The hCG will not stimulate the pituitary it will shut it down further (temporarily) however, it will (as an LH substitute) hopefully stimulate your testicles to produce more T. I suspect your doctor wants to see if your testicles are responsive to the hCG, to help determine to what degree part of your problem is primary hypogonadism. The typical way to stimulate the pituitary to release more gonadotropins is with clomid therapy. I do agree with Nelson regarding checking prolactin, too.