In this article. Also called Hashimoto's disease, Hashimoto's thyroiditis is an autoimmune disease, a disorder in which the immune system turns against the body's own tissues. In people with Hashimoto's, the immune system attacks the thyroid.eople who get Hashimoto's often have family members who have thyroid disease or other autoimmune diseases. This suggests a genetic component to the disease. Hormones. Hashimoto's affects about seven times as many women as men, suggesting that sex hormones may play a role.