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Conditions InDepth: Hypothyroidism

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.
The Thyroid Gland
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Hashimoto's 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 neck radiation for lymphoma and treatment of hyperthyroidism or thyroid cancer with radioactive iodine or surgery.
Other causes of hypothyroidism include:
  • Subacute thyroiditis —This occurs when there is inflammation of the thyroid gland after a viral upper respiratory tract infection.
  • Drugs —Drugs used to treat hyperthyroidism such as lithium (used to treat certain psychiatric disorders), certain cardiac medicines, and other medicines (interleukins, alpha interferon)
  • Medical treatments —Treatments include radiation or surgical removal of part of the thyroid gland (called subtotal thyroidectomy) to treat other thyroid diseases
  • Idiopathic thyroid atrophy —The thyroid tissue shrivels up (atrophies) for unknown reasons
  • Iodine deficiency —The thyroid gland does not get enough iodine to produce thyroid hormone (this is rare in the United States)
  • Iodine excess —Certain foods (such as shellfish) and certain medicines (such as cough medicine) contain large amounts of iodine, which can block thyroid hormone production (rare)
  • Infiltrative illnesses —Cancers and certain infections
  • Pituitary adenoma —A benign tumor of the pituitary gland that can cause a problem signaling the thyroid to make thyroid hormones
  • Postpartum thyroiditis —This condition usually improves but may be long lasting
  • Congenital hypothyroidism —An infant that is born with problems making normal amounts of thyroid hormones
About 5% of Americans have hypothyroidism. This condition usually occurs in adults. But, in some cases, children or infants may have hypothyroidism (called cretinism ). Children need treatment as quickly as possible or intellectual disability may result.
What are the risk factors of hypothyroidism?What are the symptoms of hypothyroidism?How is hypothyroidism diagnosed?What are the treatments for hypothyroidism?Are there screening tests for hypothyroidism?How can I reduce my risk of hypothyroidism?What questions should I ask my doctor?Where can I get more information about hypothyroidism?

References

Garber JR, Hennessey JV, Liebermann JA, Morris CM. Clinical update. Managing the challenges of hypothyroidism. J Fam Pract . 2006;55:S1-8.

Hypothyroidism. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed . Updated November 19, 2012. Accessed November 20, 2012.

Hypothyroidism. National Endocrine and Metabolic Diseases Information Service website. Available at: http://endocrine.niddk.nih.gov/pubs/Hypothyroidism/ . Updated February 27, 2012. Accessed November 20, 2012.

Vanderpump MPJ, Tunbridge WMG, French JM, et al. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham survey. Clin Endocrinol . 1995; 43:55.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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