Liothyronine-d4 (Triiodothyronine-d4) is the deuterium labeled Liothyronine (HY-A0070A). Liothyronine is an active form of thyroid hormone. Liothyronine binds to thyroid hormone receptors TRalpha and TRbeta with vs of 2.33 and 2.29 nM for hTRalpha and hTRbeta, respectively. Liothyronine also binds to PVR and blocks the interaction of TIGIT/PVR[1][2][3].