The thyroid gland is a butterfly-shaped gland that is located in the front of the neck. It controls the body’s metabolism (turning food into energy) by producing and releasing thyroid hormone. Thyroid hormone affects heart rate, energy level and mental status, and can also affect the growth and development of children. The thyroid produces mostly thyroxine (T4) but also some triodothyronine (T3), although the tissues generally convert T4 to T3 (by removing one iodide) when they need to. The amount of thyroid hormone released by the thyroid gland is controlled by the pituitary gland and when the thyroid hormone levels are low, the pituitary gland releases more thyroid stimulating hormone (TSH) to tell the thyroid to produce more thyroid hormone.
People with thyroid disease either make too much or too little T4 and T3; too much causes the body to use energy too fast (hyperactive) and too little thyroid hormone causes the body to use energy too slow (hypoactive). Thyroid diseases occur similarly in adults and children, although symptoms and treatment may be somewhat different. In children, some are born with an absent or a dysfunctional thyroid gland (congenital hypothyroidism). Symptoms