Thyroid 544


What is T3?



T3, or Triiodothyronine, is one of the two main hormones produced by the thyroid gland. Its release is regulated by a hormone called TSH, or thyroid stimulating hormone. T3 is formed through the conversion of the other hormone produced by the thyroid and regulated by TSH, known as T4.

T3 helps the body regulate metabolism, body temperature, and heart rate, among other functions. T3 is also known to assist in brain development, and changes in T3 levels are not uncommon findings in cases of fatigue.

Normal T3 levels suggest a healthy thyroid and a normal balance in the body's systems that regulate and control the release of thyroid hormones.

Measuring T3, which plays a crucial role in several central systems in the body, is particularly interesting and relevant when evaluating thyroid function. Since the release of T3 is controlled by the hypothalamus and pituitary gland in the brain, measuring T3 can also help understand whether these structures are functioning as they should. Thirdly, T3 measurements are relevant when evaluating and monitoring the effects of thyroid hormone treatment.



High levels of T3



High T3 levels, also known as hyperthyroidism, mean that you have an overactive thyroid gland producing an excess of triiodothyronine hormone. The most common causes behind this are conditions in the gland, such as inflammation (thyroiditis), and an autoimmune disorder resulting in an overproduction of thyroid hormones (Grave’s disease). Excessive intake of thyroid hormones through replacement therapy as well as excessive intake of iodine may also result in hyperthyroidism.



Low levels of T3



Low T3 levels, also known as hypothyroidism, mean that your thyroid gland is not producing enough triiodothyronine hormone. The most common causes behind this are conditions in the thyroid, such as inflammation (thyroiditis), and treatments that harm the thyroid, such as surgery and radiation therapy. Iodine deficiency, impaired pituitary function, and certain medications like lithium can also cause hypothyroidism.