“Androgen use and abuse is increasing in our society, either for therapeutic or recreational reasons”. —Vascular Health Risk Management 2008


If Testosterone in men is simply ED and low libido, then Testosterone is nothing more then recreation.  But, if low Testosterone is associated with metabolic dysfunction and this metabolic dysfunction has implications for disease development, then low Testosterone and thus Testosterone therapy has a therapeutic role in a man’s Health.


Does low Testosterone increase Cardiovascular disease in men?  Does Testosterone therapy increase Cardiovascular disease in men?  Is low Testosterone even a problem in men, or is it simply a marketing fallacy?  Is Testosterone the effect or the cause?  Is there a timeline of low Testosterone in the development of disease for men?  Are men simply Testosterone fueled erections as marketing implies or is Testosterone simple one piece of the puzzle in men’s health?  Lets look for answers to these questions in science, not in opinion.   Is Testosterone the cause, the effect, or both?   The answer is yes, yes, and you guessed it—yes.



Testosterone levels have declined by 15% from 1987 to 2004

Travison TG et al. A population-level decline in serum Testosterone levels in American men. J Clin Endocrinol Metab. Oct 24 2006.

First, I want to review the evidence of the problem.   The obvious first place to look is Testosterone levels in men.   Testosterone levels are on the decline in men.  What is the evidence?  A 2006 Journal of Clinical Endocrinology and Metabolism found that Testosterone levels declined 15% in American men from 1987 to 2004 (figure left).  A more recent 2012 study found a 19% decline in Testosterone levels over a 20 year study.  This 19% decline was more than twice the estimates pre-study.  Studies have shown that the average man’s Testosterone levels decline by 47% over their lifespan—this from a study that validated salivary Testosterone levels in the diagnosis of low T in men.  Think of that, we die half the men we were.  This decline in Testosterone is not a sudden drop, but a gradual decline.  The annual decline of Total Testosterone in men is 1-2%.  The Massachusetts Male Aging Study found that free Testosterone levels declined at a greater clip than total Testosterone,  at 2-3% annually, with a decline of total Testosterone at 1.6% annually.  A study of Finnish men recently born


Perheentupa A et al. A cohort effect on serum testosterone levels in Finnish men. Eur J Endocrinol. Feb 1 2013.

Perheentupa A et al. A cohort effect on serum testosterone levels in Finnish men. Eur J Endocrinol. Feb 1 2013.

matched against older study groups (cohort) of men (figure right) found a significant decline in free Testosterone and Sex Hormone Binding Globulin (SHBG) in the more recently born group.  Sex Hormone Binding Globulin is a protein that transports Testosterone and other sex hormones.  One might think that this decline is merely a product of aging, but a study in Human Reproduction in 2002 found that the greatest decline of Testosterone has occurred in American men < 30 years old.  That should open the eyes of every young man.


Is Testosterone therapy safe?   Why even test for Testosterone levels if the treatment is worse than the mere presence of low Testosterone?  The short answer to the question is that Testosterone is safe.   That statement on the safety of Testosterone therapy requires a few caveats.  First, simply following Testosterone levels is woefully inadequate for evaluation.  Whether following initial evaluation or follow up from therapy,  Testosterone is just one piece of the hormone symphony for men.  The body does many things with Testosterone.  Testosterone made or Testosterone given does not just stay as Testosterone.  Is the body following textbook physiology with Testosterone therapy?  If low T is present, the likely answer to the textbook physiology question is NO.  Why is low T even present to begin with?  If the cause is high Estrogen production from belly fat (see Man Boob Nation), which comes from Testosterone, then adding Testosterone therapy is like throwing gasoline on the fire.  The second caveat is physiologic dosing.  Studies have shown that peak Testosterone production occurs in men at age 22-25.  The amount may surprise you.  Peak production of Testosterone for men is only 5-10 mg daily.  If a man doesn’t make 100 mg daily at 22-25 when he is chasing everything with a skirt, then he sure doesn’t need 100 mg at age 40+.  Check out my previous posts “Blinded by Science” and “Blinded by Science reload” for deeper discussions on the studies that question the safety of Testosterone therapy.  I would say the questions about the safety of Testosterone therapy really should apply to the physicians knowledge or lack thereof and the practice of that knowledge.


Declining Testosterone levels is one thing, but what if there was evidence that sperm production was effected as well?  The other side of the coin could be found in the changes in sperm count and/or sperm concentration in men.  If there is evidence that sperm production is compromised as is Testosterone levels on the decline, then the conclusion that a more global Testicular dysfunction could be elicited.  What does the evidence show?  One in five men age 18 to 25 have abnormal sperm counts with 15-20% of young men with sperm counts < 20 million/ml.  How about some historical context?  A 1992 study found that the average sperm count of military men had dropped from 100,000 million/ml in 1940 to 60 million/ml at the time of the study.  Kind of gives credence to the argument that our grandfathers were better men.  Not only is this a near 50% decline in sperm count, but the definition of the low reference range of normal declined from 60 million/ml in 1940 to 20 million/ml at the time of the study.  Not only is the sperm count on the decline, according to this study, but the definition of “normal” is being redefined to make the abnormal normal.  A very alarming study from 2012 found that sperm count/sperm concentration from the general population of men was lower in recently studied men compared to that of men in infertile couples seeking treatment for infertility in 1940-1943.  In fact, the only level that recently evaluated men in the general population exceeded the sperm count/concentration of men in infertile couples from 1940-1943 was in counts less than 100 million/ml—particularly less than 60 million/ml.  The higher the sperm count, the more prevalent the infertile couples sperm count exceeded that of recent general population men—Ponder that for a moment.



Rolland M et al. Decline in semen concentration and morphology in a sample of 26 609 men close to general population between 1989 and 2005 in France. Human Reproduction. Dec 4, 2012.

As in Testosterone, the decline in sperm count is steady and not a precipitous collapse.  A 1995 New England Journal of Medicine study found a 2.1% annual decline in sperm count over a 20 year study.  A more recent 2012 study from Human Reproduction followed 26,609 French men from 1989 to 2005.   The authors concluded “there was a significant and continuous decrease in sperm concentration of 32.2%.  For a 35 year old man, this was equal to a sperm concentration decline from 73.6 million/ml in 1998 to 49.9 million/ml in 2005 (figure left).  Continued supporting evidence for a steady decline in sperm count/sperm concentration was found in a meta-analysis of 101 studies from 1934-1996 published in 2000.  The authors of this study found a 1.5% annual decline in American men and a 3% annual decline in European and Australian men.  Though there are studies that question a widespread decline in male fertility, the power of observation and the volume of evidence points to a worldwide decline.


Most attribute these declining numbers to men in industrialized and developed countries.  However, a 12 year study published in the Journal of Andrology of Tunisia men found a 29% decline in sperm count in Tunisia men.  This data points to a global problem, including developing countries, not just a problem confined to developed countries.


The data on declining Testosterone levels and the data on declining sperm counts and sperm concentrations provide compounded evidence of the growing problem in men—no pun intended.


To start, low Testosterone is the effect and not the cause.  I discuss these causes of low Testosterone in great detail in my first book “Man Boob Nation”.  A brief review of the causes of low Testosterone in men is warranted.  The primary causes of low Testosterone in men include:

  • Natural decline
  • Stress
  • Estrogen
  • Obesity
  • Inflammation
  • Toxins
  • Medications
  • Hormone Replacement Therapy (HRT)


These causes are far and away the primary causes of low Testosterone in men today.  The causes of low T are diverse and in that diversity, the expanded impact of low T is found.  Look to my book for a detailed discussion of the scientific data on these causes of low Testosterone in men.   I would like to add a few additions to this primary list:

  • Head trauma
  • Celiac disease
  • Vitamin D deficiency
  • autoimmune


The purpose of this post is not to discuss these new additions to the list of causes of low Testosterone in men, but know that the scientific literature points to these as contributors and causes of low Testosterone in men.  Look for me to discuss these in a later post.   Is low Testosterone as the effect the end point?  The answer is no.  The effect, that is low Testosterone, becomes the cause(s) of metabolic dysfunction that leads to Metabolic Syndrome.  To see the impact of low Testosterone as the cause of metabolic dysfunction, we must look at the metabolic implications of this dysfunction.  The metabolic implications of low Testosterone in men includes:

Why the concern about Metabolic Syndrome?  Metabolic Syndrome is the door way to disease.  Metabolic Syndrome is the door through which disease walks.  Metabolic Syndrome is not really a disease.  Metabolic Syndrome is a group of associations running together–remember the old adage ‘birds of a feather run together’?  Metabolic Syndrome is defined via 5 criteria:

  • abdominal circumference 
  • Triglycerides
  • glucose levels
  • blood pressure
  • HDL levels


Back to the starting quote referenced above:   “Androgen use and abuse is increasing in our society, either for therapeutic or recreational reasons”.


Medical providers must make sure that they use Testosterone for the former and not the latter—myself included.  If Testosterone therapy is only for ED, then Testosterone is simply for recreational purposes.  The recreational use of Testosterone is not just in the mere prescription use of Testosterone, but also the dose of Testosterone.  However, if low Testosterone has implications in metabolic dysfunction that leads to Metabolic Syndrome and disease beyond, then Testosterone therapy has significant therapeutic implications and is not simply for recreation.  As physicians, we shout evidence-based medicine from the mountain tops.  It is time we do more than talk the walk.  We have a responsibility to read the science, a responsibility to know the science, and a responsibility to practice the science.


To follow the timeline of low Testosterone to disease in men, there must be documented metabolic dysfunction that can be linked to low Testosterone.  This link needs to be more than just an association, but be involved in the cause(s) of the metabolic dysfunction.  These metabolic dysfunctions, as a result of low Testosterone, have metabolic implications in disease.  This blog post is the first in a series that will discuss 5 metabolic dysfunctions that result from low Testosterone and their associated metabolic implications in disease in men.  The 5 identified include:

  • Obesity
  • muscle loss
  • Inflammation
  • Insulin resistance
  • abnormal Cholesterol