While short-term experimentation with reasonable doses of gonadorelin probably would not be harmful, I wouldn't recommend it while your HPTA is intact. I think I get benefits from it because my endogenous production had been completely suppressed by TRT. Kisspeptin-10 is a little more interesting, and it has been shown to stimulate the HPTA even in normal individuals. However, too little is known about it to recommend, and you cannot obtain a pharmaceutical-grade product in the U.S. anyway. This leaves enclomiphene and/or Natesto as the best options for someone who wants to get a boost without completely trashing the HPTA.
There are blood tests for GnRH, example, but I'm not sure how useful they'd be given the pulsatile delivery and very short half-life. LH is the better proxy, but it's also pulsatile, which limits the information you get from such measurements. Basically there are three states: very low—as when suppressed by TRT; high, as in primary hypogonadism; and everything in between, which only indicates that you are making some GnRH.
More like 40s, though my 40s were still very good until I made the mistake of using finasteride. By "very good" I mean zero problems with sexual function and libido that's good, but not borderline excessive as in earlier years.
