Testosterone is the hormone responsible for deep voices, muscle mass, and facial and body hair patterns found in males. As men get older, the level of testosterone in the body and production of sperm gradually becomes lower, and they experience physical and psychological symptoms as a result of these low levels. This is part of the natural aging process and it is estimated that testosterone decreases about 10% every decade after men reach the age of 30.
Andropause is a condition that is associated with the decrease in the male hormone testosterone. It is unlike menopause in that the decrease in testosterone and the development of symptoms is more gradual than what occurs in women. Approximately 30% of men in their 50s will experience symptoms of andropause caused by low testosterone levels. A person experiencing andropause may have a number of symptoms related to the condition and could be at risk of other serious health conditions such as osteoporosis without proper treatment.
The decrease in testosterone is an important factor in men suspected of having andropause. However, as men age, not only does the body start making less testosterone, but also the levels of another hormone called sex hormone binding globulin (SHBG), which pulls usable testosterone from the blood, begins to increase. SHBG binds some of the available testosterone circulating in the blood. The testosterone that is not bound to the SHBG hormone is called bioavailable testosterone, meaning it is available for use by the body.
Men who experience symptoms associated with andropause have lowered amounts of bioavailable testosterone in their blood. Therefore, tissues in the body that are stimulated by testosterone receive a lower amount of it, which may cause various physical and possibly mental changes in a person such as mood swings or fatigue.