Your Thyroid Gland

Your thyroid gland is located at the base of your neck, just below your Adam’s apple. It is shaped like a butterfly. One wing, or lobe, of your thyroid gland lies on each side of your windpipe.

What does the thyroid do?

The purpose of your thyroid gland is to produce, store, and release thyroid hormones into your bloodstream. These hormones, called T3 and T4, affect almost every cell in your body and help control your body’s metabolism. Thyroid cells take up circulating iodine from the blood to create T3 and T4, which are then released into the bloodstream and carried to organs in the body, including the liver, kidneys, muscles, heart, and brain.

If you have too little thyroid hormone in your blood, your body metabolism slows down. This condition is called hypothyroidism. If you have too much thyroid hormone in your blood, your body metabolism speeds up. This condition is called hyperthyroidism.

How does the thyroid work?

The amount of thyroid hormone produced by your thyroid gland is controlled by a gland in your brain called the pituitary gland. Another part of your brain, the hypothalamus, helps the pituitary do its job. The hypothalamus sends information to the pituitary gland, which, in turn, controls the thyroid gland. The thyroid gland, pituitary gland, and hypothalamus all work together to control the amount of thyroid hormone in your body.

These organs work similarly to the way a thermostat controls the temperature in a room. Just as the thermometer in a thermostat senses the temperature of a room, your pituitary gland senses the amount of thyroid hormone in your bloodstream. If your thyroid hormone level is low, the pituitary gland “turns on the heat” by releasing thyroid-stimulating hormone (TSH). TSH sends a signal to your thyroid gland to make more thyroid hormone. The thyroid hormone is then released directly into your bloodstream. When your thyroid hormone levels have been restored to a normal level, your pituitary gland senses this and “turns off the heat,” slowing its production of TSH back to normal.