Testosterone is the main male sex hormone and regulates bone density, muscle mass, fertility, fat distribution, and red blood cells production. When levels of testosterone drop below levels that are healthy, they can lead to conditions like hypogonadism or infertility.
Low testosterone is becoming more and more common. The number of prescriptions for testosterone supplements has increased 5-fold since 2012 (1). This increase might be a result of increased hormonal disruptors in the environment, increased rates of obesity and insulin resistance, drug use, as well as past use of prohormones and illegal anabolic steroids. Testosterone is the hormone responsible for the development of male sexual characteristics.
Females also produce testosterone, usually in smaller amounts. It is a type of androgen produced primarily by the testicles in cells called the Leydig cells. In men, testosterone is thought to regulate several functions alongside sperm production including libido, bone mass, fat distribution, muscle size and strength, and red blood cell production.
- sex drive
- bone mass
- fat distribution
- muscle size and strength
- red blood cell production
The brain and pituitary gland control testosterone levels. Without adequate amounts of testosterone, men become infertile. This is because testosterone assists the development of mature sperm.
Testosterone decreases naturally with age. It is important to receive tests to determine whether any imbalances are due to an active condition. When a man has low testosterone or hypogonadism, he may experience:
- Rduced sex drive
- Erectile dysfunction
- Low sperm count
- Enlarged or swollen breast tissue
Over time, these symptoms may develop in the following ways:
- Loss of body hair
- Loss of muscle bulk
- Loss of strength
- Increased body fat
Chronic, or ongoing, low testosterone may lead to osteoporosis, mood swings, reduced energy,
and testicular atrophy. Testosterone imbalances can be detected with a blood test and treated
Testosterone levels and aging
The effects of gradually lowering testosterone levels as men age have received increasing attention in recent years. It is known as late-onset hypogonadism. After the age of 40, the concentration of circulating testosterone falls by about 1.6 percent per year (2) for most men. By the age of 60, the low levels of testosterone would lead to a diagnosis of hypogonadism in younger men. About 4 in 10 men have hypogonadism by the time they reach 45 years old. The number of cases in which older men have been diagnosed as having low testosterone increased 170% since 2012. Low testosterone has been associated with increased mortality in male veterans. Late-onset hypogonadism has become a recognized medical condition, although many of the symptoms are associated with normal aging.
Symptoms of late-onset hypogonadism (3):
- Diminished erectile quality, particularly at night
- Decreased libido
- Mood changes
- Reduced cognitive function
- Fatigue, depression, and anger
- A decrease in muscle mass and strength
- Decreased body hair
- Skin changes
- Decreased bone mass and bone mineral density
- Increase in abdominal fat mass
As well as sexual dysfunction, late-onset hypogonadism has also been associated with metabolic disease and cardiovascular disease. The degree to which testosterone levels decline varies between men, but a growing number of men experience the effects of reduced testosterone levels. Life expectancy has increased, and many men now live beyond the age of 60 years. As a result, a higher number of men see the
effects of age-related testosterone depletion.
Testosterone replacement therapy
Testosterone replacement therapy (TRT) can help restore some affected functions of low testosterone.
The treatment can be administered by:
- skin gels and patches
- tablets that are absorbed through the gums
These can, however, trigger side effects, including:
- increased red blood cell count
- prostate and breast enlargement
- in rare cases, breathing difficulties during sleep
- increased risk of cardiovascular disease, although this is subject to debate
Deciding to pursue a course of TRT involves deciding between the perceived benefit of the therapy on the symptoms of a particular individual and the risks of the treatment. A recent study, for example, suggests that TRT provides a reduced risk of overall mortality and stroke for men whose testosterone levels have normalized with TRT. Current research is conflicting. Additional studies into testosterone replacement are necessary for physicians to fully understand its potential risks and benefits, and to identify the individuals that may see the most benefit.
For men, testosterone levels are important to maintain, but they naturally decrease over time. It’s important to see a physician who specializes in TRT/HRT. Much of the conflicting studies can
be attributed to the treatment by physicians who are not knowledgeable about TRT/HRT.
1. J. Abram McBride, Culley C. Carson, III, and Robert M. Coward Testosterone deficiency in
the aging male Therapeutic Advances in Urology 2016 Feb; 8(1): 47-60.
2. Akira Tsujimura The Relationship between Testosterone Deficiency and Men's Health World
J Mens Health. 2013 Aug; 31(2): 126-135.
3. Marielle H. Emmelot-Vonk, MD; Harald J. J. Verhaar, MD, PhD; Hamid R. Nakhai Pour,
MD, PhD; et al Effect of Testosterone Supplementation on Functional Mobility, Cognition, and
Other Parameters in Older Men A Randomized Controlled Trial JAMA. 2008;299(1):39-52.
4. Rishi Sharma, Olurinde A. Oni , Kamal Gupta, Guoqing Chen , Mukut Sharma , Buddhadeb
Dawn, Ram Sharma, Deepak Parashara, Virginia J. Savin, John A. Ambrose, Rajat S. Barua
Normalization of testosterone level is associated with reduced incidence of myocardial infarction
and mortality in men European Heart Journal, Volume 36, Issue 40, 21 October 2015, Pages 2706-2715.