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Understanding How Testosterone Affects Men

Written by Author - Authors Medical experts of the National HRT Clinic - October 16, 2015


Testosterone is the most critical hormone for men. It is the primary “androgen,” or male hormone. Testosterone controls male physical features and most of the attributes of “maleness.”

In men and boys, testosterone plays several important roles, such as:

  • The development of the penis and testes
  • The deepening of the voice during puberty
  • The appearance of facial and pubic hair starting at puberty; later in life, it may play a role in balding
  • Muscle size and strength
  • Bone growth and strength
  • Sex drive (libido)
  • Sperm production

At all ages, for these reasons and more, testosterone is critical to a man’s quality of life.

Where Is Testosterone Produced?

Testosterone in men is made by the male sex organs, the testes. The hypothalamus and the pituitary gland are important in controlling the amount of testosterone produced by the testes. In response to the release of other hormones by the hypothalamus, the pituitary gland produces luteinizing hormone which travels in the bloodstream to the testes, which stimulates the production and release of testosterone.

Why Is Testosterone So Important to Men?

An adequate supply of testosterone is required for the development and maturity, physically, emotionally, and mentally, of boys to men. However, testosterone’s importance to men goes well beyond sexual maturity. Testosterone also plays a vital role in:

  • The building of muscle and bone
  • Helping to metabolize fat
  • Regulating sleep
  • Improving mood
  • Improving cognitive abilities

In addition, testosterone is essential to having a happy and healthy sex life. Testosterone has also been linked to maintaining a healthy heart and lowering your risk of developing cardiovascular disease.

Testosterone is the most critical hormone to a man’s health, vitality, and wellness.

How Does Testosterone Impact the Reproductive System?

Testosterone impacts a man’s ability to father a child. Testosterone is required for sperm production, but it is other hormones, and not testosterone, that stimulate the production of sperm. Men who may be having fertility issues, could be suffering from low testosterone. Male infertility can have many causes, not all of which are related to sperm count. Other issues can also influence a man’s ability to conceive a child, such as:

  • Libido or sex drive
  • Erectile dysfunction (ED)
  • Sperm motility, or their ability to swim

Testosterone levels are related to all the above. Men with low testosterone may have decreased sperm count, weak or less motile sperm, and low libido, as well as ED. Low testosterone may not directly cause infertility. But it can lower sperm count, and negatively impact your ability to father a child in several ways.

How Does Testosterone Impact a Man’s Psycho-Emotional Well Being?

Testosterone also has a significant influence on a man’s emotional states. Testosterone has been shown to play an important role in supporting cognitive abilities and a man’s ability to focus on organizational tasks. In addition, less than normal testosterone levels can trigger any number of negative emotional states. Low testosterone has been associated with:

  • Increased irritability
  • Mood swings
  • Increased anxiety and depression
  • Increased levels of stress

Most of testosterone’s impact on cognition and emotional states is related to the fact that it is a necessary precursor to critical “brain chemicals,” known as neurotransmitters. Two of the most important of these “feel good chemicals” are dopamine and serotonin, both of which rely on testosterone for their production.

What Happens to Testosterone Levels as Men Age?

Despite its vital importance, testosterone levels decrease as you age. Testosterone levels peak when you are in your 20s. By the time a man is over 30, testosterone levels can drop by as much as 1 to 2 percent per year. That drop adds up over time, and can lead to the symptoms of low testosterone. Low testosterone is sometime referred to as “Low-T” or “andropause” in men.

What Are the Normal Testosterone Levels for Men?

Normal levels of testosterone vary by age and are expressed in a range. Testosterone levels are measured in nanograms per deciliter (ng/dl).

Age Average Male Total Testosterone ng/dL
6 Months – 9 Years 7-20
10-11 7-130
12-13 7-800
14 7-1,200
15-16 100-1,200
17-18 300-1,200
19+ 240-950
40-49 252-916
50-59 215-878

How Do I know If I Have Low Testosterone?

If you are a man between the ages of 40 and 65, it is very likely that you have some degree of low testosterone. According to the American Urological Association, about 2 out of 10 men older than 60 years have low testosterone. That increases slightly to 3 out of 10 men in their 70s and 80s. While testosterone levels drop in all men as they age, age alone is not a determining factor whether you do, or do not have Low T. Some men tolerate the yearly drop in testosterone well. Others feel it more, and exhibit the signs and symptoms of low testosterone.

Testosterone levels decline as a man ages, leading to age-related testosterone deficiency, or “low testosterone.”

What Are the Signs of Low Testosterone?

Here are 10 of the most common signs of low testosterone in men.

  • Low sex drive – Testosterone plays a key role in sex drive or libido in men. When men experience a decline in interest in sex, or ability to perform sexually, low testosterone is usually to blame
  • Difficulty getting or maintaining an erection – Testosterone also plays a critical role in getting and maintaining an erection. Erectile dysfunction (ED) is often a sign of low testosterone.
  • Low semen volume – Testosterone also has an important role in the production of semen. Men with low T, if they can maintain an erection till orgasm, will often notice a decrease in the volume of their semen during ejaculation.
  • Fatigue – Tiredness or lack of energy is another symptom of low testosterone. This can occur for several reasons. Low T can interfere with normal sleep patterns, resulting in daytime fatigue. It also decreases your metabolism, or your ability to produce energy on a cellular level.
  • Loss of muscle mass – Testosterone, along with another critical hormone — human growth hormone (HGH), is essential to build muscle. Men with low testosterone find it hard to build lean muscle, even when working out.
  • Increased body fat – Low T lowers metabolism, leading to increased fat and weight gain — particularly belly fat.
  • Decreased bone mass – Loss of bone density, or osteoporosis is a condition usually associated with women. But men can suffer from age-related bone loss as well. In men, such bone loss is usually related to low testosterone.
  • Mood changes – As mentioned above, low testosterone also impacts moods and a man’s emotional states.
  • Affected memory – Memory loss, lack of focus, and difficulty with cognitive tasks, is another sign of low testosterone.
  • Smaller testicle size – Low testosterone can contribute to smaller-than-average sized testicles and or penis size.

Testosterone Replacement Therapy for Men

If you are between the ages of 40 and 65 and are experiencing any or all of the symptoms mentioned above, you could be suffering from low testosterone. However, the only way to know for sure is to have your testosterone levels checked.

A simple blood test is all that is required to check your testosterone level. If you are found to have below the normal level of testosterone for your age, you may be prescribed testosterone replacement therapy, Testosterone therapy can only be legally obtained with a doctor’s prescription.

Testosterone therapy is available in several forms — from gels and patches, to injections. Our doctors have found that testosterone injections are the safest and most effective form of testosterone therapy.

The benefits of testosterone therapy for men with low testosterone are many. One of the first benefits of testosterone therapy that men notice is an improvement in their sex lives. In addition to increasing the libido, testosterone therapy can also:

  • Improve heart health
  • Improve memory and cognition
  • Prevent osteoporosis by improving bone density
  • Increase your ability to burn fat, leading to weight loss
  • Increase your ability to build lean muscle and increase muscle strength
  • Improve mood
  • Improve sleep

Any medical doctor can write you a prescription for testosterone replacement therapy. But that does not mean you want to go to just any doctor for your testosterone injections.

You want to go to a doctor or clinic that specializes in age-related hormone decline in men. At our testosterone clinics, we take an individualized approach to your symptoms, and prescribe the best course of testosterone therapy for your unique needs and lifestyle.

Furthermore, we take a holistic approach to your healthcare, and will provide you with other services as needed. These can include: diet and nutritional counseling, exercise and lifestyle changes, as well as other hormone replacement therapies as needed such as growth hormone therapy.

Testosterone replacement therapy is the best way to treat low testosterone in men.

Now that you understand a little bit more about just how important testosterone is to men, why not contact us today, and find out your own testosterone level, and see if you are a candidate for the many life-changing benefits of testosterone replacement therapy.

Medically reviewed by   Reviewers National HRT Staff - Updated on December 4, 2020

Please note that the information provided in this article is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.