Thyroxine- binding globulin physiology
TBG is a high affinity, low concentration TBP that binds 80% of T3 and 75% of T4. Transthyretin (TTR) and serum albumin are the other TBPs. TBG has a distributive as well as buffering role to stabilise free thyroid hormone concentration supply to target tissues.22 Abnormalities in the TBG can be inherited or acquired, and drugs remain a common cause of acquired alteration.