According to Chinese Medicine, most functional symptoms are rooted in the Kidney/Bladder for men.

The Kidney/Bladder is the reservoir of Life Force energy. This is the energy passed on from your parents. The quality and quantity of the Kidney/Bladder energy depend upon what was received and how you expend this energy in daily life. This energy peaks around 16 during puberty and steps down in 8-year cycles until the age of 64. This is the time when, if balance/harmony have not been maintained, you may see signs of “manopause."