An autoimmune disorder that causes the thyroid gland to produce too much thyroid hormone (thyroxine). Over production of thyroxine is called hyperthyroidism and Graves' disease is the most common cause of hyperthyroidism. Graves' disease occurs when the body produces antibodies that attack the thyroid gland causing it to enlarge (goiter) and overproduce the thyroid hormone. The disorder is more common in women. The majority of the symptoms experienced are the result of the hyperthyroidism. Graves' disease also causes swelling of the eye muscles and the characteristic protruding of the eyes.