What's this test for?

This test is ideal if you're being treated with Tysabri (natalizumab) for multiple sclerosis and your symptoms seem to be returning or your treatment doesn't seem to be working as well as it used to. It checks whether your body has developed antibodies against the medication, which can make it less effective. It's also useful if you've had an infusion reaction and want to understand why.

What happens after I get my results?

Your results will show up in your account along with an explanation of what a positive or negative antibody result means. If antibodies are found, a common next step is retesting to confirm the result, since some antibodies are temporary and can disappear over time, while persistent antibodies may mean it's time to discuss a different treatment approach. You can download a standard lab report from your account at any time, and you'll be able to track this result over time using the trends feature if you test again in the future.

Who should consider this test?

Anyone currently taking Tysabri who has noticed their MS symptoms coming back, is having infusion reactions, or just wants to check whether the medication is still working well for them should consider this test. It's also useful for people who've been on Tysabri for a long time, since antibodies can develop even after months of stable treatment. Testing gives you concrete information instead of just guessing why symptoms changed.

What symptoms indicate I may need this test?

Returning MS symptoms like new numbness, vision changes, weakness, or balance problems while on Tysabri are a signal worth checking. Infusion reactions such as hives, itching, chest tightness, or flushing during or after treatment are another reason to test. If your treatment just doesn't feel like it's working the way it used to, that's also worth investigating.

When will I get my results?

Results are typically ready within about 7 days of your sample being collected. You'll get a notification when they're available, and you can log into your account to view them at that time. Turnaround can occasionally vary slightly depending on lab volume.

What is a natalizumab antibody and why does it matter?

A natalizumab antibody is a protein your immune system makes when it recognizes Tysabri as something foreign, kind of like how your body reacts to a virus. When these antibodies build up, they can block the drug from working properly or cause you to react to the infusion itself. Checking for them helps explain unexpected symptom flare-ups during treatment that would otherwise be confusing.

What does a positive antibody result mean?

A positive result means your immune system has made antibodies against Tysabri, which can reduce how well the medication controls your MS. This doesn't mean something is wrong with you — it's a known, fairly common reaction, happening in roughly 4.5% to 14.1% of people on this drug. It's a good idea to retest to confirm persistence before making any treatment decisions.

What causes these antibodies to develop?

Antibodies form simply because your immune system treats natalizumab as a foreign substance, similar to how it would respond to bacteria or a virus. Some people develop them early, within the first few months of treatment, while for others it takes longer or never happens at all. There's no specific lifestyle cause — it's an individual immune response that varies from person to person.

How often should I retest?

If you test positive, retesting around 3 months later is a common approach to see if the antibodies are transient (temporary) or persistent (long-term). If your first test is negative but you start having new symptoms or infusion reactions later, that's a good time to test again. Your infusion schedule and symptom pattern will help guide how often makes sense for you.

What should I do if my results are abnormal?

If your antibody test comes back positive, keep track of any symptoms you're having and consider a follow-up retest in a few months to check if the antibodies persist. Note the timing and severity of any infusion reactions, as this information is useful for deciding next steps with your treatment. If you experience a severe infusion reaction like difficulty breathing or chest tightness, seek medical care right away.

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.

Tysabri Antibody Test - MS Treatment Response 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

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