What's this test for?

This test is ideal if you're experiencing unexplained blood clots or have a family history of clotting disorders. It helps figure out if your body is making enough Antithrombin III, a protein that helps keep your blood from clotting too much. It's also useful if you've had repeated miscarriages or a clot at a young age, since these can be signs of an inherited clotting problem.

What's included in this test?

This test starts with a measurement of Antithrombin III activity, and if that comes back low, it automatically reflexes to check the Antithrombin III antigen level too. Looking at both numbers together helps tell the difference between a protein that isn't being made in the right amount versus one that's present but not working correctly. This distinction matters because it affects whether the issue is inherited or caused by something else going on in the body.

What happens after I get my results?

Your results will show up in your account along with the normal range for Antithrombin III activity and antigen levels, explained in plain language. If your levels come back outside the normal range, next steps usually include retesting to confirm the result and looking at lifestyle factors like avoiding smoking and staying active, since these can affect clotting risk. A downloadable lab report is available in your account, and you can track your results over time using the trends feature. If your result suggests a serious clotting risk, seek medical care right away.

How can I naturally support healthy blood clotting balance?

Staying active with regular movement helps keep your blood circulating well and lowers clotting risk. Drinking enough water throughout the day, avoiding smoking, and maintaining a healthy weight also support normal clotting function. If you sit for long periods, like during travel, try to get up and move every hour or so to keep blood flowing.

When will I get my results?

Results are typically ready within about 7 days from when your sample is collected. You'll get a notification once they're posted to your account, where you can view the values along with what they mean. Because this test may involve an additional reflex step if your first result is low, it can sometimes take a bit longer to get the complete picture.

Who should consider this test?

People with a personal or family history of blood clots, especially at a young age or in unusual locations, should consider this test. It's also worth considering if you've had repeated pregnancy losses or a clot that happened without an obvious cause like surgery or long travel. People with liver disease or other conditions that can affect clotting proteins may also benefit from checking their levels.

What symptoms indicate I may need this test?

Watch for symptoms like swelling, pain, or warmth in one leg, which can be signs of a deep vein clot. Sudden shortness of breath or chest pain can indicate a clot has traveled to the lungs and needs urgent attention. A history of unexplained clots, especially if they run in your family, is also a good reason to get checked.

What does low Antithrombin III mean?

Low Antithrombin III means your body has less of this protective protein, which normally helps keep blood clotting in check. This can raise your risk of forming blood clots, whether from an inherited trait or from another condition like liver disease or a recent illness. Retesting and looking at your overall health picture helps clarify what's driving the low level.

What causes low Antithrombin III?

Low levels can be inherited, meaning you're born with a gene that limits how much of this protein your body makes or how well it works. They can also be acquired, from things like liver disease, kidney problems that cause protein loss, heparin use, or serious illnesses like sepsis. Certain chemotherapy drugs and conditions like disseminated intravascular coagulation (DIC) can also lower levels temporarily.

How often should I retest?

If your first result is abnormal, retesting is often recommended after any acute illness or medication effects have resolved, since these can temporarily change your levels. For ongoing monitoring, especially if you're on blood thinners or have a known clotting disorder, retesting every so often as advised helps track your levels over time. Using the trends feature in your account makes it easy to see how your results change.

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.

Antithrombin III Test - Blood Clot Risk 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]

Antithrombin III Blood Clot Risk Test

Antithrombin III Activity with Reflex to Antithrombin III Antigen

Prescription & all lab fees included

Doctor's guidance included

Fast & convenient

Prescription & all lab fees included

Doctor's guidance included

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.

Find a lab near you

Antithrombin III Blood Clot Risk Test

Prescription & all lab fees included

Doctor's guidance included

Fast & convenient

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