What is Graves disease?
Graves disease is the most common cause of overactive thyroid (hyperthyroidism). It is an autoimmune disorder, an attack on the thyroid gland by a person's own immune system. The thyroid gland is a butterfly-shaped organ that lies flat against the windpipe in the throat. It produces the hormones thyroxine (T4) and triiodothyronine (T3) and plays an important role in controlling the body's metabolism.
Thyroid hormone production is normally regulated in a feedback mechanism that includes the pituitary gland, a pea-sized organ at the base of the brain. The pituitary produces thyroid-stimulating hormone (TSH), which in turn stimulates the production of T4 and T3. With Graves disease, an autoantibody called thyroid stimulating immunoglobulin (TSI) is produced. TSI acts like TSH and causes the thyroid gland to produce excess thyroid hormone. Over time, this can cause the thyroid gland to enlarge.
According to the National Institutes of Health, Graves disease affects almost 10 million people, and it is 5 to 10 times more common in women than men. Graves disease usually occurs in middle age, but it may also occur in children or the elderly. People with other autoimmune diseases and people with family members who have Graves disease are at an increased risk of developing the disease.