Is it true that if you receive hcg injections while on testosterone, it will stop your testicles from shrinking? do some men do this while on trt?

For fertility.: Giving testosterone (t) stops the pituitary from making hormones that stimulate t production and sperm production. Since most of the testes is for sperm production, use of t shrinks the testes. Giving injections of HCG and msh (which mimic pituitary hormones) can restore sperm production and fertility in some patients. Due to expense, it is only used for fertility, not just to prevent shrinkage.

Might work: Theory is that HCG will stimulate testicles to continue to produce endogenous testosterone and thus prevent them from shrinkage which can occur from suppression as a direct effect of trt.

Use hCG instead of T: In younger hypogonadal men w/semi-functional testes, we can often stimulate their testes w/prescription injectable HCG alone (not the otc stuff sold for weight loss) to produce t adequate for their needs plus sperm. We employ this when they desire future fertility as well as treatment of low t. Another off-label option is Clomiphene to stimulate lh & FSH release to increase t & sperm production.

Yes: Hcg will stimulate the testicles to make more testosterone. Giving testosterone alone will suppress the signal from the brain to the testicles to make more testosterone. If testicular atrophy is a concern then adding (or even substituting) HCG in place of testosterone can be used to treat low testosterone levels.