Your LH level will come back either very low or non existant signaling somethings up, he can question you but if you deny using then he cant really question the fact. I told my endo i had used years ago but nothing since 2005.
The only reason i was using (200mg/week at the time) was because back in 2009 at the begining of my illness my Test levels came back low but just 1 point within range. Here in the UK if your in range they wont treat you - full stop, no looking at how you feel or nocturnal/morning erections etc, just no treatment:banghead:
So i began to treat myself for 12 months till i decided i wanted to go legit so began on the route your now taking.
4 weeks off Enth and my 1st blood test came back just under a low reading (i dont have my papers to hand so cant give you the figures) so the Endo refused to treat me again unitil a further test had been done in 12 weeks.
Went home and started on test prop at 15mg/day to cover me for the 12 weeks.
7 days before my next blood draw i dropped the prop and my next results were slightly lower than last results. LH was obviously still non existant, Endo still questioned me about what supplements or drugs i may have been using.
Again admitted nothing apart from previous usage back in 2005. Endo still puzzled but agreed to start me on gel as all my blood work was perfectly fine and go from there. (UK endos like to start you off on the gel to see how you react then later switching you onto injections for cost and convenience).
My only advice would to be take at least 6 weeks off the Enth before the blood draw and also consider donating blood around the same time to address any problems you may have with raised blood cell counts etc.
Good luck!