The thyroid gland is a butterfly-shaped gland in the front of the neck. Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones. A healthy thyroid produces the hormones thyroxine (T4) and triiodothyronine (T3), which control metabolism. This affects how many calories you burn, how warm you feel, how much you weigh, and how the body handles functions of the cardiovascular, gastrointestinal, and nervous systems. Hypothyroidism results in a slower metabolism and a slower heartbeat.
Hashimoto thyroiditis occurs when the immune system produces antibodies that attack cells of the thyroid gland. This results in thyroid swelling. Other less common causes include hypothyroidism as a result of radiation therapy to the neck for lymphoma, treatment of hyperthyroidism with medication or surgery, and treatment of thyroid cancer with medication, radiation therapy, or surgery.
Other causes of hypothyroidism include:
About 5% of Americans have hypothyroidism. This condition usually occurs in adults. However in some cases, children or infants may have hypothyroidism (called cretinism). Children need treatment as quickly as possible or intellectual disability may result.
Garber JR, Hennessey JV, Liebermann JA 3rd, Morris CM, Talbert RL. Clinical update. Managing the challenges of hypothyroidism. J Fam Pract. 2006;55(6):S1-S8.
Hypothyroidism (underactive thyroid). National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism. Updated August 2016. Accessed February 20, 2017.
Hypothyroidism in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115914/Hypothyroidism-in-adults. Updated July 12, 2016. Accessed February 20, 2017.
Vanderpump MP, Tunbridge WM, French JM, et al. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham survey. Clin Endocrinol. 1995;43(1):55-68.
Last reviewed February 2017 by James P. Cornell, MD
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