The thyroid gland

The thyroid is a small gland in the front of your neck just below your voicebox (larynx). It is made up of two parts called lobes.

The thyroid
The thyroid

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The thyroid gland is part of your endocrine system. This system makes hormones that help to control and influence the way your body functions. Your thyroid gland produces two main hormones:

  • thyroxine (T4)
  • triiodothyronine (T3).

These keep your body functioning at the correct speed. If your thyroid gland doesn’t produce enough hormones, your body’s cells will work slower than normal. You’ll feel tired and lethargic and put on weight easily. This is called hypothyroidism.

If your thyroid gland produces too many hormones, your body’s cells will work faster than normal. This is called hyperthyroidism or thyrotoxicosis. You’ll lose weight, feel hungrier than normal, and feel shaky and anxious. Your heartbeat may be faster than normal or irregular.

A part of your brain called the hypothalamus senses if the levels of T3 and T4 in your blood are too low. If they are it sends thyroid-releasing hormones (TRH) into your blood. The rising level of TRH makes another gland in the brain, called the pituitary gland, release thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid gland to produce more T3 and T4.

Thyroid hormones
Thyroid hormones

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The thyroid gland needs a regular supply of iodine, which is found in fish, seafood and dairy products, to produce thyroid hormones. We get iodine from our diet.

Back to Understanding thyroid cancer

What is cancer? (short)

Cancer is a disease of our cells. Sometimes cells go wrong and become abnormal. They keep dividing to make more abnormal cells which form a lump or tumour.

Cancer and cell types

Cancers are grouped into types. Types of cancer often behave and respond to treatments in different ways.

How is it treated?

There are five main types of cancer treatment. You may receive one, or a combination of treatments, depending on your cancer type.