What is the most common cause of hypothyroidism in the United States?

Hashimoto's thyroiditis is recognized as the most common cause of hypothyroidism in the United States. This is an autoimmune condition where the immune system mistakenly attacks the thyroid gland, leading to inflammation and impaired thyroid hormone production. As a result, the normal functioning of the thyroid is compromised, resulting in a deficiency of thyroid hormones necessary for various metabolic processes in the body.

The prevalence of Hashimoto's thyroiditis, particularly in women and individuals with a family history of autoimmune diseases, contributes significantly to the overall incidence of hypothyroidism in the population. Furthermore, unlike iodine deficiency, which is a leading cause of hypothyroidism in other parts of the world, the U.S. has largely sufficient iodine levels in the diet, diminishing the role of iodine deficiency in this context.

Conditions such as pituitary dysfunction and thyroid surgery can also cause hypothyroidism, but they are less common compared to Hashimoto's thyroiditis. Overall, the autoimmune nature of Hashimoto's and its commonality among patients seeking treatment for thyroid dysfunction solidify its status as the predominant cause of hypothyroidism in the U.S.