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The thyroid gland

Men and woman discussing thyroid cancer

This page tells you about the thyroid gland. You can find the following information

 

A quick guide to what's on this page

The thyroid gland

The thyroid is a gland that makes and releases hormones.  It is at the base of your neck, at the front, just behind the small hollow where your collar bones meet.

The thyroid gland makes hormones that help to control the speed of body processes – your metabolic rate.  If your thyroid gland doesn't make enough of these hormones, you will put on weight and feel very tired and lacking in energy. If your thyroid gland makes too much, you will lose weight and have an increase in your appetite. You may also find it difficult to relax.

The thyroid also makes a hormone that helps to control the amount of calcium circulating in your blood. Calcium is important for your nervous system. Too much calcium can make you feel sick and drowsy. Too little can cause pins and needles, or jerking or twitching muscles.
 

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Where the thyroid gland is

The thyroid is a gland that makes and releases hormones. It is found at the base of your neck, at the front, just behind the small hollow where your collar bones meet.

thyroid_gland

The thyroid gland is in 2 halves, connected by a thinner bridge of thyroid tissue. The bridge is called the isthmus. The two halves are called the lobes of the thyroid. Usually a cancer is found in only one lobe. But with the type of thyroid cancer called medullary thyroid cancer, it can sometimes occur in both lobes.

 

What the thyroid gland does

The thyroid gland makes the following hormones

  • T3, also called tri iodothyronine
  • T4, also called thyroxine
  • Calcitonin

T3 and T4

T3 and T4 help to control the speed of body processes – your metabolic rate. If your thyroid gland doesn't make enough of these hormones, you will put on weight and feel very tired and lacking in energy.

If your thyroid gland makes too much of the T3 and T4 hormones, you will lose weight and have an increase in your appetite. With an overactive thyroid, you may also feel anxious and find it difficult to relax.

Calcitonin

The thyroid gland cells also make a hormone called calcitonin. Calcitonin works in partnership with another hormone called parathyroid hormone. Parathyroid hormone is made by glands called the parathyroid glands, which are behind the thyroid gland and are attached to it. If you have your thyroid gland removed, the parathyroid glands will be left behind. But they can be affected by the operation and may take a while to get back to normal.

Calcitonin and parathyroid hormone control the amount of calcium circulating in your blood. Calcitonin tends to lower calcium levels in the blood by encouraging the bones to store calcium and the kidneys to get rid of it in the urine. Parathyroid hormone encourages the bones to release calcium into the bloodstream and the kidneys to claim it back before it is lost to the body in the urine.

Calcium is important for your nervous system. Too much calcium can make you feel sick and drowsy. Too little can cause problems with the nerves, such as pins and needles and making muscles in your body twitch and jerk.

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Updated: 22 October 2014