What is the risk associated with suppressing fsh/lh when using hcg to increase testosterone in men?

Minimal: Let's put it this way: using any type of t to replace/fix hypogonadism/andropause will also suppress fsh/lh. But more importantly, taking t will shut down testicular function from lack of fsh/lh. Using HCG to stimulate the testes to produce more t & sperm will result in negative feedback @ pituitary, thus suppress lh/fsh. But at least your testes are functioning fully. It's off-label but it works.

Not much: Nomal fertility depends on a balance of fsh and lh. Hcg just provides lh and so fsh may fall, impairing fertility. The key is to not use unopposed treatment for long periods of time.