What's this test for?

This test is ideal if you're experiencing frequent infections that seem harder to fight off than normal, unexplained inflammation, or have been diagnosed with an autoimmune condition like lupus. It measures two important proteins in your immune system (C3 and C4) that help your body fight infections and regulate inflammation. Many people use this test to understand why their immune system isn't working properly or to monitor autoimmune disease activity.

What happens after I get my results?

You'll receive detailed doctor notes in simple language explaining what your complement levels mean for your immune system health and inflammation. These notes include personalized recommendations about immune support, lifestyle adjustments, and whether you should follow up with a rheumatologist or immunologist. You'll also get the standard lab report and can track your complement levels over time using our trends feature, which is especially helpful for monitoring autoimmune disease activity.

What's included in this test?

This test measures Complement Component C3c and C4c. This test measures Complement Component C3c and C4c, two critical proteins in your immune system that work together to fight infections and control inflammation. C3 and C4 activate different immune pathways, and their levels can reveal whether your immune system is overactive (as in autoimmune diseases like lupus), underactive (making you prone to infections), or being consumed by ongoing inflammation. Together, these measurements help identify the root cause of immune system problems and monitor autoimmune disease progression.

Who should consider getting this test?

This test is important for people with recurrent or severe infections, those diagnosed with or suspected of having autoimmune diseases like systemic lupus or vasculitis, and anyone with unexplained chronic inflammation. It's also valuable for monitoring disease activity if you're already being treated for an autoimmune condition, or if your doctor suspects complement deficiency based on your symptoms.

What symptoms indicate I may need this test?

Common symptoms include getting sick frequently with infections that are hard to shake, unexplained joint pain and swelling, persistent fatigue, skin rashes (especially a butterfly-shaped rash on the face), or recurring kidney problems. You might also experience prolonged inflammation after minor illnesses or notice that cuts and infections take longer to heal than normal.

How can I naturally support my immune system?

Supporting immune health involves getting adequate sleep (7-9 hours nightly), managing stress through meditation or gentle exercise, and eating an anti-inflammatory diet rich in colorful fruits, vegetables, and omega-3 fatty acids from fish. Avoid smoking and excessive alcohol, stay hydrated, and consider vitamin D supplementation if levels are low. If you have an autoimmune condition, work with your healthcare provider on appropriate treatments while maintaining these healthy habits.

What is complement and why does it matter?

Complement is a system of proteins in your blood that acts like your immune system's alarm and attack system. When activated, these proteins work together to destroy harmful bacteria and viruses, trigger inflammation to heal damaged tissue, and clear out dead cells. When complement levels are too low, you can't fight infections well; when they're consumed too quickly by autoimmune activity, it signals your immune system is attacking your own body.

What does low C3 or C4 mean?

Low levels of both C3 and C4 typically suggest your immune system is actively fighting something, often seen in autoimmune diseases like lupus where the complement is being consumed faster than your body makes it. Low C3 alone (with normal C4) may indicate activation of a different immune pathway. Low levels can also mean you're not producing enough complement, making you more susceptible to infections.

What causes abnormal complement levels?

High complement consumption happens in autoimmune diseases (especially lupus and immune complex vasculitis), severe infections, and certain kidney diseases. Genetic complement deficiencies can cause persistently low levels from birth. Liver disease can also reduce complement production since the liver makes these proteins. Certain medications and chronic inflammation can affect levels as well.

How often should I retest my complement levels?

If you have active autoimmune disease like lupus, your doctor typically monitors complement levels every 3-6 months or more frequently during flares to track disease activity. If you're stable on treatment, testing every 6-12 months may be sufficient. For initial diagnosis or investigating frequent infections, your doctor may retest in 4-8 weeks to confirm findings or after addressing any underlying conditions.

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.

Immune System Test - Infections & Inflammation Check

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

[email protected]

Blood Test for Frequent Infections and Immune System Issues

Complement Component C3c and C4c

90 day happiness guarantee

Prescription & fees included

Easy to understand results

Fast & convenient

90 day happiness guarantee

Prescription & fees included

Easy to understand results

Fast & convenient

What's this test for?

What's included in this test?

What happens after I get my results?

Here’s why 1,000,000+ customers chose us for affordable hassle-free private blood testing.

Blood Test for Frequent Infections and Immune System Issues

90 day happiness guarantee

Prescription & fees included

Easy to understand results

Fast & convenient

1,000,000+ blood tests later, here's what our customers say