Male hormone cycle: how does it work?
The major androgens in the male human body are dihydrotestosterone (DHT) and testosterone. The testicles make most of the androgen, but a fair quantity of them are also made by the adrenal glands.
Levels of testosterone vary significantly — generally, older males have lower levels of testosterone than younger males. There is a gradual decline in the levels of testosterone throughout adult life; the level declines by about one percent per year after the age of 30, on average.