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Who Is Affected by Hypothyroidism

Topic Overview

Hypothyroidism is the most common type of thyroid problem. The incidence tends to increase with age, with women older than 60 at highest risk. Hypothyroidism tends to run in families.

  • Hypothyroidism occurs in 4 to 5 out of 100 people in the United States.3
  • Hypothyroidism is more common in older people than in younger and more common in women than in men.
  • In iodine-deficient areas of the world, 10 to 20 times more people have hypothyroidism than in the United States.1
  • Mild (subclinical) hypothyroidism affects up to 20 out of 100 of women older than 60.3
  • About 2 out of 100 of pregnant women in the United States develop hypothyroidism.3
  • 1 out of every 4,000 infants born worldwide has hypothyroidism. Girls are twice as likely to have hypothyroidism as boys.2

Related Information



  1. Ladenson P, Kim M (2008). Hypothyroidism section of The thyroid. In L Goldman, D Ausiello, eds., Cecil Medicine, 23rd ed., pp. 1700–1703. Philadelphia: Saunders Elsevier.

  2. LaFranchi S (2007). Hypothyroidism section of Disorders of the thyroid gland. In RE Kliegman et al., eds., Nelson Textbook of Pediatrics, 18th ed., pp. 2319–2327. Philadelphia: Saunders.

  3. Brent GA, et al. (2008). Hypothyroidism and thyroiditis. In HM Kronenberg et al, eds., Williams Textbook of Endocrinology, 11th ed., pp. 377–409. Philadelphia: Saunders Elsevier.


ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerMatthew I. Kim, MD - Endocrinology
Last RevisedJuly 16, 2010

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