Graves' disease is a condition in which the body's immune system attacks the thyroid gland, causing an overproduction of a hormone called thyroxine. This hormonal excess is known as hyperthyroidism. Graves' disease is the most common cause of hyperthyroidism, which causes the body's metabolism to speed up.

The thyroid gland sits just below the Adam’s apple in the neck. It secretes hormones (especially thyroxine) that regulate a person’s metabolism, the physical and chemical processes necessary for the maintenance of life. Thyroid hormones help to:

• Control the rate at which the body uses fats and carbohydrates
  
• Maintain body temperature
  
• Influence heart rate
  
• Regulate the amount of calcium in the blood

Graves' disease can increase a person's metabolism by between 60 to 100 percent. Patients may experience symptoms such as anxiety and irregular heartbeat. The disease rarely is life-threatening if treated properly.

Graves' disease is an autoimmune disorder. In a healthy person, the immune system uses proteins called antibodies and white blood cells to attack harmful substances that enter the body, including viruses, bacteria and other foreign substances. Patients with autoimmune disorders have antibodies that attack normal cells as if they were foreign invaders. In Graves' disease, an antibody called thyrotropin receptor antibody causes the thyroid to make excessive amounts of thyroid hormone.

Hyperthyroidism may cause complications including heart problems, osteoporosis and, according to recent research, glaucoma, a leading cause of blindness.

Some cases of Graves' disease cause the eyes to bulge beyond their normal protective orbit. This occurs when tissues and muscles behind the eyes swell, a condition known as Graves' ophthalmopathy. As the eye pushes out farther, it is more vulnerable to dryness. Inflammation associated with this process causes a buildup of scar tissue that causes the eye muscles to shorten and tighten. This forces the eyes out of proper alignment and may result in double vision.

In some cases, patients may develop a reddening and swelling of the skin that affects the shins and the top of the feet. This is known as Graves' dermopathy.

Graves' disease usually is treated effectively with medications or thyroid surgery or frequently with a capsule composed of radioactive iodine. However, untreated Graves' disease can be fatal.

This condition is named after Robert Graves, an Irish physician who described it in the 19th century. Other terms for Graves' disease include toxic diffuse goiter and diffuse thyrotoxic goiter. Goiter, an enlargement of the thyroid gland, is a symptom of hyperthyroidism.