What's this test for?

This test is ideal if you're experiencing unexplained blood clots, or if you have a family history of clotting disorders like deep vein thrombosis or pulmonary embolism. It's also useful if you've had recurrent miscarriages or unusual clotting at a young age, since these can sometimes point to a protein C deficiency. Testing helps figure out whether your body is making enough of this natural clot-preventing protein and whether it's working correctly.

What happens after I get my results?

Your results will show up in your account with each value's normal range clearly explained, so you can see exactly where you stand. If your activity level comes back low, the report will walk you through what a possible reflex to protein C antigen testing means and what steps typically come next. You can download a standard lab report straight from your account at any time, and if you retest down the road, the trends feature lets you track changes over time. If a result looks dangerously low or you have symptoms like sudden leg swelling or chest pain, seek medical care right away.

Who should consider this test?

Anyone with a personal or family history of unexplained blood clots, especially at a young age, should consider this test. It's also worth doing if you've had multiple miscarriages, a clot during pregnancy, or a strong reaction to blood-thinning medication that doesn't make sense. People starting or stopping certain anticoagulants may also want a baseline check, since some blood thinners can affect the results.

What symptoms indicate I may need this test?

Watch for signs like sudden swelling, pain, or warmth in one leg, unexplained shortness of breath, or chest pain — these can point to a blood clot. A rare skin condition called warfarin-induced skin necrosis, which causes painful dark patches after starting certain blood thinners, is also a red flag for protein C problems. If clots seem to run in your family or keep happening despite no clear cause, that's another reason to get checked.

When will I get my results?

Results are typically ready within about 7 days of your blood draw. This extra time is needed because the test may include a reflex step, where the lab automatically runs a follow-up antigen test if your initial activity result comes back low. You'll get a notification as soon as everything is ready to view in your account.

What is protein C and why does it matter?

Protein C is a natural protein made by your liver that helps control blood clotting by breaking down clot-promoting factors once they've done their job. Think of it as your body's built-in brake system for clotting — without enough of it, or if it doesn't work properly, blood can clot too easily or too often. Having the right amount and function of protein C helps protect you from dangerous clots in your veins.

What does low protein C activity mean?

Low protein C activity means your blood may not have the ability to slow down clotting the way it should, which raises your risk of blood clots forming in your veins. This can be something you're born with, or it can develop from things like liver disease, certain medications, or vitamin K issues. A low result usually leads to a follow-up antigen test to figure out exactly what's causing the low number.

What causes low protein C levels?

Low protein C can be inherited, meaning you were born with a gene that makes less of it or a faulty version of it. It can also be acquired from liver disease, vitamin K deficiency, certain blood thinners like warfarin, cancer, major surgery, trauma, or a serious clotting condition called DIC. Certain chemotherapy drugs can lower protein C levels too.

How often should I retest?

If you're on blood thinners like warfarin, timing matters a lot since these drugs can lower your results, so retesting is often done after being off the medication for a few weeks, when appropriate. If you had a normal result and no new symptoms, you likely don't need to repeat this test regularly. Anyone actively being monitored for a clotting disorder may need periodic retesting to track how their levels change over time.

What should I do if my results are abnormal?

If your protein C level comes back low, avoid starting or stopping any blood-thinning medication without guidance, since these can affect both your risk and future test results. Staying active, keeping a healthy weight, and avoiding long periods of sitting still can help lower your overall clotting risk. If you notice symptoms like leg swelling, pain, or sudden shortness of breath, seek medical care immediately rather than waiting for a routine follow-up.

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.

Protein C Activity Test - Clotting Disorder 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

[email protected]