Use of testosterone replacement and benefits
A recent Veteran’s Administration study published in JAMA, the Journal of the American Medical Association, has received much media attention, raising fears regarding the use of testosterone replacement in aging men. The study had multiple flaws that limit its usefulness. Some of these flaws include:
The results of this study are contrary to the vast majority of studies supporting the benefits of testosterone replacement. Other studies using better methodology have concluded that:
As Cenegenics physicians, we strive to give you the latest information regarding our therapies. An example is putting studies like this into perspective.
Not only do we want the best care for our patients, as patients ourselves, we want to be sure we are doing the right thing for our own health. You can count on Cenegenics for accurate, unbiased information. Our continued mission is to provide our elite patients with the best medical care possible.
So what’s the take home message?
An overwhelming amount of medical literature supports the positive benefits of testosterone replacement, even in patients with coronary disease and heart failure.
While the study raises the possibility that a subset of elderly patients with significant cardiovascular disease could conceivably have an increased risk of events, this risk could be minimized or eliminated by the use of 81mg of aspirin.
Testosterone replacement should be given and followed by a physician experienced in its use.
Testosterone replacement should be accompanied by lifestyle modifications to achieve maximum benefit.
More About Testosterone
Testosterone’s effects are body wide. Because about 30% of testosterone is bound to sex hormone binding globulin (SHBG), it is not biologically available. It is the 1% to 2% of free testosterone (free T) that is physiologically active. Its presence is (or lack thereof) manifest in multiple organ systems, with testosterone associated with retention of desirable values of actuarial disease risk and with well-maintained body composition. The impact of falling testosterone levels upon many of these parameters is examined as part of this presentation.
The decline in testosterone levels associated with normal aging is multi-factorial, with no one event being the most common finding in a given patient population. These events can be measured as the levels of serum testosterone begin to change. Studies suggest that about 20% of men in their 60s, and half of men in the 80s have low serum testosterone levels. Concommintently, metabolic syndrome (MetS), and its conditions of obesity, type 2 diabetes mellitus, and hypertention increase the risk of hypergonadism. Not only MetS impacts men’s health, but adverse environmental factors are attributed to testosterone deficiency.5 6
Anatomy and physiology
Anatomy and physiology change. There is a decline in the absolute number of Leydig cells in the testes; each remaining cell shows a decline in testosterone production. There is an associated decline in testosterone synthesis proteins and enzymes, evidenced in aging Leydig cells. The net result is the presence of fewer cells, lower production per cell, and loss of previous response to stimulatory signals.
Additionally, the pituitary gland loses the ability to coordinate pulsatile LH secretion patterns and becomes more random. The loss of coordinated LH pulses—rather than a decline in over-all amount of LH production—is associated with diminished testosterone production.
Another factor affecting the functional availability of testosterone is the age-related increase in SHBG. SHBG levels increase with age, regardless of intervention, and lower the amount of unbound (free) testosterone. These proteins “cling” to testosterone. Even though testosterone may be present, it is not “free” or biologically available to do its work. Increasing SHBG levels, therefore, reduces free testosterone to an even greater extent than the reduction seen in total testosterone. These factors, act additively to lead to less total testosterone production, and an increase in binding protein levels, further depressing free/functional testosterone levels.
Obesity, however, is associated with decreased SHBG productions, then increases total T, but decreases free T. Although this might seem contradictory, other factors exist. Obesity is associated with increased inflammatory cytokine production and increased aromatization to estradiol in peripheral fat tissues. Consequently the pituitary production of gonadotropins is decreased which then decreases testicular production of T.
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