs like Medicare. If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com.

Can I cancel my order?

Yes. We get it – sometimes your needs change. As long as your samples haven’t been collected yet, we’re happy to help you cancel your order. If you have any further questions, please text us at 754-799-7833 or email support@privatemdlabs.com. You can read more about our cancellation policy here.

How can I find a lab location near me?

During the ordering process, you’ll be able to select a specific lab near you, with no strings attached! You can switch it up later easily and visit any of our authorized locations as long as it’s the same lab company you selected your test for (Quest Diagnostics or Labcorp). Before you proceed with your order, feel free to browse through all our lab locations here. This will give you the peace of mind of knowing that there's a lab nearby your home, office or your favorite gym. If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.

C4d Fragment Test - Autoimmune & Hives Screening

Getting your blood test with us is easy, private & backed by the power of science.

Long story short:

In the test options, use the filters or search box to narrow your choices and find the test you want.
If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test.
Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout.
If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want.
When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system.
Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way.
You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy!

754-799-7833

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