Hyperthyroidism is a condition caused by an overactive thyroid gland which produces an excess of thyroid hormones. The symptoms of hyperthyroidism or thyrotoxicosis are many and varied – an enlarged thyroid gland (goitre) and weight loss being some of them – and treatment may include medication, radioactive iodine therapy or surgery.
Hyperthyroidism is the opposite of hypothyroidism or an underactive thyroid.
