The thyroid gland controls important metabolic processes, such as growth and energy expenditure. Hyperthyroidism means the thyroid gland is overactive. An immune system abnormality called Graves' disease is the most common cause of hyperthyroidism.
This condition tends to affect women more than men. Around two in every 100 women will experience some degree of hyperthyroidism. The most common cause is Graves' disease, which is due to an immune system abnormality. Other causes of an overactive thyroid include local inflammation (thyroiditis), nodules or lumps. There is no cure for hyperthyroidism, but it can be successfully managed with treatments such as anti-thyroid medication.