Hashimoto's Thyroiditis, an autoimmune condition in which the body's antibodies attack the thyroid, a butterfly shaped gland located in the neck, leads to underactive thyroid or hypothyroidism. According to the Mayo Clinic, Hashimoto's is the number one cause of hypothyroidism in the U.S.
The thyroid is a small gland in the front of your neck that produces hormones affecting your metabolism. When it malfunctions, it can suffer thyroiditis, which exists in several different forms. One type of thyroiditis is Hashimoto's disease, a common ailment which, though debilitating, can be regulated with daily medication.
Hashimoto's thyroiditis is the most common cause of hypothyroidism, or an underactive thyroid, outside of regions which do not have sufficient iodine in the diet. A type of autoimmune disorder, the disease causes the immune system to attack the person's thyroid gland and damage it. Hashimoto's thyroiditis affects mostly women. People with this condition must stay on medication throughout their lives.