I was talking with my wife last night about some of the hcg questions that I've seen on the forum, and she stumped me with a question of her own: Why don't more men on TRT use HCG to prevent testicular atrophy and infertility? When I first started posting on Meso, I asked a similar question ("Is it possible to stay on a cycle indefinitely without suppressing if you took enough HCG, clomid and adex?"). However, I didn't have a good understanding of how HCG worked at that time; I mistakenly thought that HCG could be used to prevent hypothalamic / pituitary suppression, and that it would bring LH and FSH up. Since then, I've researched HCG in the journals, and I feel like I understand it pretty well at this point. Still, I was only able to answer her question partly. I explained to her that since HCG is similar to LH, HCG is only useful in men whose testes can respond to LH. This limits the usefulness of HCG to the group of men that have secondary hypogonadism. Still, I couldn't really explain why more men with secondary hypogonadism don't use HCG. I expect that some men on TRT are bothered by the shrinkage, but more still would be bothered by the infertility. HCG seems to take care of both problems. On the cons side, there's the hassle of having to give yourself shots, and there's the potential for high E2. However, it looks like if you use small, daily doses of HCG, you can pretty much avoid the E2 spike entirely (see Differential Effect of Single High Dose and Divided small Dose Administration of Human Chorionic Gonadotropin on Leydig Cell Steroidogenic Desensitization -- SMALS et al. 58 (2): 327 -- Journal of Clinical Endocrinology & Metabolism). On the pros side, it prevents testicular atrophy and infertility, and thus can make the transition from using TRT to not using TRT much less difficult --- atrophied testes don't respond right away to the body's own LH, so keeping them functional with HCG makes it so that they can "hit the ground running" so to speak. Am I missing something?