Hyperthyroidism is also known as thyrotoxicosis or an overactive thyroid. It occurs when the thyroid gland release too much thyroxine. The thyroid gland is located in the lower part of the neck. The gland wraps around the windpipe and has a shape that is similar to a butterfly formed by two wings and attached by a middle part. This abnormally high level of thyroid hormone typically speeds up the body's metabolism. Metabolism is the chemical and physical processes that create the substances and generate the energy needed for cell function, growth, and division.

Approximately 1 in 50 women and 1 in 1000 men develop hyperthyroidism each year in the UK.

Causes

Many things can cause hyperthyroidism. One of the most common causes of hyperthyroidism is Grave's disease, an autoimmune disorder. Graves' disease is an autoimmune disease. The immune system normally makes antibodies to attack bacteria, viruses, and other 'bugs'. In autoimmune diseases, the immune system makes antibodies against tissues of the body.

Hyperthyroidism or thyrotoxicosis occurs when the thyroid releases too many of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:

* Graves' disease

* Non-cancerous growths of the thyroid gland or pituitary gland

* Tumors of the testes or ovaries

* Inflammation (irritation and swelling) of the thyroid due to viral infections or other causes

* Ingestion of excessive amounts of thyroid hormone

* Ingestion of excessive iodine

Symptoms

The symptoms and signs of Graves' hyperthyroidism are due to the effects of excess amounts of thyroid hormone on body function and metabolism. Common symptoms include weight loss, nervousness, irritability, intolerance to hot weather, excessive sweating, shakiness, and muscle weakness. Other signs include a rapid pulse, loss of body fat and muscle bulk, thyroid enlargement (goitre), fine tremors of the fingers and hot, moist, velvety skin.

Treatment

Treatment will depend on the specific disease and individual circumstances such as age, severity of disease, and other conditions affecting a patient's health.

Surgery is the preferred treatment for people with a large goiter who chronically relapse after drug therapy and for people who refuse or who are not candidates for the radioactive iodine therapy.

Beta blockers. These drugs are commonly used to treat high blood pressure. They won't reduce your thyroid levels, but they can reduce a rapid heart rate and help prevent palpitations. For that reason, your doctor may prescribe them until your thyroid levels are closer to normal.

Prevention

There are no known prevention methods for hyperthyroidism, since its causes are either inherited or not completely understood. The best prevention tactic is knowledge of family history and close attention to symptoms and signs of the disease. Careful attention to prescribed therapy can prevent complications of the disease.