What's this test for?

This test is ideal if you're about to start a medication like azathioprine or mercaptopurine, which are commonly used for autoimmune conditions or certain cancers. It helps identify whether your body can safely process these drugs before you begin treatment. Knowing this ahead of time can help avoid severe, potentially dangerous reactions to standard doses.

What's included in this test?

This test looks at specific gene variants that control how well your body breaks down thiopurine medications. Understanding your genetic profile helps predict whether you'll process these drugs normally, slowly, or not at all, which is critical information before starting treatment.

What happens after I get my results?

Your results will be available in your account, along with an explanation of what your specific genotype means. If your results show reduced or deficient enzyme activity, the report will outline what that means for drug processing so you can discuss dosing adjustments before starting therapy. You can download a standard lab report from your account at any time, and since this is a one-time genetic result, there's no need for retesting or trend tracking like with other blood markers.

Who should consider this test?

Anyone who has been prescribed azathioprine, mercaptopurine, or thioguanine should consider this test before starting treatment. It's especially important for people being treated for autoimmune diseases, inflammatory bowel disease, or certain leukemias where these drugs are standard therapy. If you've had a bad reaction to these medications in the past, this test can help explain why.

When will I get my results?

Results are typically ready within about 7 days of your sample being processed at the lab. This timeframe reflects the specialized genetic testing methods needed to determine your specific gene variants. You'll be notified as soon as your results are available in your account.

What symptoms indicate I may need this test?

Since TPMT deficiency doesn't cause symptoms on its own, you won't feel anything different before starting medication. The real warning signs show up after starting a thiopurine drug, such as unusual bruising, unexplained bleeding, frequent infections, or extreme fatigue, which can signal your body isn't processing the drug properly. If you experience these symptoms after starting treatment, seek medical care right away.

What is TPMT and why does it matter?

TPMT stands for thiopurine S-methyltransferase, an enzyme that breaks down certain medications used to treat autoimmune conditions and some cancers. People with low or no TPMT activity can build up dangerously high levels of these drugs in their blood, even at normal doses. Testing your genotype ahead of time tells you and your care team how your body is likely to handle these medications.

What does a deficient or low-activity result mean?

A low or deficient result means your body breaks down thiopurine drugs much more slowly than average, which can cause the medication to build up to unsafe levels. This raises the risk of serious side effects like a dangerous drop in blood cell counts. This result typically means starting at a much lower dose or considering an alternative medication.

What causes reduced TPMT activity?

Reduced TPMT activity comes from inherited gene variants passed down from your parents, not from lifestyle or diet. About 11% of people in the US carry one variant copy, giving them intermediate activity, while roughly 1 in 300 people inherit two variant copies and have very low or no activity. This is a fixed genetic trait, so your result won't change over time.

Do I need to retest this in the future?

No, TPMT genotype is a fixed genetic trait that doesn't change throughout your life, so a single test result remains valid permanently. You won't need to repeat this test even if you're prescribed a different thiopurine medication later on. Keep a copy of your results handy for any future prescriptions involving these drugs.

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.

TPMT Genotype Test - Thiopurine Drug Safety 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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