Thyroid Gland Facts



  • The thyroid is a small gland about the size of two joined cherries. It is situated at the front of your neck, just below the larynx.
  • The thyroid secretes (releases) three important hormones – tri-iodothyronine (T3), thyroxine (T4) and calcitonin.
  • The thyroid hormones affect how energetic you are by controlling your metabolic rate.
  • Your metabolic rate is the rate at which your body cells use glucose.
  • T3 and T4 hormones control metabolic rate by circulating into the blood and stimulating cells to convert more glucose.
  • If the thyroid sends out too little T3 and T4, you get cold and tired, your skin gets dry and you put on weight.
  • If the thyroid sends out too much T3 and T4, you become nervous, sweaty and overactive, and you will also lose weight.
  • The amount of T3 and T4 sent out by the thyroid depends on how much thyroid-stimulating hormone is sent to it from the pituitary gland (see the brain).
  • If the levels of T3 and T4 in the blood drop, the pituitary gland sends out extra thyroid stimulating hormone to tell the thyroid to produce more.