evidence: Hashimoto’s is a common autoimmune condition that is the primary cause of hypothyroidism – an underactive thyroid – in the United States, and millions of people are living with these conditions across the globe. [...] Hashimoto’s thyroiditis is an autoimmune disease that affects the thyroid gland. When you have Hashimoto’s disease, your immune system produces antibodies that mistakenly attack and destroy thyroid cells. Over time, the destruction of thyroid cells results in an underactive thyroid. Hashimoto’s is the most common cause of hypothyroidism in the United States. Because of the resulting hypothyroidism, Hashimoto’s symptoms mirror those of an underactive thyroid. Because Hashimoto’s involves inflammation of the thyroid gland, patients can also have goiter (enlargement of the thyroid gland), discomfort in the neck or throat, and lumps or nodules in the thyroid.