Diseases of the thyroid gland are very common. Around one in 20 people will experience some form of thyroid dysfunction in their lifetime. The thyroid gland controls many vital metabolic processes, such as growth and energy expenditure. The most common thyroid problems are:

  • An overactive gland, called hyperthyroidism
  • An underactive gland, called hypothyroidism
  • Thyroid enlargement due to overactivity or from under-activity. An enlarged thyroid gland is often called a goitre


Hyperthyroidism means the thyroid gland is overactive. The most common cause of hyperthyroidism in Australia is Graves disease, caused by a defect in immunoregulation in genetically predisposed individuals, leading to production of thyroid-stimulating antibodies.

The symptoms of hyperthyroidism include:

  • Accelerated heart rate or palpitations
  • Muscle weakness and trembling
  • Unexplained weight loss
  • Sensitivity to heat
  • Diarrhoea
  • Sleeping difficulties
  • Sweating
  • Irritability
  • Nervousness, agitation and anxiety
  • Changes in menstruation, including scantier flow and increased cycle length.


Hypothyroidism means the thyroid gland is underactive and fails to make enough hormones.

Hypothyroidism is the most common thyroid disorder, and it is thought to affect around six to ten per cent of women. The prevalence rises with age - up to a quarter of women over the age of 65 years may be affected. Men are also affected, but less frequently.

The symptoms of hypothyroidism can be mild, moderate or severe. In its severest form (myxoedema coma), hypothyroidism is potentially fatal and requires urgent medical treatment.
Symptoms of hypothyroidism can include:

  • Fatigue and low energy levels
  • Depression
  • Slow heart rate
  • Unexplained weight gain
  • Intolerance to cold temperatures
  • Fatigued and aching muscles
  • Dry, coarse skin
  • Puffy face
  • Hair loss
  • Constipation
  • Problems with concentration


A goitre is an enlargement of the thyroid gland. The symptoms of a goitre include:

  • Enlargement of the throat, ranging from a small lump to a huge mass
  • Swallowing problems, if the goitre is large enough to press on the oesophagus
  • Breathing problems, if the goitre is large enough to press on the windpipe (trachea)

Goitre can be caused by a range of factors, including:

  • Insufficient iodine in the diet
  • High consumption of certain foods that neutralise iodine, such as cabbage, broccoli and cauliflower. Other foods, like soy, may also induce goitres
  • Thyroid cancer
  • Nodules growing on the thyroid gland
  • Hyperthyroidism (overactive thyroid gland)
  • Hypothyroidism (underactive thyroid gland)