What Causes Hypothyroidism?
Hypothyroidism is a very common condition. Approximately 3% to 4% of the U.S. population has some form of hypothyroidism. This type of thyroid disorder is more common in women than in men, and its incidence increases with age. Examples of common causes of hypothyroidism in adults include Hashimoto's thyroiditis, an autoimmune form of overactive thyroid, lymphocytic thyroiditis, which may occur after hyperthyroidism (underactive thyroid), thyroid destruction from radioactive iodine or surgery, pituitary or hypothalamic disease, medications, and severe iodine deficiency.