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Thyroid Panel Tests

Last updated July 25, 2019

Approved by: Maulik P. Purohit MD, MPH

The Thyroid Panel Tests are a group of blood tests to assess the levels of the thyroid gland hormones T4 and T3.

What are the other Names for this Test? (Equivalent Terms)

  • Thyroid Function Panel Blood Tests 

What is Thyroid Panel Tests? (Background Information)

  • The thyroid gland is situated in the front of the throat, just below the cartilage of the Adam’s apple. It produces 3 main hormones that affect nearly every cell in the body
  • The 2 thyroid gland hormones namely, thyroxine (T4) and triiodothyronine (T3), increase body metabolism. They increase consumption of energy and oxygen, and also stimulate growth and development
  • The third hormone produced by the thyroid gland is calcitonin, made by C cells. It plays a role in decreasing calcium levels in blood, by stimulating calcium excretion by the kidneys, and through calcium uptake by the bones
  • The pituitary gland stimulates the thyroid gland, through production of thyroid-stimulating hormone (TSH). TSH production is in turn stimulated by thyrotropin-releasing hormone (TRH), from the hypothalamus of the brain
  • The system operates via a negative feedback loop; TSH stimulates thyroid gland hormone production, whose increase then inhibits TRH production by the brain. This results in decreased stimulation of TSH production, leading to decreased thyroid gland hormones
  • The thyroid gland uses iodine to make Tand T3. Without iodine, the production of these hormones is stopped or reduced. This can lead to the formation of goiter (swelling) in the neck, as levels of fluid and hormone precursors accumulate
  • Another medical condition of the thyroid gland is that it gets mistakenly targeted by the immune system. This leads to tissue destruction and impaired thyroid function
  • The Thyroid Panel Tests are a group of blood tests to assess the levels of the thyroid gland hormones T4 and T3. Additionally, it also assesses the levels of TSH. This helps in diagnosing disorders of thyroid hormone production

What are the Clinical Indications for performing the Thyroid Panel Tests?

Following are the clinical indications for performing Thyroid Panel Tests:

  • Rapid weight change
  • Goiter
  • Protruding eyes (exophthalmos)
  • Anxiety
  • Tremors
  • Hair loss
  • Menstrual irregularity
  • Rapid heart rate
  • Fatigue 

How is the Specimen Collected for Thyroid Panel Tests?

Following is the specimen collection process for Thyroid Panel Tests:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the Thyroid Panel Tests Result?

The significance of Thyroid Panel Tests is explained:

  • High levels of thyroid-stimulating hormone (TSH) may indicate hypothyroidism, if T3 and T4 levels are also not elevated
  • Low levels of TSH may indicate hyperthyroidism, if T3 and T4 levels are high or normal
  • Low levels of TSH, coupled with low or normal T3 and T4 levels, may indicate secondary hypothyroidism 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. 

Additional and Relevant Useful Information:

  • The thyroid-stimulating hormone (TSH) test is often performed, before other tests in the panel are performed
  • Certain factors interfere with the results of the Thyroid Panel Tests. These include altitude, pregnancy, age, and nutrition status 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 18, 2014
Last updated: July 25, 2019