Large goitre in a patient suffering from Graves's disease. In Graves's disease the thyroid gland becomes enlarged (goitre) causing excess production of thyroid hormones (hyperthyroidism). Symptoms include protusion of the eyes (exophthalmos), a rapid heartbeat, sweating, tremor, anxiety, increased appetite, weight loss and intolerance of heat. Treatment is by surgical removal of part of the thyroid gland, admini- stration of radioactive iodine to destroy part of the gland or by the use of drugs that interfere with the production of thyroid hormones. The causes of the disease are not fully understood, but it is thought to be an auto-immune disease.