Over the last 25 years, the testosterone level of the average American man has decreased by about 24%. This is almost a 1% per year average decline. We are not just becoming a feminist nation; we are becoming a feminized nation. The reason for this overall decline in male hormone levels is poorly understood, but I suspect that it is related to the widespread presence of estrogenic compounds in our society. Many of the plastics and preservatives used in our day-to-day products and foods have an estrogen like effect on the body. 

As the medical profession is becoming more cognizant of the consequences stemming from a diminished testosterone load, an ever increasing number of doctors are starting to use testosterone therapies of one sort or another. Unfortunately, I think most are doing a bad job by failing to acknowledge several important factors.  

To begin, it is important to understand that testosterone produced by the testicles and circulating in the bloodstream is not the only hormone involved in producing our virility. Up to 50% of a young man's virility actually stems from the testosterone which is produced locally within the tissues by a pro-hormone called dehydroepiandrosterone (DHEA). This testosterone is made locally within the tissues, utilized within the same tissues, and never makes it into the bloodstream. Hence, blood tests for testosterone do not detect and measure this portion of androgen. The closest we can come to measuring these locally produced androgen levels correctly is by following the dehydroepiandrosterone sulfate (DHEAS). If all you do is measure testosterone while ignoring the DHEAS, you're going to miss 50% of the factors that influence a man's virility. 

Another problem is that recognition of the conversion of testosterone into estrogen is usually neglected. About midlife, as a man's testosterone level naturally starts declining, his metabolism shifts towards fat. This is because the same cells that produce muscle can also become fat cells. Whether they turn to muscle or fat depends on the chemical environment that is present in the body at any given moment. The decrease in androgens, and the increase in inflammation that accompanies aging, along with a rising percentage of body fat, shifts the preference for the cells towards the production of fat instead of muscle.  

One reason for this trend in cell production is that male abdominal fat contains a high level of an enzyme called aromatase, which converts testosterone into estrogen. The increased estrogen load shifts the metabolism further towards fat, which in turn contains more aromatase, converting more testosterone to estrogen, in a self-perpetuating cycle. As the average, midlife man ages, his testosterone spirals lower and lower while his estrogen level tends to rise. It is not unusual in our clinic to test a husband and wife only to discover that his estrogen is higher than hers. Unfortunately, most doctors never bother to check a man's estrogen level at all. As a consequence of this oversight, a man will often receive a large dose of testosterone, which he promptly converts into estrogen. In an effort to regain his virility, he ends up growing breasts. 

An additional difficulty to watch for is the conversion of testosterone to Dehydrotestosterone (DHT). Men have a variable propensity to shift testosterone into DHT at different points in their life as their enzyme levels are shifting. The failure to address this issue can result in increased hair loss, prostate enlargement, and suboptimal testosterone replacement values. 

If a doctor is going to do testosterone replacement therapy, he needs to address the problem in a comprehensive manner. This means that in addition to measuring testosterone, he also needs to pay attention to estrogen, DHEAS, DHT, and pregnenolone, a related pro-hormone that is often ignored. Pregnenolone can become DHEA, testosterone, estrogen, progesterone, or corticosteroids. Very few physicians doing testosterone replacement have even heard of this important hormone, but if a man’s hormone levels are to be competently evaluated, pregnenolone needs to be measured and monitored along with its metabolic byproducts. Although testosterone is an important hormone, failure to address all of these factors in one comprehensive package may result in doing more harm than good.