When in life do the signs of male menopause begin?

Andropause: Unlike menopause, due to steady & slow decline of circulating testosterone, so sudden change. Men tend to have 1% lower testosterone/year from age about 30 years doen to 50% youth levels age 70. How much is due to lower testosterone, lower sex drive, erectile problems, loss of body hair etc & how much from natural ageing is debateable. Thus tremendous age disparity, as low as 40 or as high as 70.

Andropause: In men over 45 testosterone levels can decrease to much lower than they were as young men. This is called andropause. Many men will have fatigue, grumpiness, loss of muscle and stamina, and loss of sex drive. Symptoms should be evaluated for consideration of testosterone replacement.