The counterpart to the female menopause is called the andropause (or the "male menopause"). Testosterone levels in men remain relatively constant until about the age 50, at which time they begin to fall slowly. However, the decline in male hormone production is much more gradual than the decline in female hormone production.

Testosterone may be beneficial in many ways. It may enhance libido, decrease heart disease risk, increase lean body mass and prevent osteoporosis. Testosterone may also lower total cholesterol and LDL, and decrease insulin resistance. As men age, the balance between testosterone and estradiol might tilt in favour of estradiol production. The pituitary hormone responsible for stimulating testosterone is LH (luteinizing hormone). Too much estradiol may decrease the level of LH and, therefore, the level of testosterone.

Ten years ago testosterone was thought to be beneficial only for younger men for whom it conferred increased muscle mass, stronger bones, powerful sexual urges, and the three V's of vim, vigour and vitality. For older men, it was usually avoided due to its association with such age-related complaints as male-pattern baldness, urinary difficulties and prostate cancer.

About the same time a metabolite of testosterone, dihydrotestosterone (DHT), was discovered. Levels of testosterone in young men are quite high, while levels of DHT are low. The enzyme responsible for the conversion of testosterone to DHT, 5-alpha reductase, becomes more active with age. Thus the levels of testosterone decrease while the levels of DHT increase.

Activity became focused on trying to block the conversion of testosterone into DHT. An effective 5-alpha reductase inhibitor was developed and it received FDA approval for the treatment of benign pro-static hypertrophy (BPH), one of the main causes of the urinary difficulties experienced by older men. This treatment worked very well; unfortunately, five percent of the men who use this 5-alpha reductase inhibitor experience sexual side effects including decreased libido, impotence and ejaculatory disorders. In addition, a study at the University of Southern California found that among men at high risk for prostate cancer, those who used this 5-alpha reductase inhibitor had an 800% higher chance of developing prostate tumours than those men who took nothing at all.

It appears that neither testosterone nor dihydrotestosterone may be the problems, but oestrogen. It is surprising to learn that the average 60-year-old male has more circulating oestrogen in his bloodstream than the average 60-year-old female. Although oestrogen might have numerous beneficial effects for menopausal women, excess amounts in "andropausal" men may appear to be catastrophic.

The conversion of testosterone to estradiol takes place under the influence of the enzyme aromatase. Testosterone and androstenedione are both "aromatizable" to estradiol, while DHT is not. Some endocrinologists and other physicians believe that many of the prostate difficulties experienced by men as they age are the result of imbalances between levels of estradiol and DHT. When a complete hormone panel is done, including free and total testosterone, DHT, sex hormone binding globulin (SHBG), estradiol, progesterone and a PSA test for prostate, a rational treatment plan can be devised.

In many cases, levels of oestrogen are found to be elevated. If this happens, it is possible to block aromatase activity, so the chances that the testosterone given will be converted to even more oestrogen may be reduced.

Currently there are several aromatase inhibitors on the market for prescription use as treatments for breast cancer. These aromatase inhibitors might block the conversion of testosterone to oestrogen in men as well. There is also a natural aromatase inhibitor called chrysin. It can be found alone and in combination with other supplements used to improve prostate health, such as saw palmetto. The main action of saw palmetto is to block the 5-alpha reductase from turning testosterone into DHT. There is some evidence that saw palmetto might also serve as an aromatase inhibitor.