Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 25416-65-3, Whether you call it L-Thyroxine Sodium, Monosodium L-Thyroxine , Sodium 4-O-(4-Hydroxy-3 -5-di-iodophenyl)-3 -5-di-iodo-L-tyrosine , Sodium Levothyroxine , 3 -5 -3 -5-Tetra-iodo-L-thyronine Sodium or L-Thyroxine Sodium Salt you can be assured the L-Thyroxine Sodium products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.