Thyroid Panel
- Also Known As:
- Thyroid Function Panel
- Thyroid Test
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Test Quick Guide
The thyroid panel uses a blood sample to evaluate the functioning of the thyroid gland. A thyroid panel can help diagnose and monitor the treatment of thyroid disorders. As a panel test, the thyroid panel includes multiple measurements that can provide a detailed understanding of how well the thyroid gland is working.
About the Test
Purpose of the test
The thyroid panel is used to see how well the thyroid gland is functioning. The thyroid is responsible for producing hormones that are important for many bodily processes. Abnormal thyroid function, such as underactive thyroid (hypothyroidism) or overactive thyroid (hyperthyroidism), can lead to a wide range of symptoms. By measuring levels of thyroid hormones in the blood, the thyroid panel can help diagnose thyroid disorders and disrupted thyroid function.
A thyroid panel can also be used to monitor the treatment of hyperthyroidism and assess patients receiving levothyroxine therapy. Levothyroxine therapy replaces or supplements thyroid hormones that are reduced or absent due to hypothyroidism, thyroid cancer, thyroid nodules, and goiters.
What does the test measure?
The thyroid panel uses one blood sample to test for multiple elements related to thyroid function. Specifically, it measures the amounts of thyroid hormones and thyroid-stimulating hormones in the body.
Three hormones are part of a standard thyroid panel:
Finding a Thyroid Panel Test
How to get tested
A thyroid panel requires a blood sample. Laboratory testing involves using a needle to remove a small amount of blood from a vein in your arm. The procedure can happen in the doctor’s office, hospital, or another laboratory.
In most cases, a thyroid panel is ordered by a doctor. Sometimes the thyroid panel analysis is automatically done by the lab on the original blood sample if an initial evaluation finds abnormal levels of thyroid-stimulating hormone.
Can I take the test at home?
At-home thyroid test kits are commercially available without a prescription and measure the same hormones as the traditional thyroid panel.
For at-home testing, you prick your finger to get the necessary blood sample. That sample is then mailed to a laboratory that conducts the thyroid panel and makes the results available to you directly.
While at-home testing can measure thyroid levels, it is generally not a substitute for a test ordered by your doctor. If an at-home test detects abnormal thyroid levels, your doctor will likely recommend a new blood sample and thyroid panel to confirm the results. At-home tests for thyroid labs may not be as accurate as tests done in a laboratory.
How much does the test cost?
The cost of a thyroid panel depends on your insurance coverage and where the test is performed. If ordered by a doctor, insurance normally covers a thyroid panel except for any patient cost-sharing such as copays or deductibles. Check with your health plan and health care provider for specific cost details.
At-home thyroid tests usually cost less than $150, which includes the cost of shipping your blood sample to the lab.
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Taking the Thyroid Panel Test
The thyroid panel test is performed on a blood sample. If the test is being performed by a doctor, the blood sample comes from drawing blood from a vein with a needle.
If the test is being performed at home, the test kit typically contains a lancet, which pricks the finger to draw blood.
Before the test
No special preparation is required for the blood draw. In order to ensure the accuracy of the thyroid panel analysis, tell your doctor about any prescription or over-the-counter medications you are taking.
If you take thyroid hormone as treatment for thyroid disease, it is recommended that your blood sample be drawn before you take your dose for that day.
Tell your doctor if you are feeling sick before the test. The blood draw is usually postponed if you are ill or hospitalized because some illnesses can affect test results.
During the test
In a doctor’s office or lab, the blood sample for a thyroid panel will be taken by inserting a needle into a vein in your arm. A tourniquet may be used on your upper arm, and the puncture site will be disinfected before the blood is drawn.
You may experience a brief sting from the needle, but the pain is normally minimal and short-lived. The blood draw itself typically lasts less than a minute.
For at-home testing, you collect the blood sample after pricking one of your fingertips. A home test kit includes instructions for how to properly prepare this blood sample for the lab.
After the test
Once the blood draw is complete, a band-aid or cotton swab will be used to prevent bleeding. You will likely be instructed to keep this in place for an hour or more.
You can return to normal activities, including driving, once the test is over. You may be advised to avoid strenuous activity with your arm for a few hours after the test. If you notice any persistent pain, bleeding, or signs of infection, you should contact your doctor.
For fingerstick tests used in home testing kits, there are usually no limitations on activity after the test.
Thyroid Panel Test Results
Receiving test results
For both laboratory and in-home test kits, results are usually available within a few business days after the sample is received.
If your doctor ordered the test, you may have a follow-up appointment scheduled, or your doctor’s office may contact you by phone. Test results may also be available through an online health portal.
With home test kits, the results are made available to you through an online or mobile platform.
Interpreting test results
The results of your test will list the findings for each particular thyroid hormone. It may include reference ranges for normal results or indicate if your results in each category are normal or abnormal.
Reference ranges for each thyroid hormone differ based on a patient’s age, health status, and the laboratory that performs the testing. Reference ranges for each part of the thyroid panel used by the American Board of Internal Medicine are listed below:
- TSH: 0.5 to 4 mIU/L
- Free T4: 0.8 and 1.8 ng/dL in adults.
- Total T3: 80 to 180 ng/dL
Because this is a panel test, the results are generally interpreted together. Although TSH (thyroid stimulating hormone) is the primary indicator of thyroid function, free T4 and total T3 values help doctors understand the severity of thyroid disorders. Patients with normal TSH values may have abnormal T3 and/or T4 values that are associated with conditions unrelated to the thyroid.
The following table summarizes some examples of typical test results and their potential meaning for thyroid function.
| TSH | Free T4 | Total or Free T3 | Thyroid Function |
|---|---|---|---|
| Normal | Normal | Normal | Normal thyroid function |
| Normal | Normal or high | Normal or high | Normal thyroid function |
| Normal | Normal or low | Normal or low | Normal thyroid function |
| Normal | Low | Normal or high | Normal thyroid function |
| Normal | Low-normal or low | Normal or high | Normal thyroid function |
| High | Low | Normal or low | Primary hypothyroidism |
| High | Normal | Normal | Subclinical hypothyroidism |
| Low | High or normal | High | Hyperthyroidism |
| Low | Normal | Normal | Subclinical hyperthyroidism |
The thyroid panel is an important part of the diagnostic process but cannot alone conclusively diagnose a thyroid condition. With abnormal results, your doctor can best explain the specific findings and what they mean in your situation.
Sources and Resources
These resources provide additional information about thyroid tests and their role in health:
- MedlinePlus Medical Encyclopedia: Thyroid Diseases
- American Thyroid Association: Patient Information
- National Institute of Diabetes and Digestive and Kidney Diseases: Thyroid Tests
Sources
American Board of Internal Medicine. ABIM laboratory test reference ranges. Updated January 2021. Accessed June 29, 2021. https://www.abim.org/Media/bfijryql/laboratory-reference-ranges.pdf
National Institute of Diabetes and Digestive and Kidney Diseases. Thyroid tests. Updated May 2017. Accessed March 28, 2021. https://www.niddk.nih.gov/health-information/diagnostic-tests/thyroid
Ross D. Diagnosis of hyperthyroidism. In: Cooper DS, ed. UpToDate. Updated April 17, 2019. Accessed March 28, 2021. https://www.uptodate.com/contents/diagnosis-of-hyperthyroidism
Ross D. Euthyroid hyperthyroxinemia and hypothyroxinemia. In: Cooper DS, ed. UpToDate. Updated April 27, 2020. Accessed March 28, 2021. https://www.uptodate.com/contents/euthyroid-hyperthyroxinemia-and-hypothyroxinemia
Ross D. Laboratory assessment of thyroid function. In: Cooper DS, ed. UpToDate. Updated December 11, 2019. Accessed March 28, 2021. https://www.uptodate.com/contents/laboratory-assessment-of-thyroid-function
Ross D. Treatment of primary hypothyroidism in adults. In: Cooper DS, ed. UpToDate. Updated September 6, 2019. Accessed March 28, 2021. https://www.uptodate.com/contents/treatment-of-primary-hypothyroidism-in-adults
Columbia Surgery. At-home thyroid testing kits: What we know…and what we don’t: An interview with Dr. Hyesoo Lowe. Columbia Surgery website. Date unknown. Accessed March 28, 2021. https://columbiasurgery.org/news/home-thyroid-testing-kits-what-we-knowand-what-we-dont
U.S. Preventive Services Task Force. Thyroid dysfunction: Screening. Published May 24, 2015. Accessed March 28, 2021. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/thyroid-dysfunction-screening
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