How does the thyroid gland work?
The thyroid gland produces thyroid hormone from iodine absorbed from food, which it concentrates and combines with other substances to produce the active forms of thyroid hormone called triiodothyronine (T3) and thyroxine (T4). These compounds are transported around the body in the blood serum bound to proteins as thyroglobulins. Thyroid hormones have a relatively short life and the body requires a regular supply of iodine in the diet to maintain production of the hormone. In some parts of the world the diet of the population is deficient in iodine with dietary levels of iodine being well below the recommended level. Secretion of thyroid hormone is regulated by the pituitary gland. This is a small oval gland situated at the base of the brain and which produces hormones that regulate the action of other hormone-secreting glands in the body. Its function is to orchestrate all metabolic processes. One of these hormones is thyroid-stimulating hormone (TSH or thryotropin), which stimulates
