Re: Shrinking testicles
Shrinking testicles is usually a sign of secondary hypogonadism, meaning low testosterone. The pituitary gland in the brain sends LH and FSH to the testicles to tell them to make Testosterone and sperm. If LH/FSH are too low then T and sperm levels will drop and over a long period of time the testicles will shrink...also called testicular atrophy. Just like a muscle would shrink if you stopped using it or exercising it.
Does he have nightime/morning erections? If not, he should have his LH and Testosterone levels checked.