Thyroid autoantibodies are antibodies that develop when an immune system mistakenly targets components of your thyroid gland or thyroid proteins, leading to inflammation of the thyroid (thyroiditis), tissue damage, and/or disruption of thyroid function. Lab tests detect presence and measure the quantity of specific thyroid autoantibodies in the blood. The thyroid is a small, butterfly-shaped gland that lies flat against the windpipe in your throat. The primary hormones that it produces, thyroxine (T4) and triiodothyronine (T3), are vital in regulating the rate at which the body uses energy (metabolism). The body uses a system in which thyroid stimulating hormone (TSH) stimulates the thyroid to produce T4 and T3. This system helps maintain a stable amount of the thyroid hormones in the blood. When thyroid antibodies interfere with this process, it can lead to chronic conditions and autoimmune disorders associated with hypothyroidism or hyperthyroidism. Includes: TGAb - A thyroglobulin antibodies (TgAb) test is used to check blood levels of antibodies the body has made against the compound thyroglobulin. Thyroglobulin is a protein produced and used by the thyroid gland (the small, butterfly-shaped gland in the neck) to make the hormones triiodothyronine (T3) and thyroxine (T4), both of which help control metabolism and growth. TPO - A thyroid peroxidase (TPO) antibodies test checks the levels of antibodies made against the compound thyroid peroxidase (TPO) in the bloodstream. Thyroid peroxidase is an enzyme produced by the thyroid gland. The thyroid is a small, butterfly-shaped gland in the neck that uses iodine, with the help of the enzyme TPO, to create the hormones triiodothyronine (T3) and thyroxine (T4), both of which help control metabolism and growth. Antibodies are proteins made by the immune system, usually to fight bacteria, viruses, and toxins that enter or contact the body.