Graves disease or hyperthyroidism is a condition that causes your thyroid gland to make too much thyroid hormone, or become over-active.
The thyroid gland is located in the neck and is shaped like a butterfly. There are several hormones made by the thyroid gland that are important for growth and development. These same hormones also help with your energy level and help the heart, liver, kidneys and skin work correctly. These important hormones are called thyroxin (T4) and triiodothyronine (T3).
The thyroid gland is told to make T4 and T3 by another hormone which is made in the brain. This hormone is called thyroid-stimulating hormone (TSH).
When a child's TSH is low, the body might be making special cells that act like TSH. These cells are called antibodies. In this case, the antibodies tell the thyroid gland to make more T3 and T4. When this happens a child has Graves disease or hyperthyroidism.
Graves disease is more common in teenage girls, but can be found in boys and girls of any age.