Hyperthyroidism is too much thyroid hormone in the blood. The thyroid gland is in the front of the neck. It makes two hormones that control metabolism, such as:
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Graves disease is the most common. It causes the immune system to make antibodies that cause the thyroid gland to make too much hormone.
Hyperthyroidism can also be from:
Treating hyperthyroidism can lead to hypothyroidism. This is when the gland does not make enough hormone.
Bahn RS, Burch HB, Cooper DS, et al. Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists. Endocr Pract. 2011 May-Jun;17(3):456-520, also published in Thyroid 2011 Jun;21(6):593.
Hyperthyroidism (thyrotoxicosis). Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/thyroid-disorders/hyperthyroidism. Accessed May 17, 2019.
Hyperthyroidism and other causes of thyrotoxicosis. EBSCO DynaMed website. Available at:https://www.dynamed.com/topics/dmp~AN~T116479/Hyperthyroidism-and-other-causes-of-thyrotoxicosis. Updated November 1, 2018. Accessed May 17, 2019.
Primary hyperthyroidism. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: http://www.niddk.nih.gov/health-information/health-topics/endocrine/primary-hyperparathyroidism/Pages/fact-sheet.aspx. Updated March 2019. Accessed May 17, 2019.
Thyroid disorders. Healthy Women website—National Women's Health Resource Center website. Available at: http://www.healthywomen.org/condition/thyroid-disorders. Accessed May 17, 2019.
Last reviewed March 2019 by EBSCO Medical Review BoardJames P. Cornell, MD Last Updated: 5/20/2019