HGH loses about 8-10% of its potency in a year wghen stored at romm temp. out of light, when it´s reconstituted with ba and water (remeber the white powder ->lyophilsate has some goodies in it, too, like mannitol, stabalizers, phosphate buffers).
It´s just that for human grade medicine only a 2% tolerance is allowed until you have to dispose it all.
I have some pretty good experience with "old" hormones and especially peptides like IGF, Epo, but not slin and hgh, since with up to and >than a year storage at room temp, without loss of potency, or a remarkable loss. (ok, I use for hgh a patented solution which is tested to prevent aggregation of the peptide and stabalizes the structure)