What causes hyperthyroidism?
In more than 70% of cases, hyperthyroidism is caused by an autoimmune disorder called Graves’ disease. Normally, antibodies produced by the immune system help protect the body against viruses, bacteria and other foreign substances. An autoimmune disease is when your immune system produces antibodies that attack your body's tissues and/or organs. With Graves' disease, antibodies produced by the immune system stimulate the thyroid, making it produce too much hormone. Doctors think Graves’ disease may run in families. It is most common among young women.
Two other common causes for hyperthyroidism include:
- Hyperfunctioning thyroid nodules. One or more nodules or lumps in the thyroid grow and increase their activity so that they make too much hormone.
- Thyroiditis. A problem with the immune system or a viral infection causes the thyroid gland to become inflamed and produce extra thyroid hormone that leaks into the bloodstream.
Written by familydoctor.org editorial staff