Thyroxine Binding Globulin, Human Serum

The thyroxine binding globulin (TBG, also known as Serpin A7) is a protein responsible for carrying the thyroid hormones thyroxine and 3,5,3'-triiodothyronine in the bloodstream. Mutations in TBG result in a deficiency in the protein, which leads to hyperthyroxinemia.