evidence: Print Overview Thyroid gland Enlarge image Close Thyroid gland Thyroid gland The thyroid gland sits at the base of the neck. Hashimoto's disease is an autoimmune disorder affecting the thyroid gland. The thyroid is a butterfly-shaped gland located at the base of the neck just below the Adam's apple. The thyroid produces hormones that help regulate many functions in the body. An autoimmune disorder is an illness caused by the immune system attacking healthy tissues. In Hashimoto's disease, immune-system cells lead to the death of the thyroid's hormone-producing cells. The disease usually results in a decline in hormone production (hypothyroidism). Although anyone can develop Hashimoto's disease, it's most common among middle-aged women. The primary treatment is thyroid hormone replacement. Hashimoto's disease is also known as Hashimoto's thyroiditis, chronic lymphocytic thyroiditis and chronic autoimmune thyroiditis.Products & ServicesA Book: Mayo Clinic Family Health BookNewsletter: Mayo Clinic Health Letter — Digital EditionShow more products from Mayo Clinic SymptomsHashimoto's disease progresses slowly over the years. You may not notice signs or symptoms of the disease.