To fully understand your thyroid function, you need lab work that tests several biomarkers.
A complete thyroid panel includes:
Thyroid-stimulating hormone (TSH)
Free triiodothyronine (free T3)
Free thyroxine (free T4)
Many doctors only look only at thyroid-stimulating hormone (TSH) to assess thyroid health. The pituitary gland produces TSH in your brain, which then tells the thyroid gland to make and release thyroid hormones into your blood. Unfortunately, testing TSH alone offers only a narrow understanding of thyroid function. It doesn't give a comprehensive picture of how the body uses circulating thyroid hormones.
Measuring free T4, free T3, and reverse T3, in addition to TSH, can help paint a fuller picture about what's happening with your thyroid health and how to make specific improvements. Each test offers different information to tailor a treatment plan for your particular needs.
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Free thyroxine (fT4)
T4 is primarily inactive and serves primarily as a "storage hormone" to transport T3 to other organs in your body. T4 must convert to T3 before it's usable by your body for cellular energy. A T4 test helps determine the level of thyroid hormone in the body. Still, this information on its own is incomplete because it can be affected by the amount of protein in the blood.
Free triiodothyronine (fT3)
T3 is the active form of thyroid hormone, becoming active once converted from T4 in the liver (primarily) and other body tissues. T3 is responsible for regulating cellular metabolism. A T3 test helps determine how much of the thyroid hormone in the body is usable.
Reverse T3 (rT3)
Reverse T3 (rT3) is the metabolically inactive form of T3. Typically, T4 converts to T3, but it can also form rT3. Reverse T3 binds to a cell in the same way that T3 does. However, with reverse T3, nothing happens as it's metabolically inactive. When this occurs, reverse T3 and T3 compete for receptors at the cellular level, and your body can show symptoms of hypothyroidism when not enough active T3 binds to the cells.
Testing for antibodies can help confirm autoimmune processes that may affect the thyroid. Testing TPO antibodies can help diagnose Hashimoto's disease, an autoimmune condition where the immune system mistakenly attacks the thyroid gland. Hashimoto's disease is the leading cause of hypothyroidism in the United States. Testing for thyroglobulin antibodies (Tg antibodies) can also confirm Hashimoto's disease, as well as Graves' disease and postpartum thyroiditis. Tg tests also help detect cancer reoccurrence and may predict long-term outcomes of cancer treatment.
When you receive results from your thyroid lab tests, results measure against normal reference ranges. Reference ranges are based on the average values in a population rather than individualized values, meaning that a reference range does not consider the clinical picture of a specific patient but is simply the average values and standard deviations of adults in an area.
You may still experience symptoms of hypothyroidism even if your results fall into the normal test range. Your optimal range is the range in which you feel your best with the least number of symptoms.
Often, patients whose lab values fit within these normal ranges but who still experience hypothyroid symptoms are dismissed or given a one-size-fits-all treatment approach.
To determine the best treatment option to get you into your optimal range, work with a healthcare provider who considers your symptoms, medical history, lifestyle, and lab results.
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How at-home thyroid testing works
Thyroid blood tests tell if your thyroid gland is functioning correctly by measuring the levels of thyroid hormones in your blood. Typically, these thyroid function tests are done by withdrawing blood from a vein in your arm.
However, dried blood spot collection is an alternative solution for collecting, preserving, and transporting blood samples. This at-home testing method eliminates the need for a venipuncture blood draw in a lab. This method also offers convenience by taking your blood sample from the comfort of your own home without a doctor's lab order.
Dried blood spot collection requires a blood sample using a finger-prick via a small lancet. A few droplets of blood are dropped onto specially manufactured absorbent filter paper, where they dry before shipping to a lab.
Dried blood spot testing has been available for decades. In the early days, technology was not advanced enough to screen small blood sample volumes. However, as mass spectrometry (an analytical technique) expanded into clinical laboratories, the applications of blood spot collection grew, too.
With the Paloma Health at-home thyroid test kit, the best time to take your thyroid blood sample is in the morning. However, you can take your sample at any time. What's most important is that each time you take your labs, you take them at the same time of day for consistency.
Our lab uses a specialized assay, and there is no need to delay your medications or supplements. You may also take the test with or without food, so there is no need to fast!
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Thyroid blood test vs. ultrasound
Ultrasounds can provide high-resolution images of your organs to help your doctor better understand your general health. Your healthcare provider may order a thyroid ultrasound as part of a comprehensive physical exam.
Additionally, your thyroid doctor may order an ultrasound if your thyroid blood test is abnormal or if they feel a growth on your thyroid during an exam. Ultrasounds may also occur if your doctor needs to biopsy your thyroid or surrounding tissues to test for existing conditions.
If your healthcare provider notices abnormal swelling, pain, or infections, they may also order an ultrasound. An ultrasound may help uncover any underlying condition causing these symptoms.
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Reverse T3 is an adaptive mechanism to support the body when you don't have as much thyroid hormone activity at the tissue level. For example, if a patient is experiencing extreme stress, trauma, surgery, or malnutrition. Then, assessing rT3 may be a valuable marker.
Another time it may be helpful to monitor rT3 levels is in euthyroid sick patients (also called nonthyroidal illness syndrome). These patients have a healthy thyroid (euthyroid) and are hospitalized in the intensive care unit because they are critically ill. Typically, these patients suffer from severe illness or have had major surgery, restricting calorie intake. Reverse T3 is often elevated in these patients, while T3 is low and T4 and TSH are normal. Treating euthyroid sick patients does not usually require thyroid medication; instead, it requires treating the underlying cause of severe illness.
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Importance of antibody testing
The thyroid gland produces hormones that regulate your body's energy use, along with other vital functions. When your thyroid hormone production dips, your body processes slow down, affecting essentially every system in your body.
There are several reasons why the thyroid gland may not produce enough thyroid hormone.
Common causes of hypothyroidism include:
Surgical removal of part of all of the thyroid gland
Hashimoto's thyroiditis (autoimmune thyroid disease) is the leading cause of hypothyroidism in the United States. Hashimoto's thyroiditis is an autoimmune condition that damages the thyroid gland when immune cells mistakenly attack healthy tissue instead of protecting it.
The difference between Hashimoto's thyroiditis and hypothyroidism is that hypothyroidism is the state of an underactive thyroid, whereas Hashimoto's is an autoimmune condition that can cause hypothyroidism. Essentially, hypothyroidism is an issue with your thyroid gland, and Hashimoto's is an issue with your immune system. You can have one condition without the other. However, they commonly come hand-in-hand without early detection of TPO antibodies that are present in Hashimoto's.
Thyroid antibodies can be the first evidence of a thyroid problem. However, thyroid antibodies in the blood do not necessarily mean that a person has hypothyroidism. However, it representsa continuous attack against the thyroid, increasing your risk of future thyroid disorders. Early detection of TPO antibodies in the blood means you can slow disease progression.
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What is thyroid genetic testing?
Genetics is one factor that discerns the concentrations of hormones in our body, including thyroid hormones and TSH (thyroid-stimulating hormone). Some studies even suggest that genetics are the basis for 67% of circulating thyroid hormone and TSH concentrations. These stats mean we may have a specific set point (a physiological value around which the normal range fluctuates) for each hormone.
There are thyroid-specific gene SNPs (single nucleotide polymorphisms) on your DNA profile that can give insight into your genetic risks of thyroid disease. These SNPs (pronounced "snips") are standard genetic variations. Each SNP expresses a difference in a single DNA building block, called a nucleotide.
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To better understand your genetic profile or risks, an at-home genetic test like 23 and Me can provide a wealth of information. Of course, while genes may play a role in some thyroid diseases, including thyroid cancer, other factors like age, sex and environment also influence your health outcomes.
Learn how genes influence your thyroid function in this article.
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What to do if labs come back normal
It can feel frustrating to get your lab results back only to learn that everything is "normal" despite not feeling that way. The symptoms of hypothyroidism are often similar to many other conditions, and it's still possible to still experience symptoms of low thyroid with normal labs.
There are many other causes of thyroid-like symptoms like subclinical hypothyroidism, vitamin or mineral deficiencies, chronic stress, or poor thyroid hormone conversion. Recognizing additional signs can help you and your doctor work together to make the correct diagnosis.
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How much thyroid testing costs
While thyroid blood tests are important, the cost of blood work without insurance can be pretty costly. Getting blood work done at a lab can range anywhere from $100 for a simple test to several thousand dollars for several complex tests. This steep cost of testing without insurance keeps many patients from getting the blood testing that they need. Ultimately, this leads to delayed diagnosis, worsening the prognosis and usually increasing the overall cost of treatment.
One way to make blood work testing more affordable is to explore at-home testing options. At-home blood testing allows people to take a more active role in their health and makes blood testing more accessible and affordable to more people. At-home blood tests are less expensive than ordering from a lab when a patient doesn't have insurance or for people who have insurance but are on a high deductible plan.
Out of pocket, the Paloma Health at-home thyroid test kit is $99. In many cases, our test kit is eligible for some amount of coverage by insurance providers. Coverage will depend on your coverage plan. We encourage patients to check with their insurance company to see whether they will cover all or some of the cost of our at-home thyroid test. Medicare and Medicaid are unlikely to cover this type of at-home test.
When discussing coverage, your carrier should understand precisely what the test is and what it is testing. They'll want to know that the test is taken at home via a blood sample and analyzed by our partner laboratories. The test measures:
The Paloma Health at-home thyroid test kit is also FSA- and HSA-eligible.
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