Hashimoto thyroiditis, otherwise known chronic lymphocytic thyroiditis, is the most common cause of underactive thyroid disease, or hypothyroidism, in the United States. It affects more than 15 million people in the US and tends to be seen more frequently in women, but men can also be affected. Hashimoto thyroiditis is an autoimmune condition, which means that the immune system has been triggered to start working again the thyroid gland and can potentially decrease its function.
