Thyroid Test Plus is an extended blood test for those who want to get a broader picture of both the thyroid's hormonal function and possible autoimmune effects. The test analyzes TSH, free T4 and free T3 as well as the antibodies TPO and TRAK. The hormone tests show how the thyroid gland is functioning at the time of the test. The antibodies can provide additional information about why the thyroid values are abnormal, for example whether an autoimmune thyroid disease such as Hashimoto's thyroiditis or Graves' disease may be behind it.
Thyroid Test Plus is particularly suitable for those who have symptoms of hyper- or hypofunction, have previously had abnormal thyroid values, have thyroid disease in the family or want to do a more comprehensive check than with a regular thyroid test. A doctor's report is included and helps you understand how the results should be assessed together.
Why choose Thyroid Test Plus?
A basic thyroid test with TSH, free T4 and free T3 provides information about the thyroid's hormone production and regulation. It can show whether the test pattern indicates hypofunction or hyperfunction. Thyroid Test Plus also contains TPO antibodies and TRAK. These analyses can provide clues as to whether an autoimmune process is behind a possible disorder:
- TPO antibodies can provide support for autoimmune thyroiditis, such as Hashimoto's thyroiditis.
- TRAK is primarily associated with Graves' disease, which is a common autoimmune cause of hyperthyroidism.
The smaller thyroid test therefore primarily answers the question of how the thyroid gland functions. The Plus package provides a broader assessment by also investigating whether an autoimmune cause may be behind altered hormone values.
Who is the extended thyroid test suitable for?
The test may be relevant if you are experiencing symptoms that could be consistent with a thyroid disorder. The symptoms are often non-specific and may also have other causes, but a sample can provide important information in a further medical assessment.
Symptoms that may occur with underfunction
- fatigue and decreased energy
- feeling cold
- weight gain or difficulty losing weight
- dry skin and hair loss
- constipation
- depressed mood or difficulty concentrating
- muscle and joint pain
- irregular menstruation
Symptoms that may occur with overfunction
- palpitations or high pulse
- sweating and sensitivity to heat
- weight loss despite unchanged or increased appetite
- anxiety, irritability or difficulty sleeping
- tremors in the hands
- muscle weakness
- loose stools or diarrhea
- eye problems or a feeling of pressure over the neck
The health check may also be a suitable option if you:
- have previously had abnormal TSH, free T4 or free T3
- have close relatives with Hashimoto's thyroiditis, Graves' disease or another autoimmune thyroid disease
- have another autoimmune disease yourself
- have previously had positive thyroid antibodies
- would like to supplement an assessment of hormone function with autoantibody analyses
Five thyroid markers included
TSH – pituitary control signal to the thyroid gland
TSH, thyroid-stimulating hormone, is produced in the pituitary gland and regulates the thyroid gland's production of T4 and T3. TSH is therefore not a thyroid hormone, but the body's central control signal to the thyroid gland. An elevated TSH may be a sign that the pituitary gland needs to stimulate the thyroid gland more to maintain hormone production. A low TSH may mean that the body is trying to reduce stimulation due to high levels of thyroid hormone. TSH always needs to be assessed together with, above all, free T4.
Free T4 – the thyroid's main hormone
T4, thyroxine, is the hormone that the thyroid gland produces in the largest amount. The analysis measures free T4, which is the part of the hormone that is not bound to transport proteins in the blood and is available to the body's tissues. Free T4 is assessed together with TSH to distinguish between, for example, manifest and subclinical thyroid disorders. A high TSH together with low free T4 may indicate primary hypothyroidism, while a low TSH and high free T4 may indicate hyperthyroidism.
Free T3 – the more biologically active form
T3, triiodothyronine, is the more biologically active form of thyroid hormone. Some is produced in the thyroid gland, but a large part is formed by the conversion of T4 to T3 in the body's tissues. Free T3 is particularly useful in suspecting hyperthyroidism. In some cases, TSH may be low and free T3 elevated even though free T4 is still within the reference range. Free T3, on the other hand, has a more limited role in the investigation of hypothyroidism.TPO antibodies – marker for autoimmune thyroiditis
TPO antibodies are autoantibodies directed against thyroperoxidase, an enzyme that the thyroid gland needs to form T4 and T3. Elevated TPO antibodies can support the immune system's reaction against the thyroid gland. TPO antibodies are common in Hashimoto's thyroiditis, which is an autoimmune and common cause of hypothyroidism. The antibodies can also be found in other autoimmune thyroid conditions and in people who still have normal hormone levels.
A positive result therefore does not automatically mean that the thyroid gland has impaired function. The result needs to be assessed together with TSH, free T4, symptoms and other medical information.
TRAK – antibodies linked to Graves' disease
TRAK are autoantibodies directed against the thyroid's receptors for TSH. In Graves' disease, the antibodies usually stimulate the receptors, which can lead to the thyroid gland producing too much T4 and T3. A positive TRAK result can provide strong support for Graves' disease when hormone tests and symptoms simultaneously suggest hyperthyroidism. TRAK is not a general test for all forms of hypothyroidism or hyperthyroidism, but is primarily used to identify or monitor Graves' disease.
How are thyroid tests interpreted together?
It is the combination of markers that provides the most useful information. Common test patterns may include:
- Elevated TSH and low free T4 may indicate manifest primary hypothyroidism.
- Elevated TSH and normal free T4 may indicate subclinical hypothyroidism.
- Low TSH and elevated free T4 and/or free T3 may indicate hyperthyroidism.
- Positive TPO antibodies may support an autoimmune cause, such as Hashimoto's thyroiditis.
- Positive TRAK together with a test pattern for hyperthyroidism may support Graves' disease.
A single abnormal result is not always sufficient to establish a diagnosis. Temporary illness, pregnancy, medications, dietary supplements and laboratory methods can affect the result. In some situations, repeat testing or further medical evaluation may be needed.
What can't the test show?
The blood test alone cannot diagnose all thyroid diseases and cannot show the shape or structure of the thyroid gland. Nodules, goiters, or other structural changes may need to be examined by a doctor and sometimes an ultrasound.
Normal antibody levels do not rule out all forms of thyroid disease. Similarly, positive antibodies do not automatically mean that hormone production is affected or that treatment is needed.
