There are plenty of studies proving this. The question is at what amounts. I tried to see if anyone here has tested their epitestosterone levels but was unable to find anything.
Urinary epitestosterone to T ration are used in doping tests. I think on average the ratio is about 1.2:1
Anyway I think this is something very much worth investigating as most of us here are clearly suffering from some kind of androgen deprivation effects.