The thyroid is a butterfly-shaped gland located in the front of the neck. It produces hormones that play a key role in regulating blood pressure, body temperature, heart rate, metabolism and the reaction of the body to other hormones.
The two main hormones produced by the thyroid are triiodothyronine, or T3, and thyroxine (T4). The gland also produces calcitonin, which helps bone cells process calcium and add it to the bones.
Problems with the thyroid include a variety of disorders that can result in the gland producing too little thyroid hormone (hypothyroidism) or too much (hyperthyroidism).