The labeled T3 (*T3) is able to bind to the excess binding sites on TBG; as a result, the amount left over to bind to the resin (or other binder such as talc or dextran-coated charcoal) is lower than normal. The serum total T4 is high; the T3-uptake and THBR are low, and the serum free T4 index is normal.
