What is the Difference Between Thyroxine and Triiodothyronine?

Thyroxine (T4) and triiodothyronine (T3) are two main hormones produced by the thyroid gland that play crucial roles in regulating various bodily functions, including metabolism, digestive functions, and brain development. The key differences between them are:

1. Form: T4 contains four iodine atoms, while T3 contains three iodine atoms.
2. Activity: T3 is the active form of the thyroid hormone, meaning it impacts cells and tissues, while T4 is largely inactive and must be converted into T3 to become active.
3. Conversion: T4 is converted into T3 in various organs and tissues, such as the liver and kidneys. This process is essential for maintaining a proper balance of thyroid hormones in the body.
4. Secretion: The thyroid gland produces and secretes T4, while T3 is derived from T4 through the process of deiodination.

Thyroid-stimulating hormone (TSH), secreted by the pituitary gland, regulates the production and release of T4 and T3. Hypothyroidism, an underactive thyroid, can result from insufficient production of these hormones, leading to symptoms such as fatigue, weight gain, and depression. On the other hand, hyperthyroidism, an overactive thyroid, can occur when there is an excess of thyroid hormones, causing symptoms like rapid heartbeat, weight loss, and anxiety. It is essential to monitor and maintain healthy thyroid hormone levels to prevent these conditions and ensure overall health.

Comparative Table: Thyroxine vs Triiodothyronine

Thyroxine (T4) and triiodothyronine (T3) are thyroid hormones that play crucial roles in metabolism and digestive functions. They have several differences, which are summarized in the table below:

T3 is generated from the peripheral metabolism of T4 by iodothyronine deiodinases, which remove iodine atoms from iodothyronines. Both hormones are secreted by the thyroid gland, but T3 is also generated from the peripheral metabolism. While T4 is the inactive form of the hormone, T3 is the active counterpart, meaning that body tissues need to convert T4 into T3 for use.