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.1
  • 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.2
  • 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.4
  • 1 out of every 4,000 infants born worldwide has hypothyroidism. Girls are twice as likely to have hypothyroidism as boys.5

Related Information



  1. Ladenson PW (2005). Thyroid. In DC Dale, DD Federman, eds., ACP Medicine, section 3, chap. 1. New York: WebMD.
  2. 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.
  3. Surks MI, et al. (2004). Subclinical thyroid disease: Scientific review and guidelines for diagnosis and management. JAMA, 291(2): 228–238.
  4. 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.
  5. 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.


Author Caroline Rea, RN, BS
Editor Susan Van Houten, RN, BSN
Associate Editor Tracy Landauer
Associate Editor Pat Truman, MATC
Primary Medical Reviewer Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer Matthew I. Kim, MD - Endocrinology
Last Updated August 25, 2008

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