What are some common causes of hypothyroidism?

There are three common causes of hypothyroidism. Hashimoto's thyroiditis is a chronic autoimmune condition where the body's immune system mistakenly attacks its own thyroid gland. Graves' disease is another autoimmune disease that causes inflammation of the thyroid gland and can sometimes transition into hypothyroidism after treatment or spontaneously. Postpartum thyroiditis is the last, occurring a few months before or after childbirth, and although it usually rectifies itself on its own in few months or years, it sometimes progresses to permanent hypothyroidism requiring a life long treatment.