Testosterone Facts: Overview Of Testosterone’s Function, Conditions and Treatments

Testosterone Facts: Overview Of Testosterone's Function, Conditions and Treatments


is the primary male hormone, overseeing physiological processes like muscle growth, reproduction, fat distribution, and bone mass. Men having low levels of testosterone can experience a wide variety of adverse conditions, including bone loss, infertility, and depression.

Increasingly, the number of men experiencing low-t is rising at an alarming rate. As a result, the availability of testosterone-boosting products, both natural and prescription-based, has increased by a whopping 500% in just the last few years.

Fortunately, there are ways for men who experience low testosterone to increase their levels. This article will attempt to give an overview of testosterone and it’s function in the body, and address whether or not men should be concerned about a decrease in this hormone as they age.

What is Testosterone?

Testosterone Facts: Overview Of Testosterone's Function, Conditions and Treatments

Testosterone is the primary androgen, or male hormone. It facilitates normal male development such as muscle growth, facial hair, and a deep voice. A hormone is a signaling chemical in the body that regulates physiological and behavioral changes.

Specifically, testosterone is the male sex hormone which causes the development of masculine characteristics.

Testosterone in men is created by Leydig cells, which are located in the testicles. Because it regulates the development of sperm cells, insufficient production of testosterone can lead to male infertility.

The amount of testosterone produced is regulated by the brain and pituitary gland. As soon as it’s created, it enters the bloodstream in order to perform it’s different responsibilities.

This powerful hormone is tied to many important functions in the male body, including:

  • Muscle mass and strength
  • Sex drive
  • Distribution of fat
  • Bone mass
  • Sperm production
  • Production of red blood cells

Even though it’s classified as a male sex hormone, testosterone¬† is also found in women, but in much smaller amounts. In the female body, healthy levels of the hormone assist with muscular strength, bone mass, and libido – but excess amounts can lead to fertility issues and male pattern baldness (see hypergonadism, below).

Testosterone-Related Medical Conditions

Testosterone Facts: Overview Of Testosterone's Function, Conditions and Treatments

Testosterone-related conditions are generally caused by hormonal imbalance and fall into two categories: low testosterone (or hypogonadism) and high levels of testosterone (or hypergonadism). Having either low or high T-levels can lead to a number of unpleasant side-effects and physiological dysfunctions where the hormone plays an active role.

Symptoms of Low Testosterone in Men

Some general symptoms of low testosterone production in men include:

  • Lowered sex drive
  • Erectile dysfunction
  • Depression and/or lack of motivation
  • Mental fog
  • Gynecomastia
  • Low sperm count/infertility
  • Loss of muscle mass
  • Reduced strength and stamina
  • Difficulty sleeping
  • Increase in body fat
  • Loss of body hair

Eventually, chronic hypogonadism can also lead to other symptoms, like bone loss, moodiness, persistent fatigue, and testicular atrophy.

Causes of Hypogonadism

There are many potential causes for low testosterone in men, including:

  • Aging (see below)
  • Medical conditions affecting hormone production
  • Injury to, or infection of the testicles
  • Certain prescription medicines, like opioids (Opioid Induced Androgen Deficiency)
  • The use of anabolic steroids
  • Long-term conditions, like obesity, diabetes, liver disease, and kidney disease.
  • Genetic/congenital disorders, like hemochromatosis, myotonic dystrophy, Prader-Willi syndrome, Turner syndrome, CHARGE syndrome, Kallman syndrome, and Klinefelter syndrome.


Conversely, excess production of testosterone is a much rarer condition that can trigger early pubescence, even in boys younger than 9 years old. High levels of testosterone can also negatively impact women, causing a wide variety of symptoms:

  • Male pattern baldness
  • Deep voice
  • Enlarged clitoris
  • Acne and oily skin
  • Increased risk of uterine fibroids
  • Menstrual irregularities
  • Reduced breast size
  • Facial hair

It’s important to get testing done to determine if any irregularities are due to aging, or a more serious medical condition. Any imbalances can be easily detected with a simple blood test, followed by an appropriate treatment.

The Effects of Aging on Testosterone Levels

Testosterone Production by Age

The natural decrease in testosterone production that occurs with age, commonly called andropause, or late-onset hypogonadism (LOH), is now part of the mainstream of public awareness. According to the National Health Institutes, the amount of a man’s free testosterone decreases by 1.6% per year past the age of 40.

At this rate, a 60-year old man’s low t-levels can be essentially considered hypogonadic. By the age of 45, around 40% of men will suffer from low testosterone.

Shockingly, there has been a 170% increase in cases of reported hypogonadism in older men just since 2012. Even though many of the same symptoms are often attributed to the aging process, late-onset hypogonadism is now identified as a bonafide medical condition.

Causes of Age-Related Decrease in Testosterone

What causes a decrease in testosterone production with age? Generally speaking, it’s due to a diminished function of the hypothalamus and pituitary gland, as well as reduced testosterone output by the testicles. [Source]

Another cause is a high level of Sex Hormone-Binding Globulin, or SHBG. Along with other sex hormones, SHBG binds to testosterone, basically neutralizing it’s effects. Testosterone that is not bound by SHBG is referred to as “free” testosterone, meaning it’s readily available in the bloodstream to implement it’s effects on the body.

At any given time, the vast majority of total testosterone in the body is bound by SHBG, somewhere around 98%. However, with aging, the levels of SHBG often begin to rise, causing an even greater reduction in the levels of available testosterone. [Source]

Symptoms of Late-Onset Hypogonadism (Andropause)

The various signs of late-onset hypogonadism/andropause can include:

  • Inability to achieve or maintain an erection
  • Loss of sex drive
  • Diminished brain function
  • Fatigue, depression, mood swings
  • Increase of belly fat
  • Diminished muscle tone and strength
  • Reduction in body hair
  • Thinner, less elastic skin
  • Reduced bone density

Besides these symptoms, andropause has also been linked to cardiovascular and metabolic diseases, and even an increase in mortality. The extent to which testosterone reduction occurs in older men can vary, but the number of those dealing with the condition is only increasing.

Since more men are now living longer, more will likely experience the negative effects associated with andropause.

Treatment Options

Testosterone Facts: Overview Of Testosterone's Function, Conditions and Treatments

Today, there are several options for treating conditions related to testosterone production. However, the methods of treatment for andropause will usually be approached differently than with those of true hypogonadism.

Testosterone Replacement Therapy (TRT)

Testosterone replacement therapy (TRT) can be an useful way to treat the effects of low testosterone. Research indicates that TRT is effective at increasing red blood cells and improving bone density, but has little impact on cognitive function.

It has also been shown to possibly increase life expectancy and decrease the risk for stroke. Testosterone Replacement Therapy is only available by prescription from a licensed professional.

There are three primary methods for administering TRT treatment: Intramuscular injections, transdermal gels or patches, and sublingual tablets.

TRT Side Effects

Treatment with TRT has several potential negative side effects, such as:

  • A potential increased risk for cardiovascular disease
  • Gynecomastia
  • Enlarged prostate
  • Acne
  • Excessive red blood cell production (polycythemia)
  • Potential for sleep apnea

Perhaps the most surprising consequence associated with long-term testosterone replacement therapy is the cessation of natural testosterone production. Once testosterone is introduced into the body through artificial means, the hypothalamus, pituitary, and testicles (which begin to shrink in size following treatment) cease regulating the production of testosterone altogether.

Furthermore, the longer the TRT treatments continue, the more difficult it becomes for the body to resume it’s natural production of testosterone. For these reasons, when choosing testosterone replacement therapy it’s important to weigh any likely benefits against the potential risks.

More research is needed in order to form a more complete picture of the full effects, as the current evidence is not conclusive and often contradictory.

Testosterone Prescription Pills

Another form of treatment for hypogonadism is oral testosterone medication (the primary form being testosterone undecanoate), which includes brands such as Nebido, Aveed, and Andriol. Currently, there are no oral testosterone drugs available in the United States that have been FDA-approved.

Research examining the efficacy of prescription testosterone pills in older men indicates little to no adverse side effects, while also increasing lean muscle mass and fat loss. However, no changes were noted in bone mass, mental acuity, or functional mobility. [Source]

The FDA has stated that prescription testosterone pills are not recommended for the treatment of andropause/LOH. Since there is need for further research in order to fully evaluate it’s effectiveness, older men should only seek this type of treatment in the more extreme cases of low-t.

Testosterone-Boosting Supplements

Testosterone Facts: Overview Of Testosterone's Function, Conditions and Treatments

Testosterone-boosting supplements are a safer alternative to TRT and illegal steroids. Rather than artificially introducing testosterone into the body, these supplements encourage the natural increase of free testosterone levels.

Normally, these supplements work by preventing SHBG from binding to testosterone, thereby freeing up the hormone where it would have otherwise been rendered inactive. Though the results from using these types of supplements aren’t as dramatic as with TRT, they can still provide a fair level of effectiveness, without the negative consequences associated with injections and steroid use.

Some common ingredients found in testosterone boosters include:

Most popular testosterone supplements will incorporate some combination of these and other ingredients, although each individual component can be taken separately as well.

Some of the more reputable brands include:

See Also: The Best Testosterone Boosters of 2024


Testosterone-boosting supplements should not be confused with prohormones, which are essentially a type of steroid. Instead of introducing testosterone directly, as with injections, prohormones are converted into testosterone once in the body.

Also called “designer steroids,” prohormones are typically less effective than steroids, yet more dangerous and with a greater risk for harmful side effects. For this reason the United States Congress passed the Anabolic Steroid Control Act of 2004, effectively banning many of the chemical precursors used in the manufacture of prohormone supplements.


Maintaining healthy testosterone levels is important for men,¬† but these levels will likely diminish with age. If you are experiencing symptoms that may indicate hypgonadism that’s not age-related, it’s important to see a doctor since it may indicate an active condition that needs to be addressed.

Medical treatment can be inconvenient and expensive, with unpleasant side-effects – therefore careful consideration should be given before deciding on an option like TRT. Very often, natural testosterone-boosting supplements give excellent results, without the risks associated with steroid use.

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