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. It's also useful if you've had a clot at a young age or in an unusual location, since these can be signs of an underlying clotting protein problem. Many people order this test after a clotting event to help understand what may have caused it.

What's included in this test?

This test measures both the activity and the amount of antithrombin, a protein that helps regulate blood clotting. Looking at both numbers together helps tell the difference between a protein that's simply low in quantity versus one that's present but not working correctly, which matters for understanding your clotting risk.

What happens after I get my results?

Your results will be available in your account, with each value's normal range clearly explained so you know exactly what your numbers mean. Depending on your levels, next steps might include retesting to confirm a low result, reviewing medications that could affect clotting proteins, or discussing lifestyle changes that support healthy circulation. A standard lab report is available to download directly from your account. You can also track your results over time using the trends feature, which is helpful if you're monitoring a known clotting risk.

Who should consider this test?

This test is a good fit for people who've had an unexplained blood clot, especially at a young age, or who have close family members with clotting disorders. It's also worth considering if you have a condition like liver disease, nephrotic syndrome, or sepsis, since these can lower antithrombin levels. People starting certain blood thinner medications may also want a baseline check.

What symptoms indicate I may need this test?

Watch for signs like swelling, pain, or warmth in one leg, which can point to a deep vein clot, or sudden shortness of breath and chest pain, which can signal a clot in the lungs. Recurring clots, especially without an obvious cause, are another key reason to test. If you experience severe or sudden symptoms like chest pain or difficulty breathing, seek emergency medical care right away rather than waiting for test results.

When will I get my results?

Results are typically ready within about 7 days of your sample being processed at the lab. You'll receive a notification once your report is available in your account, so there's no need to call or follow up.

How can I naturally support healthy blood clotting balance?

Staying well-hydrated and moving regularly, especially on long trips or after surgery, helps keep blood flowing normally and lowers clot risk. Maintaining a healthy weight and avoiding smoking are two of the most impactful lifestyle steps you can take. Some people also find that reducing prolonged sitting and elevating the legs periodically helps support healthy circulation, though these steps don't replace medical treatment for a known clotting disorder.

What does a low antithrombin result mean?

A low result means your body may have less of this protein or less of it working properly, which can raise the risk of forming blood clots. This can be something you're born with, or it can happen because of conditions like liver disease, certain infections, or use of specific medications. If your result is low, retesting and reviewing any related health conditions or medications is a reasonable next step.

What causes low antithrombin levels?

Low levels can be inherited, meaning you're born with a gene change that reduces how much antithrombin your body makes or how well it works. They can also be acquired, which is actually more common, and can result from liver disease, nephrotic syndrome, heparin therapy, sepsis, or certain chemotherapy drugs. Identifying whether the cause is inherited or acquired often requires looking at the pattern of activity versus antigen levels together.

How often should I retest antithrombin levels?

If your first result is low or unclear, retesting after any acute illness has resolved is a good idea, since conditions like infection or liver problems can temporarily lower levels. For ongoing monitoring, retesting every 6 to 12 months is common if you have a known deficiency or are being watched for clotting risk. Your trends data can help you and your care routine track whether levels are stable over time.

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 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 Activity and Antigen Blood Test

Antithrombin III Activity and 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?

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Antithrombin Activity and Antigen Blood Test

Prescription & all lab fees included

Doctor's guidance included

Fast & convenient

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