Introducing the Comprehensive Thyroid Panel Test Kit with Vitamin D

Published on February 4, 2025

Hormone balance along with vitamin D optimization are key to optimal health. Testing of thyroid hormones and toxic and essential elements helps get to the root of certain symptoms related to issues involving the thyroid, exposure to toxins, and specific deficiencies.

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Diseases and disfunction of the thyroid are often under-diagnosed. In fact, according to the American Thyroid Association, approximately 12% of the US population will develop thyroid disease at some point during their life, and up to 60% of those individuals will unaware of it and what is causing their related symptoms.

GrassrootsHealth has been offering testing of thyroid stimulating hormone (TSH) for several years as part of the D*action project.  While TSH is a good marker for initially assessing thyroid function, measuring it alone does not offer enough insight as to complete thyroid health or existing imbalances, and additional thyroid markers should be considered to make a proper diagnosis in the case of thyroid disfunction.

Several studies have also found a direct effect of vitamin D supplementation on thyroid function, as well as significant associations between vitamin D levels and the levels of thyroid hormones and thyroid antibodies.  For this reason, GrassrootsHealth has decided to introduce the Comprehensive Thyroid Panel with Vitamin D to further expand our research into vitamin D and thyroid health!  Testing of thyroid hormones with toxic and essential elements helps get to the root of certain symptoms related to issues involving the thyroid, exposure to toxins, and specific deficiencies.

Order the Comprehensive Thyroid Panel Here

Note: This is a ZRT Laboratories branded test kit offered through GrassrootsHealth.  Results will not be posted to the myResults section of your daction.grassrootshealth.net participant account (with the exception of vitamin D). The full set of results will be reported to you as a PDF and will be stored securely in the GrassrootsHealth database for research purposes.

What Symptoms Are Associated with Thyroid Problems?

o Weight gain or inability to lose weight even with exercise and diet
o Feeling cold all the time when others don’t
o Low energy and stamina (unrelieved by sleep)
o Irregular bowel habits – constipation/loose stools
o Dry, thinning, or itchy skin
o Hair loss
o Insomnia
o Water retention
o Menstrual irregularities
o Low sex drive
o Infertility
o Memory lapses or slow/fuzzy thinking
o Dry/brittle hair and nails
o Depression
o Osteoporosis
o Weight loss
o Muscle and joint aches and pains
o High blood pressure
o Increased cholesterol levels
o Heat or cold intolerance

Who Should Test?

The Comprehensive Thyroid Panel is recommended for:

o Individuals over the age of 50
o Anyone with a family history of thyroid disorders
o People experiencing symptoms of thyroid dysfunction
o People, including children, who have Down’s Syndrome
o People with other autoimmune disorders, especially those with history of autoimmune thyroiditis
o Women trying to get pregnant or who are pregnant
o Individuals requiring routine thyroid screening plus an assessment of iodine status and total thyroxine production by the thyroid gland
o People experiencing symptoms of thyroid dysfunction but who have been told their thyroid was OK; this may be a result of nutritional deficiencies or excessive exposure to environmental pollutants that block thyroid synthesis and function
o Anyone with known thyroid problems, whose thyroid medication has been difficult to stabilize, or dosages have fluctuated frequently, or those looking for the cause of their thyroid dysfunction

About the Panel

This full panel provides a detailed assessment of thyroid health, including screening for

o hypothyroidism
o hyperthyroidism
o autoimmune thyroid disease

Subclinical hypothyroidism, defined as elevated TSH associated with normal T3 and T4 levels, is found among approximately 4-10% of the general population and 20% of women over 60 years of age. Less common thyroid conditions that are often missed or overlooked include subclinical hyperthyroidism (low TSH with normal T3 and T4) and Hashimoto’s Disease (identified by high TPO antibodies).  Results can also help monitor the effectiveness of thyroid replacement therapies. Adding important minerals affecting thyroid function and thyroid hormone production gives additional insights into how to support thyroid function and health.

What does the Comprehensive Thyroid Panel Include?

This Comprehensive Thyroid Profile includes the following:

Dried Blood Spot test for TSH, Free T3 (FT3), Free T4 (FT4), TPO Antibodies (TPOab), Thyroglobulin (Tgbn), Total T4 (T4), Vitamin D

Two-Point (Morning and Night) Dried Urine test for Iodine, Bromine, Selenium, Lithium, Arsenic, Cadmium, Mercury and Creatinine

Order the Comprehensive Thyroid Panel Here

Thyroid Panel Markers Included in the Dried Blood Spot Test (with Vitamin D)

TSH (Thyroid Stimulating Hormone)
Produced by the pituitary, TSH acts on the thyroid gland to stimulate production of the thyroid hormones T4 and T3. Higher than normal TSH can indicate a disorder of the thyroid gland, while low TSH can indicate over-production of, or excessive supplementation with, T4 and/or T3, which acts in a negative feedback loop on the pituitary to reduce TSH production. Low TSH can also be caused by problems in the pituitary gland itself, which result in insufficient TSH being produced to stimulate the thyroid (secondary hypothyroidism).

Free T4 (Thyroxine)
T4 (thyroxine) is the predominant hormone produced by the thyroid gland. It is an inactive hormone and is converted to its active form, T3 within cells. Free T4 is the non-bound fraction of the total T4 circulating in the blood. Free T4 is available to the tissues and represents 0.04% of the total T4 levels. High TSH combined with low free T4 levels indicates hypothyroidism while low TSH and high free T4 levels indicates hyperthyroidism.

Free T3 (Triiodothyronine)
The active thyroid hormone that regulates the metabolic activity of cells. Free T3 is the non-protein-bound fraction circulating in the blood, representing about 0.4% of the total circulating T3, which is available to tissues. Elevated T3 levels are seen in hyperthyroid patients, but levels can be normal in hypothyroid patients because it does not represent the intracellular conversion of T4 to T3, which comprises about 60% of all T3 formed in tissues.

TPOab (Thyroid Peroxidase Antibodies)
Thyroid peroxidase is an enzyme used by the thyroid gland in the manufacture of thyroid hormones by liberating iodine for attachment to tyrosine residues on thyroglobulin. In patients with autoimmune thyroiditis (predominantly Hashimoto’s disease), the body produces antibodies that attack the thyroid gland, and levels of these antibodies in blood can diagnose this condition and indicate the extent of the disease.

Thyroglobulin
A protein which is rich in tyrosine and synthesized only in the thyroid gland. When bound to iodine, tyrosine residues in thyroglobulin become the source material for the synthesis of the thyroid hormones T3 and T4. When iodine levels are low, high levels of thyroglobulin can be found in the blood as iodine-poor thyroglobulin builds up and leaks from the thyroid into the bloodstream. Levels of thyroglobulin are an indicator of a person’s average iodine exposure over a period of weeks4: the greater the iodine exposure, the lower the thyroglobulin level. An elevated thyroglobulin, in the absence of more serious thyroid diseases such as thyroid cancer, which results in very high blood thyroglobulin levels, indicates low iodine status.

Total T4 (Thyroxine)
Total T4 includes both free T4 and protein-bound T4, and therefore represents the thyroid gland’s capacity to synthesize, process, and release T4 into the bloodstream. In contrast, free T4 represents only the circulating hormone that is bioavailable and not tightly complexed with thyroid binding globulin (TBG). Certain conditions, like oral estrogen usage or pregnancy, can cause total levels to change due to liver-induction of TBG. This can result in no change in free T4 or lower bioavailable levels of free T4, even though total T4 increases.

Why is measuring specific elements via dried urine important?

Deficiency of iodine and selenium as well as exposure to toxic elements such as bromine, arsenic, selenium, mercury and cadmium can directly affect thyroid function and lead to disease. Urine dried on filter paper strips is a convenient and practical way to test iodine, bromine, selenium, arsenic, mercury, and cadmium to assess deficient, adequate, and toxic intakes. The lab used for this test (ZRT Laboratory) is a pioneer in commercial testing for elements using this simple, two-point (morning and night) urine collection, into which a filter paper strip is dipped and allowed to dry. Their research has shown the dried urine test to be accurate and comparable to full 24-hour liquid collections, which are cumbersome and inconvenient. To correct results for hydration status, creatinine is also measured, and urinary element test results are expressed in μg/g creatinine.

Why is measuring these specific elements important to thyroid health?

Iodine is an essential component of the thyroid hormones T4 and T3. Iodine is an essential nutrient, commonly found in dairy products, seafood, iodized salt, and grains. Iodine deficiency compromises thyroid hormone production and leads to serious diseases including irreversible cretinism, pregnancy complications, goiter, and decreased cognitive function. Iodine deficiency has also been associated with breast cancer. Since over 90% of dietary iodine is eliminated in urine, adequacy of recent iodine intake can be accurately assessed with dried urine testing.

Bromine is a common component of flame proofing agents, fumigants, medications, food products, and pool/spa sanitizers. High environmental exposure can lead to excess accumulation. If iodine status is low, bromine competes with iodine for tyrosine binding sites within thyroglobulin and thereby impedes thyroid hormone synthesis. Bromine is mostly excreted in urine, so dried urine analysis can indicate excessive bromine exposure.

Selenium is an essential dietary element that is incorporated into selenoproteins in the body, which include glutathione peroxidases, thioredoxin reductases, iodothyronine deiodinases, and the extracellular glycoprotein, selenoprotein P10. These selenoproteins play vital roles in thyroid hormone synthesis, free radical scavenging, DNA synthesis, and cancer prevention. Foods such as brazil nuts, seafood, eggs, and grains are significant selenium sources. The optimal therapeutic range for selenium is narrow: excess selenium intake can result in toxicity, while inadequate selenium affects thyroid function because of impaired synthesis and conversion of T4 into the active T312. Urine is the major route of selenium elimination, therefore dried urinary selenium is an indicator of dietary selenium intake.

Arsenic is an environmental toxin, found in well water as well as some foods such as fish, shellfish, seaweed, rice, and fruit. Arsenic is a heavy metal with multiple toxic effects in the body including carcinogenesis, goiter, diabetes, skin diseases, and damage to the liver, kidney, and the cardiovascular, nervous, and endocrine systems. It also competes with selenium, preventing its incorporation into the selenoproteins. This reduces the levels of selenium-containing antioxidants and also the selenoenzymes that are essential for thyroid hormone production, thereby severely compromising thyroid function. Dried urinary arsenic is a good indicator of recent arsenic exposure, since around 80% of dietary arsenic is excreted into urine within 3 days.

Mercury is a highly toxic heavy metal that can accumulate in body tissues including the brain. Besides occupational exposure, most human exposure to mercury is through dental amalgams, seafoods, and vaccinations. Mercury toxicity can cause nervous system damage, leading to symptoms such as paresthesia, mood changes, and sensory disturbances, while very excessive exposure can also lead to renal toxicity, respiratory failure and death. Mercury and selenium have a very high affinity for each other and form a tight complex; as a result, mercury reduces the biological availability of selenium and may inhibit the formation of selenium-dependent enzymes, affecting thyroid function in the same way as selenium deficiency or arsenic exposure. This is particularly problematic in people with inadequate selenium intake and consequent low selenium levels. Selenium can protect against mercury toxicity by sequestering mercury, reducing its bioavailability.

There are three forms of mercury in the environment: elemental, found in batteries, thermometers, and dental amalgams; inorganic compounds, primarily mercuric chloride, present in skin-lightening creams; and organic compounds, primarily methylmercury, found in sea foods. Elemental mercury is most commonly breathed in as a vapor and absorbed through the lungs, while inorganic and organic compounds are ingested and absorbed through the intestine. The predominant form of mercury in urine is inorganic mercury. Urinary mercury level is an excellent biomarker for whole body exposure to both elemental and inorganic mercury.

Cadmium is rated the 4th most toxic heavy metal after arsenic, lead, and mercury on the priority list of hazardous substances issued by the CDC’s Agency for Toxic Substances and Disease Registry (ATSDR). Occupational exposure arises mainly from smelting and battery manufacturing. Cadmium gets into the atmosphere as a result of this industrial activity, as well as via fossil fuel combustion and waste incineration, and is deposited in the soil where it is taken up by plants and thus eventually enters the human food supply. Tobacco leaves are particularly efficient at accumulating high levels of cadmium from soil, and so smoking is a major source of human cadmium exposure. Smokers have about twice the body burden of cadmium compared to non-smokers. In non-smokers, the primary source of exposure is through the food supply. Once inside the body, cadmium binds to albumin and metallothionein in the circulation and is filtered by the kidneys where it accumulates in the kidney cortex. In the kidneys, the half-life of cadmium is more than 10 years; urinary cadmium correlates with tissue levels in the kidneys and is thus accepted as an accurate measure of long-term total body burden of cadmium. Cadmium can also accumulate in the thyroid gland, resulting in damage to thyroid tissues with chronic exposure. An overall positive association has been observed between urinary cadmium and levels of total T4, total T3, free T3, and thyroglobulin in the National Health and Nutrition Examination Survey (NHANES).

Creatinine is a metabolic by-product that is excreted at a relatively constant rate as long as kidney function is not impaired. It is measured to correct dried urinary element levels for hydration status; the greater the fluid intake, the lower the creatinine level. Iodine, bromine, selenium, arsenic, mercury, and cadmium results are therefore expressed in μg/g creatinine to allow for urine dilution.

Advantages of Dried Urine for Testing Iodine, Bromine, Selenium, Arsenic, Mercury, and Cadmium

• Urine collection and shipment of the dried filter strips are simple and convenient for the patient and practitioner
• Dual collections of urine directly on a filter strip, upon awakening and just before bed, are far more convenient and less subject to the inherent inaccuracies of a 24 h urine collection, yet correlate well with 24 h urine collections
• Iodine, bromine, selenium, arsenic, mercury, cadmium, and creatinine in dried urine are exceptionally stable for weeks at room temperature allowing more flexibility in collection, shipment, testing, and storage
• Elements test results expressed in μg/g creatinine allows normalization of results when problems exist with urine that is very concentrated or dilute

Important Notes Regarding the Test

• For women, urine collection must be done when not menstruating
• If using hormones, refer to the Testing Instructions sheet for specific instructions depending on the type of hormones being used
• Avoid Biotin/Vitamin B7 for 3 days prior to testing
• Refrain from drinking more than 8 oz of water in the hour before each dried urine strip collection to allow urine to concentrate
• Complete the dried blood spot and strip #1 of the dried urine test upon waking in the morning; complete strip #2 of the dried urine test before bed
• See additional, detailed step-by-step instructions on the instruction sheet included

Expectations Regarding Testing and Results

This is a ZRT Laboratory branded test kit being offered through GrassrootsHealth. Samples will be sent directly back to ZRT Laboratory and results will be reported back to the GrassrootsHealth ordering provider. Results will NOT be posted to the myResults section of your daction.grassrootshealth.net participant account (with the exception of vitamin D). Your full set of results will be reported to you as a PDF and will be stored securely in the GrassrootsHealth database for research purposes.

Order the Comprehensive Thyroid Panel Here