Which hormones does the thyroid gland produce?

The thyroid gland produces three primary hormones:

• Thyroxine (T4): This hormone contains four iodine atoms and is produced and secreted by the thyroid gland in significantly larger quantities than triiodothyronine. It serves primarily as a circulating precursor that is converted into triiodothyronine in various tissues throughout the body.12
• Triiodothyronine (T3): Containing three iodine atoms, this is the biologically active form of thyroid hormone that exerts most of its effects on target tissues. While the thyroid gland produces some T3 directly, the majority is generated through the deiodination of thyroxine in other parts of the body.1
• Calcitonin: This protein hormone is synthesized and secreted by the parafollicular cells (or C cells) of the thyroid gland. Its primary function is to lower blood calcium and phosphorus concentrations when they exceed normal levels, acting in opposition to the parathyroid hormone.3

These hormones are essential for regulating various metabolic processes and maintaining mineral balance within the body.13