What Causes Overactive Thyroid?
A number of different conditions can cause overactive thyroid
. Some of these can occur within the thyroid gland itself, including:
Other overactive thyroid causes can be found outside the thyroid gland. They include:
- Consuming too much iodine (iodine-induced overactive thyroid)
- Taking too much synthetic thyroid hormone
- A pituitary adenoma.
A Closer Look at Causes Within the Thyroid
Several possible causes of an overactive thyroid are explained in the following sections.
Graves' disease is the most common cause of overactive thyroid in the United States. This is a type of autoimmune condition, which means the body's immune system attacks its own healthy cells and tissues for some unknown reason.
In Graves' disease, the immune system makes an antibody called thyroid-stimulating immunoglobulin (TSI), which mimics thyroid-stimulating hormone (TSH) and causes the thyroid to make more hormone than the body needs.
Graves' disease affects 2 percent of all women at some point in their lives. It tends to affect women between the ages of 20 and 40, although it does occur in infants, children, and the elderly of both sexes.
Graves' disease is also known as toxic diffuse goiter.