Thyroxine Binding Globulin Test - Thyroxine Binding Globulin (TBG) Test

Test that measures Thyroxine-Binding Globulin (TBG) concentration in serum. It is the main protein that binds thyroid hormones (T4 and T3) and transports them in bloodstream. Changes in TBG level affect reading of "total" thyroid hormones, while "free" active hormones remain stable.