Tell him the truth. Say you abused gear at a young age and you believe your endocrine system is out of balance.
They'll run some blood tests. Maybe send you to an Endo specialist. At your age, natural andropause is uncommon. So they'll try to figure out what the underlying cause is before they wave a script at you.
If he's one of these closeminded, arrogant types, just walk out and go see another doc. I know its a hassle if you have limited docs in your network but you'll find one.
Hopefully your T is normal and he'll write you a script for cialis.