Which hormone regulates metabolism and is produced by the thyroid gland?

Thyroxine (T4) is the main hormone produced by the thyroid gland and plays a crucial role in regulating metabolism. This hormone influences the metabolic rate of cells throughout the body, impacting how quickly or slowly they perform their functions, including how the body uses energy, synthesizes proteins, and regulates sensitivity to other hormones.

T4 is synthesized from iodine and the amino acid tyrosine in the thyroid gland. Once released into the bloodstream, it can be converted into triiodothyronine (T3), which is the more active form of the hormone, but T4 itself has significant metabolic effects. The actions of thyroxine lead to an increase in overall metabolism, which includes raising the basal metabolic rate, promoting growth and development, and influencing the metabolism of carbohydrates, fats, and proteins.

The other hormones listed are produced by different glands and serve different functions; insulin is produced by the pancreas and regulates blood glucose levels, cortisol is produced by the adrenal glands and helps manage stress and metabolism, while adrenaline (epinephrine) is also produced by the adrenal glands and primarily prepares the body for a 'fight or flight' response. Thus, the role of thyroxine in metabolism distinctly categorizes it as the correct