25416-65-3 (MONOSODIUM HYDRATE) 51-48-9 55-03-8 (ANHYDROUS SODIUM SALT) AIDS-003357 AIDS003357 L-Thyroxine Levothroid (*Sodium salt*) Levothyroxine O-(4-Hydroxy-3,5-diiodophenyl)-3,5-diiodotyrosine Synthroid (*Sodium salt*)