Thyroid disease: pathophysiology and diagnosis

The thyroid is a butterfly-shaped gland that is located in the front of the neck just above the trachea; it weighs approximately 15 g to 20 g in the adult human. The thyroid produces and releases into the circulation at least two potent hormones, thyroxine (T-4) and triiodothyronine (T-3), that influence basal metabolic processes or enhance oxygen consumption in nearly all body tissues. Thyroid hormones also influence linear growth; brain function, including intelligence and memory; neural development; dentition; and bone development.