Not available,(S)-2-Amino-3-(4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodophenyl-2,6-d2)propanoic-2-d acid,Labeled Levothyroxine, intended for use as an internal standard for the quantification of Levothyroxine by GC- or LC-mass spectrometry.,Levothyroxine Stable Isotopes