SERPINA7 (Thyroxine-binding globulin, TBG): SERPINA7 is a carrier protein produced mainly in the liver that circulates in the bloodstream. It binds and transports thyroid hormones — primarily thyroxine (T4) and triiodothyronine (T3) — ensuring their stable levels and delivery to tissues. This glycoprotein is essential for regulating the distribution of thyroid hormones, which influence metabolism, growth, and development. Changes in SERPINA7 levels or mutations in its gene can affect hormone availability and thyroid-related functions.