Men can experience a condition like menopause called andropause where men experience low testosterone levels. Low testosterone (male hypogonadism) is a condition in which the testes (testicles, the male reproductive glands) do not produce enough testosterone (a male sex hormone). As men age, the amount of testosterone gradually drops. The natural decline starts after age 30 and throughout his life. It is difficult to define normal testosterone levels because levels vary throughout the day and can be affected by obesity, nutrition, alcohol consumption, medications, and illness.