Primary hypogonadism is also known as primary testicular failure, and it is caused by a problem in the testicles. These problems can include injury to the testicle, Klinefelter syndrome, and undescended testicles.
Secondary hypogonadism is caused by a problem with the pituitary or hypothalamus glands. These glands give a signal to the testicles to make testosterone, so testosterone production can be affected. Conditions that cause secondary hypogonadism include pituitary disorders, medications including opioids, type 2 diabetes, and aging.