Thyroxine

Thyroxine, also known as T4, is a type of hormone that is produced and released by the thyroid gland. It is one of the two primary hormones produced by the thyroid, the other being triiodothyronine (T3). Thyroxine plays a crucial role in heart rate, metabolism, and development.

Production and Function

Thyroxine is produced in the thyroid follicles. Its production is stimulated by thyroid-stimulating hormone (TSH), which is released by the pituitary gland. The production and release of thyroxine are part of the hypothalamic–pituitary–thyroid axis, which is a complex set of interactions between the hypothalamus, pituitary gland, and thyroid gland.

Thyroxine functions by entering cells and interacting with the nucleus, affecting the production of proteins and enzymes. This interaction influences numerous physiological processes, including metabolism, heart rate, and development.

Medical Significance

Abnormal levels of thyroxine can lead to several medical conditions. Hypothyroidism is a condition characterized by low levels of thyroxine, leading to symptoms such as fatigue, weight gain, and depression. On the other hand, hyperthyroidism is a condition characterized by high levels of thyroxine, leading to symptoms such as rapid heart rate, weight loss, and anxiety.

Thyroxine levels can be measured through a blood test, and abnormalities can be treated with medication. Levothyroxine is a synthetic form of thyroxine that is commonly used to treat hypothyroidism.

See Also

• Thyroid
• Hormone
• Hypothyroidism
• Hyperthyroidism

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