It is not clear whether aging itself or the disorders associated with aging cause the gradual changes that occur in men's sexual functioning. The frequency, duration, and rigidity of erections gradually decline as men age (see Erectile Dysfunction). Levels of the male sex hormone ( testosterone) tend to decrease, reducing sex drive (libido). Blood flow to the penis decreases. Other changes include
Beginning at about age 20, the production of testosterone (the main male sex hormone) in men usually begins to decrease an average of 1 to 2% per year. The period later in life when testosterone production has decreased enough to cause significant symptoms is sometimes described as male menopause, or andropause. However, the gradual hormone decline in men differs greatly from what women experience in menopause, during which female hormones almost always decline rapidly over just a few years. The rate of testosterone decline varies greatly among men. Some men in their 70s have testosterone levels that match those of the average man in his 30s.
Whether young or old, men with low testosterone levels may develop certain characteristics associated with aging, including decreased libido, decreased muscle mass, increased abdominal fat, thin bones that easily fracture (osteoporosis), decreased energy level, slowed thinking, and a low blood count (anemia). Low testosterone levels also increase the risk of coronary artery disease.
Many men with normal testosterone levels are interested in taking testosterone to slow or reverse development of characteristics of low testosterone. However, currently testosterone replacement therapy (TRT) is recommended only for men with both symptoms of low testosterone and abnormally low blood levels of testosterone, a condition called hypogonadism. Recent studies have found conflicting evidence suggesting a possible increased risk of heart attack and stroke in men who take TRT.
Testosterone treatment may rarely have certain side effects, such as snoring, increase in symptoms of urinary tract blockage (usually caused by benign prostatic hyperplasia), mood changes, acne, blood clots, and breast enlargement. Testosterone sometimes causes the body to make too many red blood cells, possibly increasing the risk for various disorders, such as blood clots and strokes.
Currently, testosterone treatment is thought to have no effect on the development or progression of prostate cancer. However, this subject is not entirely understood, and men should talk with their doctors about their risk of developing prostate cancer.
Men taking testosterone need to be checked every few months for changes in their blood count and for prostate cancer. Such testing may detect cancers early, when they are more likely to be curable. Some men with prostate cancer may take testosterone treatment, but they should be checked even more frequently by their doctor.