Yes i notice this especially with letrozole.
My fault that i never tested LH and FSH even while on, because i'm convinced that letro keeps some of the HPTA activity, at least while on low dosage of AAS.
Infact whit letrozole i have a weird reaction. If i take low random dosage, i crash my e2.
If i take full daily 2.5 mg dose, i experience all sides of high e2 (gyno, water, moodiness and so on). I'm talking of pharma letrozole, not ugl. It happens everytime.
I hypotize that letro could increase intratesticular aromatization (or progesterone production) via high levels of gonadotropin.
Wish i've done bloods while taking 2.5 mg of letrozole. Now i don't want to feel like shit and try it again just fo the sake of science.