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Thyroxine (T4)

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Thyroxine (T4) is the most common form of thyroid hormone that is released by the thyroid gland. Once it reaches the tissues, it is converted to another form of thyroid hormone called triiodothyronine (T3), which is more active in regulating the body's chemical reactions.

In tests of thyroid function, a low T4 level may indicate the presence of low thyroid levels (hypothyroidism). Certain forms of liver or kidney disease may also cause a low T4 level, even though a thyroid problem may not be present.

Current as of: April 30, 2024

Author: Ignite Healthwise, LLC Staff

Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

Current as of: April 30, 2024

Author: Ignite Healthwise, LLC Staff

Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.