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Blood Test for Clotting Problems and Family History
Protein S Antigen, Free
- Checks blood clotting protein levels
- Measures protein that prevents clots
- Assesses risk of blood clots
$781
Example results
First results as soon as overnight*
90 day happiness guarantee
We stand behind our service
Prescription & fees included
Go directly to the lab, no extra fees
Easy to understand results
With friendly doctor's notes & guidance
Fast & convenient
Lab visit as quick as 10 mins in & out
90 day happiness guarantee
We stand behind our service
Prescription & fees included
Go directly to the lab, no extra fees
Easy to understand results
With friendly doctor's notes & guidance
Fast & convenient
Lab visit as quick as 10 mins in & out
What's this test for?
This test is ideal if you're experiencing unexplained blood clots, have a family history of clotting disorders, or have had multiple miscarriages. It helps identify whether you have low levels of Protein S, a natural blood thinner that prevents abnormal clot formation. Many people use this test when investigating recurrent deep vein thrombosis (DVT), pulmonary embolism, or stroke at a young age.
What's included in this test?
This test measures free Protein S Antigen, which is the active form of Protein S that works with Protein C to prevent your blood from clotting too easily. Low levels can indicate an inherited or acquired deficiency that increases your risk of developing dangerous blood clots in your legs, lungs, or other organs. This single measurement provides critical insight into your body's natural clot-prevention system.
What happens after I get my results?
You'll receive detailed doctor notes in simple language explaining what your Protein S levels mean for your clotting risk and overall health. These notes include personalized recommendations like lifestyle modifications, whether you need to avoid certain medications or hormones, and when to consider blood thinners or further evaluation. You'll also get the standard lab report and can track your Protein S levels over time using our trends feature, especially helpful if you're monitoring treatment or managing a known deficiency.
Who should consider getting this test?
This test is important for people who've had unexplained blood clots before age 50, recurrent clotting events, or clots in unusual locations. It's also recommended if you have a family history of blood clots, have experienced multiple miscarriages, or are planning to start hormone therapy or birth control pills. Anyone with a personal or family history of thrombosis should consider screening.
What symptoms indicate I may need this test?
Warning signs include swelling, pain, or redness in your legs (possible DVT), sudden shortness of breath or chest pain (possible pulmonary embolism), or unexplained stroke symptoms. You might also consider this test if you've had recurrent pregnancy losses or if blood relatives have experienced clotting problems. Sometimes there are no symptoms until a clot occurs, which is why family history is so important.
What is Protein S and why does it matter?
Protein S is a natural protein in your blood that acts like a brake on your clotting system, preventing clots from forming when they shouldn't. It works alongside Protein C to break down clotting factors and keep your blood flowing smoothly. When Protein S levels are too low, your blood can become too prone to clotting, increasing your risk of serious conditions like deep vein thrombosis, pulmonary embolism, or stroke.
What does low Protein S mean?
Low Protein S levels mean your blood may clot more easily than it should, putting you at higher risk for dangerous blood clots. This can be inherited from your parents or acquired due to conditions like liver disease, pregnancy, or certain medications. People with low Protein S may need to take preventive measures during high-risk situations like surgery, long flights, or pregnancy.
What causes low Protein S levels?
Low Protein S can be inherited as a genetic condition passed down through families, or it can be acquired. Common causes include pregnancy, taking birth control pills or hormone replacement therapy, liver disease, vitamin K deficiency, or certain autoimmune conditions. Acute blood clots themselves can temporarily lower Protein S levels, so retesting after recovery is often necessary for accurate results.
How often should I retest my Protein S levels?
If you're initially testing due to a recent blood clot, you should retest at least 6 weeks after the clotting event and when you're off blood thinners for accurate results. If you have a confirmed deficiency, periodic monitoring may be recommended by your doctor, especially during pregnancy or before starting hormone therapy. For those with normal levels and no symptoms, routine retesting isn't typically necessary unless circumstances change.
What should I do if my Protein S is low?
If your results show low Protein S, discuss the findings with a hematologist or your doctor who can determine if it's a true deficiency or temporary. You may need to avoid long periods of inactivity, stay well-hydrated, and be cautious with hormone-based medications. During high-risk situations like surgery or long flights, your doctor might recommend compression stockings or preventive blood thinners to reduce clotting risk.
How’s this work?
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 [email protected] and we'll gladly help you.
How do I know which test to get?
Just text or call us at 754-799-7833, email us at [email protected], and we'll gladly help you. We've got your back and reply quickly.
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?
Just reach out to us via text at 754-799-7833 or shoot us an email at [email protected]. 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?
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 [email protected].
Can I cancel my order?
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 [email protected].
You can read more about our cancellation policy here.
How can I find a lab location near me?
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 [email protected] and we'll gladly help you.
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Demo results
Protein S Antigen, Free
52%
Demo results
Low
Optimal 60 - 130
High
52%
What this means
Your free Protein S level is slightly below the optimal range, which may increase your risk of developing abnormal blood clots. While this is not an immediate emergency, it suggests your blood may clot more easily than ideal, especially during high-risk situations like long flights, surgery, or pregnancy.
Recommended actions
Stay well-hydrated and avoid prolonged periods of sitting or inactivity
Discuss your results with a hematologist to determine if this is hereditary or acquired
Avoid smoking and maintain a healthy weight to reduce additional clotting risk factors
Consider retesting in 6-8 weeks if recovering from illness or recent blood clot
* Regular blood test results (e.g., CBC) typically start arriving the next business day after sample collection. More complex tests, such as hormone panels, may take up to 10–15 business days due to their complexity.
Here’s how easy it is to get blood work done on your terms
Order your test
Save a trip to the doctor. Your results will come with clear, friendly explanations.
Takes 2 minutes
Book an appointment
Visit any of our 4,000 nearby lab locations to have your samples collected.
Book or walk-in
Get results
Receive a clear, easy-to-digest health report by email & SMS within a few business days.
Get answers, fast
Blood Test for Clotting Problems and Family History
- Checks blood clotting protein levels
- Measures protein that prevents clots
- Assesses risk of blood clots
$781
Example results
1,000,000+ blood tests later, here's what our customers say
3138 reviews
Still got questions?
Text our super-cool support team at 754-799-7833 to get help finding your ideal checkup.
