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Thyroid gland

2-minute read

The thyroid is a small bow-shaped gland that sits in the front of the neck, just below the Adam’s apple. It produces the hormones:

  • triiodothyronine (T3), a hormone that controls energy levels, temperature, metabolism, heart rate, blood pressure and development of a fetus
  • thyroxine (T4), a hormone that controls how the heart works, metabolism, health of the muscles and bones and brain development. Some thyroxine is changed into triiodothyronine
  • calcitonin, which controls the amount of calcium and phosphate in the blood
Illustration showing the endocrine system.
The endocrine system.

What medical conditions are related to the thyroid gland?

Almost 1 in 6 Australians has a thyroid problem. The chance of having trouble with your thyroid becomes greater as you get older.

Sometimes people have problems with their thyroid being overactive and producing too much thyroxine (hyperthyroidism). It can be caused by an autoimmune disorder causing inflammation of the thyroid gland, Grave’s disease, or nodules on the thyroid. Hyperthyroidism makes the body use energy too quickly. Symptoms of hyperthyroidism include:

  • weight loss
  • fatigue
  • nervousness or feeling anxious
  • racing heart and palpitations
  • increased appetite
  • losing weight
  • shaking
  • difficulty sleeping
  • irregular periods
  • infertility
  • hair loss
  • sensitivity to heat

In contrast, if the thyroid gland doesn’t produce enough hormones (hypothyroidism), the metabolism will reduce. This is the most common thyroid condition in Australia and is more common in men. It is often caused by the autoimmune disorder Hashimoto’s disease, but it can also be caused when the thyroid is damaged during surgery or cancer treatments.

Symptoms of hyperthyroidism include:

  • being more sensitive to the cold
  • fatigue
  • dry skin
  • brittle hair
  • constipation
  • weight gain
  • depression
  • aches and pains
  • heavy or irregular periods
  • looking pale
  • swollen face, hands, ankles or feet
  • sleep problems
  • breathlessness
  • difficulty getting pregnant
  • an enlarged thyroid gland (goitre)

Hypothyroidism is usually permanent and is treated by replacing thyroxine.

Your doctor will be able to diagnose these problems by performing a blood test to check for the levels of thyroxine and other related hormones in your body.

If you have a problem with your thyroid, many different treatments are available. They might involve medication and, in some cases, your doctor may recommend surgery.

More information

Learn more about the endocrine system and the different hormones released by the endocrine glands.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2020

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