When using exogenous hormones, the endogenous shut down. LH and FSH will go to damn near 0. Like SD mentioned, you can use hcg to mimic LH and produce more sperm thus resulting in larger nuts but even hcg is suppressive so using it in pct is counterproductive
Mucuna Pruriens has been shown in studies to boost LH output, as well as dopamine...
http://www.ergo-log.com/mucunatest.html