What is Hashimoto's disease?

Hashimoto's disease is a condition in which your immune system mistakenly attacks your thyroid gland, at first increasing thyroid hormone levels and then preventing your thyroid from producing effective hormone. Untreated Hashimoto's can also cause an enlarged heart and even coma.

Autoimmune thyroiditis is also known as Hashimoto's thyroiditis or chronic lymphocytic thyroiditis, and is the most common cause of hypothyroidism. The majority of patients with Hashimoto's have antibodies to thyroid peroxidase (TPO). These antibodies cause destruction of thyroid cells that leads to fewer cells making thyroid hormone. Most patients with Hashimoto’s disease will ultimately require thyroid hormone supplementation. In addition to causing an underactive thyroid, sometimes patients can get enlargement or swelling of their thyroid which can cause pain and pressure in their neck which can lead to difficulty swallowing.
Risk factors for Hashimoto's thyroiditis include female gender, personal or family history of other autoimmune disease.
For more information go the endocrinediseases.org:
Diseases of thyroid function: Hypothyroidism