Thyroid disorders explained

Hyperthyroidism
Hyperthyroidism means that the thyroid gland is producing and releasing too much hormone. It is most common within the 30-60 age group, and around 90 per cent of cases occur in women.

The leading cause of hyperthyroidism is called Graves' disease. As with Hashimoto's thyroiditis, it is an autoimmune disorder characterised by antibodies that attack the thyroid. The two diseases differ, however, because in the case of Graves' disease, the antibodies cause excess growth to cause general enlargement of the thyroid gland, which then overproduces thyroid hormone. The antibodies may also attack eye muscle tissue and the skin on the front of the lower leg. Graves' disease was named for Robert Graves, an Irish physician who first discussed this form of hyperthyroidism, but it also goes by the name 'diffuse toxic goitre'.

Hyperthyroidism can also be caused by nodules that are overproducing thyroid hormone, a condition known as 'toxic multinodular goitre'. It can also develop during or after pregnancy, or after hypothyroid treatment with an excess of thyroxine.

Symptoms of hyperthyroidism
When too much thyroid hormone is released, the body's metabolic rate increases and the body speeds up. Signs and symptoms of hyperthyroidism include: