What causes hyperthyroidism (overactive thyroid)?
There are several causes of hyperthyroidism, the most common is an autoimmune disease called Graves’ disease or diffuse toxic goitre (see below). Graves’ disease occurs when antibodies , which are usually produced to fight infections stimulate the thyroid gland into producing increased amounts of thyroid hormones. This usually causes the thyroid gland to become enlarged, called a goitre. Scientists are not exactly sure what causes Graves’ disease though it does tend to be an inherited condition, especially among female members. Graves’ disease may also be triggered by stress. In the elderly a condition called toxic nodular goitre may cause hyperthyroidism. Toxic nodular goitre occurs when one or more small benign tumours in the thyroid gland produce excess thyroid hormones. The thyroid gland may also become inflamed for unknown reasons or due to a viral infection, the inflamed gland can cause excess thyroid hormones, stored in the gland, to leak into the bloodstream. This is usually a
