you stop vital body functions from taking place, GHlevels cant relese properly if you dont have enough estrogen... lots of stuff, granted men really dont need that much, but we wouldnt have it all together if we didnt need it in someway... letrzl will just lower your estrogen levels, its good to keep for sides if they pop up during a cycle, it basically shuts down estrogen, not a blocker, but a stopper! so i woulndt use it pct, nolva is and estrogen blocker and raises LH levels combined with clomid, there the only thing id ever use PCT, maybe little HCG, but that depends on kinda of cycle i did... luck man...