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Epidemiologic analysis of a large population reported that about 1 of 30 (3.2%) people in the United States are currently affected by autoimmune diseases. Graves disease, type 1 diabetes, pernicious anemia, rheumatoid arthritis, Hashimoto thyroiditis, and vitiligo are the most prevalent such conditions, accounting for 93% of affected individuals. A more global approach at calculating prevalence led to a corrected estimate between 7.6% and 9.4% of the world’s population as affected by autoimmune diseases (2.5 in 30 people worldwide).
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These autoimmune diseases have traditionally been looked upon as forming a spectrum. At one end are found organ-specific diseases with organ-specific targets. Hashimoto thyroiditis is an example in which a specific lesion affects the thyroid (lymphocytic infiltration, destruction of follicular cells) and autoantibodies are produced with absolute specificity for thyroid proteins. At the other end of the spectrum are the systemic autoimmune diseases, broadly belonging to the class of rheumatologic disorders. Systemic lupus erythematosus is an example of a disease characterized by widespread pathologic changes and a collection of autoantibodies to DNA and other nuclear constituents of all cells. Many organ-specific autoimmune diseases are autoimmune endocrinopathies. Furthermore, most endocrine glands are subject to autoimmune attack including the adrenals (autoimmune Addison disease), gonads (autoimmune oophoritis), pancreas (type 1 diabetes), pituitary (autoimmune hypophysitis), and thyroid (autoimmune thyroid disease) (Table 2–1).
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