Many factors may increase your risk for developing hypothyroidism. These include:

• Age and sex. Older adults are more likely to develop hypothyroidism than younger people, and women are more likely than men to develop thyroid disease.⁶
• Family history. Hypothyroidism tends to run in families.
• Previous thyroid problems. Thyroid disease, an enlarged thyroid (goiter), and surgery or radiation therapy to treat thyroid problems increase the likelihood of developing hypothyroidism in the future.
• Some lifelong conditions. Diabetes, an autoimmune disease that causes patches of light skin (vitiligo), pernicious anemia, and premature gray hair (leukotrichia) are seen more often in people with hypothyroidism.
• Iodine deficiency. This is rare in the United States but common in areas where iodine is not added to salt, food, and water.
• Medicines. Some medicines can interfere with normal thyroid function, particularly lithium carbonate, amiodarone (such as Amiodarone, Cordarone, and Pacerone), and interferon alfa (such as Infergen, Rebetron, and Wellferon).

Up to 20% of women older than 60 have mild (subclinical) hypothyroidism; about 2% to 5% of people with subclinical disease develop hypothyroidism every year.^{4, 6} Many of the same factors that increase your risk for hypothyroidism also increase your risk for mild hypothyroidism.