Hyperthyroidism (leading to increased metabolism)

The whole thyroid gland will normally be slightly swollen. Most people who have this type of hyperthyroidism have different types of eye problems.

These can range from irritated eyes and feelings of dryness to a distinct type of protruding eyes and difficulty closing the eyelids sometimes with additional double vision. The eye problems are more commonly seen in smokers.

Toxic nodular goitre

This is mostly seen among elderly people. The thyroid gland is often non-uniform in shape and rough. In some cases, an increased metabolic rate is caused by a tumour, usually benign, in the thyroid gland. This illness is not generally associated with eye problems.

Subacute thyroiditis

This condition, also known as De Quervain's thyroiditis, is caused by an inflammation of the thyroid gland which is probably due to a viral infection. The inflammation causes an increase in the release of hormones that have been stored in the thyroid gland. This causes temporary symptoms of hyperthyroidism along with some tenderness and swelling of the thyroid.

After the initial illness there may be a period in which the thyroid becomes underactive, but most people recover normal activity within six months.

How do people get hyperthyroidism or thyrotoxicosis?

The causes of hyperthyroidism are not completely known. However, it is assumed that hereditary and environmental factors influence the disease.

In addition to infections it seems likely that environmental factors such as smoking, stress, some types of medication (eg amiodarone - a medicine used to control heart rhythm problems which can also cause hypothyroidism) and both low and high intakes of iodine may cause hyperthyroidism.

What are the symptoms?

- Nervousness, restlessness.
- Trembling hands.
- Rapid heartbeat.
- Feelings of excessive warmth and intolerance of heat.
- Hot, sweaty skin.
- Weight loss despite increased appetite.
- Severe general tiredness.
- Muscle pains and muscle tiredness.
- Frequent loose stools.
- Disturbances of menstruation.

What can people do themselves?

- Make sure they eat a healthy and varied diet, preferably one that includes fish.
- Stop smoking.
- Avoid complementary medicines or dietary supplements with a high iodine content.