Hashimoto's disease is an autoimmune disorder that can cause hypothyroidism, or underactive thyroid. Do you or a loved one suffer from hypothyroidism? If so, chances are you may also suffer from the autoimmune disease Hashimoto's. This disease, otherwise known as Hashimoto's thyroiditis, is where your immune system attacks your thyroid and can cause serious conditions and symptoms throughout your body. What most people don't know is that Hashimoto's treatment can be very different than a hypothyroidism diagnosis and it is important to be diagnosed properly and be informed of your options for treatment.