It is actually a GnRH agonist.
However there is a study where they replaced GnRh with HCG (it was in animals) but the hcg roup actually functioned BETTER than the GnRh group. this result leads me to believe that it certainly must function as a true Gnrh ...not just an anlog. Either that or it is so potent at triggering GnRh release that even with 0 GnRH endogenously present injecting it causes a higher level of function than GnRh on its own.Thus its bility to function even in a shutdown / high levls of test present scenario.