Why This Lab Is Important
+
Standard thyroid hormone testing does not always capture the full picture of thyroid health. In some individuals, hormone levels may appear normal while underlying issues such as impaired hormone conversion or autoimmune thyroid activity remain undetected. For a more complete evaluation of thyroid function, Dr. Passero recommends the Durable THYROID PREMIUM panel.*
This expanded panel builds on the Durable THYROID ESSENTIAL panel by measuring the core thyroid hormones—TSH, Free T4 and Free T3—while also including markers that evaluate thyroid hormone conversion and autoimmune thyroid activity. These added markers—Reverse T3, thyroid peroxidase antibodies and thyroglobulin antibodies—can provide deeper insight when symptoms persist despite otherwise normal thyroid hormone levels.*
Reverse T3 helps show whether your body is properly using thyroid hormones. The thyroid primarily produces T4, which is then converted into T3, the active hormone that controls metabolism. During this process, some T4 can instead turn into Reverse T3, an inactive form which does not support the metabolism. Elevated Reverse T3 levels can suggest your body is converting more T4 into this inactive form instead of the active T3 your body needs. This panel also includes thyroid antibodies (thyroid peroxidase and thyroglobulin antibodies), which help detect autoimmune thyroid conditions such as Hashimoto’s thyroiditis—one of the most common underlying causes of thyroid dysfunction.*
Dr. Passero recommends the Durable THYROID PREMIUM panel for anyone seeking to:*
What’s Included in the Durable THYROID PREMIUM Panel
This panel tests for the following key markers that influence thyroid health:*
What to Expect After Ordering Your Lab Test
After purchasing a lab test from Durable, you’ll receive an order confirmation right away. Your lab order will be emailed separately within two business days. All lab-related communications—including your lab order, instructions and results notifications—are sent via encrypted, HIPAA-compliant email from labs@livedurable.com. To ensure timely delivery, we recommend adding this address to your contacts and checking your spam or promotions folder.
Lab Locations
We've partnered with LabCorp and Quest Diagnostics for convenient blood draw locations nationwide. Once your lab order is emailed to you, it will designate the most convenient location based on your address. You should contact the lab directly to schedule an appointment, and we recommend having your blood draw performed within 2-4 weeks. If you have any concerns about the selected location, please email labs@livedurable.com to explore alternative options.
Timing of Results
Once your blood draw is complete, most results are available within one week. You’ll receive an email notification from labs@livedurable.com when your results are ready to review.
How to Interpret Results
All test results include a lab-generated reference range reflecting values commonly seen in a healthy population. Results are flagged only when they fall outside this range as high or low. While these reference ranges provide helpful context, results are best interpreted alongside your health history, symptoms and trends over time and should be reviewed with your healthcare practitioner.
If you are interested in a virtual lab review with Dr. Passero, you may email his office at GetHealthy@DrKevinPassero.com to schedule an appointment.
This expanded panel builds on the Durable THYROID ESSENTIAL panel by measuring the core thyroid hormones—TSH, Free T4 and Free T3—while also including markers that evaluate thyroid hormone conversion and autoimmune thyroid activity. These added markers—Reverse T3, thyroid peroxidase antibodies and thyroglobulin antibodies—can provide deeper insight when symptoms persist despite otherwise normal thyroid hormone levels.*
Reverse T3 helps show whether your body is properly using thyroid hormones. The thyroid primarily produces T4, which is then converted into T3, the active hormone that controls metabolism. During this process, some T4 can instead turn into Reverse T3, an inactive form which does not support the metabolism. Elevated Reverse T3 levels can suggest your body is converting more T4 into this inactive form instead of the active T3 your body needs. This panel also includes thyroid antibodies (thyroid peroxidase and thyroglobulin antibodies), which help detect autoimmune thyroid conditions such as Hashimoto’s thyroiditis—one of the most common underlying causes of thyroid dysfunction.*
Dr. Passero recommends the Durable THYROID PREMIUM panel for anyone seeking to:*
- Go beyond standard thyroid testing to evaluate hormone conversion and autoimmune thyroid activity
- Investigate persistent symptoms such as fatigue, brain fog or weight changes despite normal thyroid hormone levels
- Monitor thyroid health more comprehensively over time
What’s Included in the Durable THYROID PREMIUM Panel
This panel tests for the following key markers that influence thyroid health:*
- TSH (Thyroid Stimulating Hormone)—TSH is the hormone that signals the thyroid to produce T4 and T3. Changes in TSH often serve as the body’s first warning sign that the thyroid might not be functioning optimally. TSH rises when the thyroid is not producing enough hormone and lowers when thyroid hormone production becomes excessive.
- Free T4 (Free Thyroxine)—Free T4 measures the active form of thyroxine, the primary hormone produced by the thyroid. Much of T4 must be converted into T3, the more active hormone used at the cellular level. Measuring Free T4 helps assess overall thyroid hormone production and availability.
- Free T3 (Free Triiodothyronine)—Free T3 measures the active form of thyroid hormone that the body uses to regulate metabolism, energy and many core cellular functions. T3 is produced in smaller amounts by the thyroid and is also converted from T4. Measuring Free T3 helps assess whether the body has enough active thyroid hormone to support normal metabolic function.
- Reverse T3 (rT3)—Reverse T3 is an inactive form of thyroid hormone created during the conversion of T4. Unlike T3, it does not activate metabolism. Elevated reverse T3 levels may indicate that the body is converting thyroid hormone into this inactive form rather than producing the active T3 needed for normal metabolic function. Measuring reverse T3 can provide insight into thyroid hormone conversion patterns that may contribute to symptoms associated with reduced thyroid activity.
- Thyroid Peroxidase Antibodies (TPO)—TPO antibodies are immune proteins that target thyroid peroxidase, an enzyme the thyroid uses to produce hormones. Elevated levels may indicate autoimmune activity affecting the thyroid and are most commonly associated with Hashimoto’s thyroiditis, a condition in which the immune system gradually damages thyroid tissue.
- Thyroglobulin Antibodies (TgAb)—Thyroglobulin antibodies target thyroglobulin, a protein used by the thyroid gland to store and produce hormones. Measuring TgAb provides additional insight into autoimmune thyroid activity and can help identify immune involvement that may not always be detected through TPO antibodies alone.
What to Expect After Ordering Your Lab Test
After purchasing a lab test from Durable, you’ll receive an order confirmation right away. Your lab order will be emailed separately within two business days. All lab-related communications—including your lab order, instructions and results notifications—are sent via encrypted, HIPAA-compliant email from labs@livedurable.com. To ensure timely delivery, we recommend adding this address to your contacts and checking your spam or promotions folder.
Lab Locations
We've partnered with LabCorp and Quest Diagnostics for convenient blood draw locations nationwide. Once your lab order is emailed to you, it will designate the most convenient location based on your address. You should contact the lab directly to schedule an appointment, and we recommend having your blood draw performed within 2-4 weeks. If you have any concerns about the selected location, please email labs@livedurable.com to explore alternative options.
Timing of Results
Once your blood draw is complete, most results are available within one week. You’ll receive an email notification from labs@livedurable.com when your results are ready to review.
How to Interpret Results
All test results include a lab-generated reference range reflecting values commonly seen in a healthy population. Results are flagged only when they fall outside this range as high or low. While these reference ranges provide helpful context, results are best interpreted alongside your health history, symptoms and trends over time and should be reviewed with your healthcare practitioner.
If you are interested in a virtual lab review with Dr. Passero, you may email his office at GetHealthy@DrKevinPassero.com to schedule an appointment.
Lab-Specific FAQs
+
What does the Durable THYROID PREMIUM panel test for?
TSH, Free T4, Free T3, Reverse T3, Thyroid Peroxidase Antibodies and Thyroglobulin Antibodies.*
Do I need to fast or follow any special instructions prior to this test?
No, the Durable THYROID PREMIUM panel does not require fasting prior to testing.*
Are there any medications or supplements I should not take before my test?
If you take thyroid medication, you should wait until after the blood draw to take your daily dose. You may continue taking other prescribed medications unless your healthcare practitioner advises otherwise. Most supplements may be taken as usual prior to testing; however, supplements containing the B vitamin biotin should be discontinued 48-72 hours before thyroid testing, as biotin may interfere with results.*
Will recent diet or alcohol intake affect my results?
No. Short-term dietary choices or alcohol intake do not significantly influence the markers included in this panel.*
How often should I get this test?
Dr. Passero recommends routine monitoring of these markers, with testing every 3-6 months for most adults. Re-testing at the recommended interval allows you and your healthcare practitioner to monitor trends over time, assess how your body is responding to lifestyle or nutritional changes and make informed adjustments. Testing frequency should be individualized based on risk factors, clinical context and your doctor’s recommendations.*
Does insurance cover the cost of my tests?
Lab tests must be paid for in full at checkout using a credit card, a supported payment platform (such as Shop Pay, PayPal, Google Pay or Venmo), or an eligible FSA/HSA debit card. In some cases, health insurance providers may reimburse individuals for lab testing. You can contact your insurance provider directly to determine whether reimbursement is available. Please note that Durable is unable to provide insurance paperwork or assist with claim submission.
Can I get a refund if I choose not to get my lab work?
Yes. You may request a refund within 365 days of purchase, as long as you have not visited the lab and had your blood drawn.
Can I use a coupon when purchasing my lab test?
At this time, promotions and coupons cannot be applied to lab testing. Lab pricing reflects the cost of clinical testing and processing, and discounts are not available for these services. However, you can redeem Durable REWARDS points at checkout, and when you purchase a lab order, you’ll earn additional points.
Is this blood test for adults only?
Durable lab testing is intended for adults 18 years and older. Testing for individuals under 18 is only recommended when directed by a qualified healthcare provider.*
TSH, Free T4, Free T3, Reverse T3, Thyroid Peroxidase Antibodies and Thyroglobulin Antibodies.*
Do I need to fast or follow any special instructions prior to this test?
No, the Durable THYROID PREMIUM panel does not require fasting prior to testing.*
Are there any medications or supplements I should not take before my test?
If you take thyroid medication, you should wait until after the blood draw to take your daily dose. You may continue taking other prescribed medications unless your healthcare practitioner advises otherwise. Most supplements may be taken as usual prior to testing; however, supplements containing the B vitamin biotin should be discontinued 48-72 hours before thyroid testing, as biotin may interfere with results.*
Will recent diet or alcohol intake affect my results?
No. Short-term dietary choices or alcohol intake do not significantly influence the markers included in this panel.*
How often should I get this test?
Dr. Passero recommends routine monitoring of these markers, with testing every 3-6 months for most adults. Re-testing at the recommended interval allows you and your healthcare practitioner to monitor trends over time, assess how your body is responding to lifestyle or nutritional changes and make informed adjustments. Testing frequency should be individualized based on risk factors, clinical context and your doctor’s recommendations.*
Does insurance cover the cost of my tests?
Lab tests must be paid for in full at checkout using a credit card, a supported payment platform (such as Shop Pay, PayPal, Google Pay or Venmo), or an eligible FSA/HSA debit card. In some cases, health insurance providers may reimburse individuals for lab testing. You can contact your insurance provider directly to determine whether reimbursement is available. Please note that Durable is unable to provide insurance paperwork or assist with claim submission.
Can I get a refund if I choose not to get my lab work?
Yes. You may request a refund within 365 days of purchase, as long as you have not visited the lab and had your blood drawn.
Can I use a coupon when purchasing my lab test?
At this time, promotions and coupons cannot be applied to lab testing. Lab pricing reflects the cost of clinical testing and processing, and discounts are not available for these services. However, you can redeem Durable REWARDS points at checkout, and when you purchase a lab order, you’ll earn additional points.
Is this blood test for adults only?
Durable lab testing is intended for adults 18 years and older. Testing for individuals under 18 is only recommended when directed by a qualified healthcare provider.*
Durable THYROID PREMIUM Panel®
Dr. Passero recommends this expanded thyroid panel to evaluate TSH, Free T4 and Free T3, along with Reverse T3 and thyroid antibodies—helping uncover autoimmune thyroid activity and hormone conversion issues that may contribute to persistent symptoms.*
Suggested Frequency: Every 3-6 Months
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Why This Lab Is Important
+
Standard thyroid hormone testing does not always capture the full picture of thyroid health. In some individuals, hormone levels may appear normal while underlying issues such as impaired hormone conversion or autoimmune thyroid activity remain undetected. For a more complete evaluation of thyroid function, Dr. Passero recommends the Durable THYROID PREMIUM panel.*
This expanded panel builds on the Durable THYROID ESSENTIAL panel by measuring the core thyroid hormones—TSH, Free T4 and Free T3—while also including markers that evaluate thyroid hormone conversion and autoimmune thyroid activity. These added markers—Reverse T3, thyroid peroxidase antibodies and thyroglobulin antibodies—can provide deeper insight when symptoms persist despite otherwise normal thyroid hormone levels.*
Reverse T3 helps show whether your body is properly using thyroid hormones. The thyroid primarily produces T4, which is then converted into T3, the active hormone that controls metabolism. During this process, some T4 can instead turn into Reverse T3, an inactive form which does not support the metabolism. Elevated Reverse T3 levels can suggest your body is converting more T4 into this inactive form instead of the active T3 your body needs. This panel also includes thyroid antibodies (thyroid peroxidase and thyroglobulin antibodies), which help detect autoimmune thyroid conditions such as Hashimoto’s thyroiditis—one of the most common underlying causes of thyroid dysfunction.*
Dr. Passero recommends the Durable THYROID PREMIUM panel for anyone seeking to:*
What’s Included in the Durable THYROID PREMIUM Panel
This panel tests for the following key markers that influence thyroid health:*
What to Expect After Ordering Your Lab Test
After purchasing a lab test from Durable, you’ll receive an order confirmation right away. Your lab order will be emailed separately within two business days. All lab-related communications—including your lab order, instructions and results notifications—are sent via encrypted, HIPAA-compliant email from labs@livedurable.com. To ensure timely delivery, we recommend adding this address to your contacts and checking your spam or promotions folder.
Lab Locations
We've partnered with LabCorp and Quest Diagnostics for convenient blood draw locations nationwide. Once your lab order is emailed to you, it will designate the most convenient location based on your address. You should contact the lab directly to schedule an appointment, and we recommend having your blood draw performed within 2-4 weeks. If you have any concerns about the selected location, please email labs@livedurable.com to explore alternative options.
Timing of Results
Once your blood draw is complete, most results are available within one week. You’ll receive an email notification from labs@livedurable.com when your results are ready to review.
How to Interpret Results
All test results include a lab-generated reference range reflecting values commonly seen in a healthy population. Results are flagged only when they fall outside this range as high or low. While these reference ranges provide helpful context, results are best interpreted alongside your health history, symptoms and trends over time and should be reviewed with your healthcare practitioner.
If you are interested in a virtual lab review with Dr. Passero, you may email his office at GetHealthy@DrKevinPassero.com to schedule an appointment.
This expanded panel builds on the Durable THYROID ESSENTIAL panel by measuring the core thyroid hormones—TSH, Free T4 and Free T3—while also including markers that evaluate thyroid hormone conversion and autoimmune thyroid activity. These added markers—Reverse T3, thyroid peroxidase antibodies and thyroglobulin antibodies—can provide deeper insight when symptoms persist despite otherwise normal thyroid hormone levels.*
Reverse T3 helps show whether your body is properly using thyroid hormones. The thyroid primarily produces T4, which is then converted into T3, the active hormone that controls metabolism. During this process, some T4 can instead turn into Reverse T3, an inactive form which does not support the metabolism. Elevated Reverse T3 levels can suggest your body is converting more T4 into this inactive form instead of the active T3 your body needs. This panel also includes thyroid antibodies (thyroid peroxidase and thyroglobulin antibodies), which help detect autoimmune thyroid conditions such as Hashimoto’s thyroiditis—one of the most common underlying causes of thyroid dysfunction.*
Dr. Passero recommends the Durable THYROID PREMIUM panel for anyone seeking to:*
- Go beyond standard thyroid testing to evaluate hormone conversion and autoimmune thyroid activity
- Investigate persistent symptoms such as fatigue, brain fog or weight changes despite normal thyroid hormone levels
- Monitor thyroid health more comprehensively over time
What’s Included in the Durable THYROID PREMIUM Panel
This panel tests for the following key markers that influence thyroid health:*
- TSH (Thyroid Stimulating Hormone)—TSH is the hormone that signals the thyroid to produce T4 and T3. Changes in TSH often serve as the body’s first warning sign that the thyroid might not be functioning optimally. TSH rises when the thyroid is not producing enough hormone and lowers when thyroid hormone production becomes excessive.
- Free T4 (Free Thyroxine)—Free T4 measures the active form of thyroxine, the primary hormone produced by the thyroid. Much of T4 must be converted into T3, the more active hormone used at the cellular level. Measuring Free T4 helps assess overall thyroid hormone production and availability.
- Free T3 (Free Triiodothyronine)—Free T3 measures the active form of thyroid hormone that the body uses to regulate metabolism, energy and many core cellular functions. T3 is produced in smaller amounts by the thyroid and is also converted from T4. Measuring Free T3 helps assess whether the body has enough active thyroid hormone to support normal metabolic function.
- Reverse T3 (rT3)—Reverse T3 is an inactive form of thyroid hormone created during the conversion of T4. Unlike T3, it does not activate metabolism. Elevated reverse T3 levels may indicate that the body is converting thyroid hormone into this inactive form rather than producing the active T3 needed for normal metabolic function. Measuring reverse T3 can provide insight into thyroid hormone conversion patterns that may contribute to symptoms associated with reduced thyroid activity.
- Thyroid Peroxidase Antibodies (TPO)—TPO antibodies are immune proteins that target thyroid peroxidase, an enzyme the thyroid uses to produce hormones. Elevated levels may indicate autoimmune activity affecting the thyroid and are most commonly associated with Hashimoto’s thyroiditis, a condition in which the immune system gradually damages thyroid tissue.
- Thyroglobulin Antibodies (TgAb)—Thyroglobulin antibodies target thyroglobulin, a protein used by the thyroid gland to store and produce hormones. Measuring TgAb provides additional insight into autoimmune thyroid activity and can help identify immune involvement that may not always be detected through TPO antibodies alone.
What to Expect After Ordering Your Lab Test
After purchasing a lab test from Durable, you’ll receive an order confirmation right away. Your lab order will be emailed separately within two business days. All lab-related communications—including your lab order, instructions and results notifications—are sent via encrypted, HIPAA-compliant email from labs@livedurable.com. To ensure timely delivery, we recommend adding this address to your contacts and checking your spam or promotions folder.
Lab Locations
We've partnered with LabCorp and Quest Diagnostics for convenient blood draw locations nationwide. Once your lab order is emailed to you, it will designate the most convenient location based on your address. You should contact the lab directly to schedule an appointment, and we recommend having your blood draw performed within 2-4 weeks. If you have any concerns about the selected location, please email labs@livedurable.com to explore alternative options.
Timing of Results
Once your blood draw is complete, most results are available within one week. You’ll receive an email notification from labs@livedurable.com when your results are ready to review.
How to Interpret Results
All test results include a lab-generated reference range reflecting values commonly seen in a healthy population. Results are flagged only when they fall outside this range as high or low. While these reference ranges provide helpful context, results are best interpreted alongside your health history, symptoms and trends over time and should be reviewed with your healthcare practitioner.
If you are interested in a virtual lab review with Dr. Passero, you may email his office at GetHealthy@DrKevinPassero.com to schedule an appointment.
Lab-Specific FAQs
+
What does the Durable THYROID PREMIUM panel test for?
TSH, Free T4, Free T3, Reverse T3, Thyroid Peroxidase Antibodies and Thyroglobulin Antibodies.*
Do I need to fast or follow any special instructions prior to this test?
No, the Durable THYROID PREMIUM panel does not require fasting prior to testing.*
Are there any medications or supplements I should not take before my test?
If you take thyroid medication, you should wait until after the blood draw to take your daily dose. You may continue taking other prescribed medications unless your healthcare practitioner advises otherwise. Most supplements may be taken as usual prior to testing; however, supplements containing the B vitamin biotin should be discontinued 48-72 hours before thyroid testing, as biotin may interfere with results.*
Will recent diet or alcohol intake affect my results?
No. Short-term dietary choices or alcohol intake do not significantly influence the markers included in this panel.*
How often should I get this test?
Dr. Passero recommends routine monitoring of these markers, with testing every 3-6 months for most adults. Re-testing at the recommended interval allows you and your healthcare practitioner to monitor trends over time, assess how your body is responding to lifestyle or nutritional changes and make informed adjustments. Testing frequency should be individualized based on risk factors, clinical context and your doctor’s recommendations.*
Does insurance cover the cost of my tests?
Lab tests must be paid for in full at checkout using a credit card, a supported payment platform (such as Shop Pay, PayPal, Google Pay or Venmo), or an eligible FSA/HSA debit card. In some cases, health insurance providers may reimburse individuals for lab testing. You can contact your insurance provider directly to determine whether reimbursement is available. Please note that Durable is unable to provide insurance paperwork or assist with claim submission.
Can I get a refund if I choose not to get my lab work?
Yes. You may request a refund within 365 days of purchase, as long as you have not visited the lab and had your blood drawn.
Can I use a coupon when purchasing my lab test?
At this time, promotions and coupons cannot be applied to lab testing. Lab pricing reflects the cost of clinical testing and processing, and discounts are not available for these services. However, you can redeem Durable REWARDS points at checkout, and when you purchase a lab order, you’ll earn additional points.
Is this blood test for adults only?
Durable lab testing is intended for adults 18 years and older. Testing for individuals under 18 is only recommended when directed by a qualified healthcare provider.*
TSH, Free T4, Free T3, Reverse T3, Thyroid Peroxidase Antibodies and Thyroglobulin Antibodies.*
Do I need to fast or follow any special instructions prior to this test?
No, the Durable THYROID PREMIUM panel does not require fasting prior to testing.*
Are there any medications or supplements I should not take before my test?
If you take thyroid medication, you should wait until after the blood draw to take your daily dose. You may continue taking other prescribed medications unless your healthcare practitioner advises otherwise. Most supplements may be taken as usual prior to testing; however, supplements containing the B vitamin biotin should be discontinued 48-72 hours before thyroid testing, as biotin may interfere with results.*
Will recent diet or alcohol intake affect my results?
No. Short-term dietary choices or alcohol intake do not significantly influence the markers included in this panel.*
How often should I get this test?
Dr. Passero recommends routine monitoring of these markers, with testing every 3-6 months for most adults. Re-testing at the recommended interval allows you and your healthcare practitioner to monitor trends over time, assess how your body is responding to lifestyle or nutritional changes and make informed adjustments. Testing frequency should be individualized based on risk factors, clinical context and your doctor’s recommendations.*
Does insurance cover the cost of my tests?
Lab tests must be paid for in full at checkout using a credit card, a supported payment platform (such as Shop Pay, PayPal, Google Pay or Venmo), or an eligible FSA/HSA debit card. In some cases, health insurance providers may reimburse individuals for lab testing. You can contact your insurance provider directly to determine whether reimbursement is available. Please note that Durable is unable to provide insurance paperwork or assist with claim submission.
Can I get a refund if I choose not to get my lab work?
Yes. You may request a refund within 365 days of purchase, as long as you have not visited the lab and had your blood drawn.
Can I use a coupon when purchasing my lab test?
At this time, promotions and coupons cannot be applied to lab testing. Lab pricing reflects the cost of clinical testing and processing, and discounts are not available for these services. However, you can redeem Durable REWARDS points at checkout, and when you purchase a lab order, you’ll earn additional points.
Is this blood test for adults only?
Durable lab testing is intended for adults 18 years and older. Testing for individuals under 18 is only recommended when directed by a qualified healthcare provider.*
