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What Is the Thyroid?

The thyroid is a small gland below the skin and muscles at the front of the neck, at the spot where a bow tie would rest. It makes two types of thyroid hormones: T3 (triiodothyronine) and T4 (thyroxine). It helps the body do many things, such as get energy from food, grow, and go through sexual development.

The pituitary is a pea-sized gland at the bottom of the brain that makes thyroid stimulating hormone (TSH). TSH triggers the thyroid to make more thyroid hormone. The pituitary gland and the thyroid gland send messages back and forth to each other about how much hormone to make to keep the levels normal.