tiroxine

Thyroxine, also known as T4, is a thyroid hormone produced by the thyroid gland. It plays a crucial role in regulating metabolism in most of the body's cells. Thyroxine is synthesized from tyrosine and iodine. The thyroid gland produces both thyroxine and triiodothyronine (T3), with thyroxine being the more abundant form secreted into the bloodstream. However, thyroxine is largely considered a prohormone, as it is converted into the more active form, T3, in various tissues throughout the body.

The production and release of thyroxine are controlled by the pituitary gland and the hypothalamus. The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). TSH then acts on the thyroid gland, prompting it to produce and release thyroxine. This intricate feedback loop helps maintain appropriate levels of thyroid hormones in the body.

Thyroxine influences a wide range of physiological processes, including growth and development, particularly in children. It is essential for the normal development of the brain and nervous system. In adults, thyroxine helps regulate heart rate, body temperature, and the breakdown of carbohydrates, fats, and proteins. Disruptions in thyroxine levels can lead to various health conditions, such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid), which have significant impacts on overall health and well-being.