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Hyperthyroidism - What it is

The thyroid is a butterfly-shaped gland situated in the front of the neck. Its main function is to produce two hormones - thyroxine and triiodothyronine - which are crucial to the control of various bodily functions.

Should the thyroid malfunction, it can cause health problems that can affect your quality of life. Women are more susceptible than men to thyroid disorders. Thyroid hormone (TH) imbalances are usually related to autoimmune disorders - when healthy cells and tissues in your body are mistakenly attacked by your own immune system. It is not known why this happens, but there appears to be a genetic link.

Too little, too much?

When an underactive gland doesn't produce enough thyroid hormones to adequately meet the body's needs, the condition is referred to as hypothyroidism. Conversely, in hyperthyroidism; an overactive thyroid gland results in the excessive production of thyroid hormones. Hypothyroidism and hyperthyroidism are the two most common thyroid disorders in women between the age of 20 and 50, who are also five times more likely than men to develop thyroid disorders.


Hyperthyroidism can lead to a number of complications such as:

  • Irregular heartbeat. This can worsen heart problems such as angina.
  • Brittle bones (osteoporosis). Excessive thyroid hormones can affect your body's absorption of calcium into the bones.
  • Eye problems. Grave's disease can cause protrusion of the eyes as well as sensitivity to light and blurring or double vision.
  • Thyrotoxic crisis. The sudden intensification of hyperthyroidism symptoms, leading to fever, rapid pulse and even delirium.

Hyperthyroidism - Symptoms

Signs and symptoms of an overactive thyroid include:

  • Sudden, unexplained weight loss
  • Increased sensitivity to heat
  • Increased heart rate
  • Nervousness, anxiety and irritability
  • Hand tremors
  • Changes in menstrual patterns
  • Diarrhoea
  • Bulging eyes
  • Enlarged thyroid gland (goiter) that can appear as a swelling at the base of the neck
  • Fatigue, muscle weakness
  • Restlessness and insomnia

Hyperthyroidism - How to prevent?

Hyperthyroidism - Causes and Risk Factors

In 70% of the cases, hyperthyroidism results from an autoimmune disorder known as Graves' disease, a condition in which the body's own antibodies attack the thyroid. This causes it to produce too much of the hormone thyroxine, which speeds up the body's metabolism in turn.

Hyperthyroidism - Diagnosis

Hyperthyroidism - Treatments

Hyperthyroidism - Preparing for surgery

Hyperthyroidism - Post-surgery care

Hyperthyroidism - Other Information

The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth