Causes of Andropause
There may be many factors that contribute to andropause but it is clear that one important reason for an aging man's decline in testosterone is that the testes begin to fail. As men get older, the Leydic cells, which produce most of the testosterone "bursts" in the testes, do not secrete testosterone as frequently and each "burst," on average, includes less testosterone.
Additionally, as men get older, there is a decrease in the hormones that prod the testes to make testosterone. Finally, there is an increase in the conversion (aromatization) of testosterone to other hormones including estradiol and DHT. While testosterone levels decrease with age, DHT levels do not tend to fall as significantly.
