Testosterone 101

What comes to mind when you hear talk of testosterone levels? If you're a sports fan, you may think of the latest athlete suspended for illegally raising his T level through anabolic steroids or other performance-enhancing drugs.

However, it's much more likely that your life will be affected by low testosterone levels. Decreases in these levels are a natural part of aging for many men. However, they can also affect younger, otherwise healthy males. But before we get into that, let's get a feel for what testosterone is and how it works.

What is Testosterone?

It's necessary to be aware of what exactly testosterone is before we can understand why healthy T levels are critical. This hormone belongs to a subdivision known as androgens or steroid hormones.

Androgens stimulate the growth of male characteristics. We can further categorize testosterone into the following three groups:

  • Albumin - Protein which binds to testosterone.
  • Sex hormone binding globulin (SHBG) - Protein created by the liver, binds to testosterone and carries it throughout the bloodstream.
  • Free testosterone - Nonprotein bound

These three subgroupings of testosterone are tested in two different ways. There is a comprehensive test which measures the levels of all three categories, and a test which only measures levels of free testosterone.

The hypothalamus and pituitary gland work together to control testosterone production and secretion. The hypothalamus signals to the pituitary gland to secrete follicle stimulating hormones and luteinizing hormones, which help to spark testosterone production.

There is a common misconception that testosterone is exclusively a male hormone. While it is much more dominant in men, women produce it as well. However, low T levels are only a problem for men.

Most of the testosterone in your body is produced by your sex organs, along with a small amount produced by your adrenal glands.

What Does Testosterone Do?

Testosterone and Puberty

As mentioned above, this hormone stimulates the growth of certain male biological characteristics. This hormone becomes especially important during the puberty stage.

Without healthy testosterone levels, the development from boyhood to manhood may be stunted. During puberty, testosterone produces the following changes:

  • Hair growth - Testosterone stimulates the growth of facial hair, body hair, and pubic hair
  • Genital growth - The penis and testes both become larger during puberty
  • Voice changes - During puberty, the voice begins to crack before deepening
  • Muscle & bone strengthening - Muscles and bones grow and become stronger
  • Growth spurts - There is a rapid increase in height during puberty
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    Sex drive - Sexual attraction and desire flourishes during puberty

This process usually takes 2-5 years, before a male develops from a boy to a biologically grown man.

Testosterone and Grown Men

Following puberty, testosterone is still essential to your health. For most men, T levels peak between ages 20 and 30 and gradually decline (for some men) around ages 30-35.

Your brain and pituitary gland work in tandem with your testes to produce testosterone and circulate the hormone through your bloodstream. The T level in your blood fluctuates throughout the day. Testosterone levels are highest during the morning and lowest at night.

There is a link between high T levels and certain behaviors, such as aggression and dominance. You can raise these levels by engaging in specific behaviors, such as competitive sports.

Similarly, frequent sexual activity can increase testosterone levels, while long periods of inactivity may cause them to drop.

About Testosterone Levels

Ranges of Testosterone Levels

Healthy testosterone levels fall into a relatively wide range. These levels are measured in nanograms per deciliter. Healthy total testosterone levels (the combined levels of albumin, SHBG, and free testosterone) range between 300 and 1000 ng/dl. Typical free testosterone levels are between 9 and 30 ng/dl.

testosterone levels

You must measure both total and free testosterone levels to get an accurate picture of this aspect of your health.

You could have healthy total testosterone levels and unhealthy free testosterone levels, or vice versa. It is important to promptly address the issue if either test reveals insufficient testosterone.

It’s also crucial to remember that healthy testosterone levels vary on an individual to individual basis. You and your neighbor could both have the same testosterone levels, but that doesn’t necessarily mean that both of your T levels are healthy. What’s healthy for you may be unhealthy for someone else.

Low Testosterone Levels & Their Symptoms

There are several symptoms of low testosterone levels. If you've been affected by multiple symptoms from the following list, you may want to get your levels checked:

  • Lack of sexual desire
  • Erectile dysfunction
  • Decreased sexual performance
  • Lack of energy
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    Mood swings
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    Severe depression
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    Anger issues
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    Reduction in physical strength and muscle mass
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    Decrease in physical endurance
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    Reduced cognitive function
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    Reduction in body hair
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    Skin alterations
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    Increase in abdominal fat
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    Reduced bone density

Although testosterone levels may occasionally drop as a natural byproduct of aging, they may also fall as a result of neurological issues.

The Aging Process and Lower Testosterone Levels

For many men, gradual decreases in testosterone levels are a natural component of the aging process. Beginning in your 40s, T levels start to drop by an average of 1.6 percent per year.

After a couple of decades, these levels drop to the point of hypogonadism - the diagnostic term for lack of testosterone production.

Lowered testosterone levels may be a natural byproduct of aging, but that doesn't diminish their adverse effects. The average American life expectancy has risen well over 60 years old. It's become increasingly important for older men to address low T problems if they want to live as healthily as possible in their golden years.

The Role of Testosterone

how testosteone affects males

The correlation between lower testosterone levels and sexual health problems may seem obvious, but testosterone plays an intricate role in several essential biological functions.

Sexual ​​​​Health

As we mentioned above, there are a variety of sexual symptoms for low testosterone levels. Such symptoms include; lowered libido, arousal, or erectile dysfunction. Many men discover their low T levels as a result of sexual dysfunction.

Body Fat and Muscle Mass

A research team at the Charles R. Drew University of Medicine and Science conducted a study on the correlation between testosterone levels and the ability to lose fat and build muscle.

They found that the participants with the highest testosterone levels had the lowest body fat levels and that lower testosterone levels correlated with higher body fat levels.

The muscle building aspect of this study had different results. The researchers discovered that T levels had no significant effect on the ability to build muscle mass unless those levels had artificially risen to an abnormal amount, comparable with that of steroid users.


Studies have also shown a correlation between lower T levels and a decreased ability for your body to fight off disease. Lower testosterone levels result in lowered insulin sensitivity, which increases the risk of developing type 2 diabetes.

Studies have also shown a heightened danger of developing heart disease and Alzheimer's disease.

Mental Health

The research on the effect of low testosterone levels on mental health is still inconclusive, but there have been a few studies that show a decline in cognitive function.

A study by Harvard Health showed that middle-aged men with higher testosterone levels also had better preservations of brain tissue. The same study showed that older men with high T levels performed better on cognitive tests.


There is a relationship between lower T levels and depression, although it's not quite clear yet what that relationship means. Depressed men have lower testosterone levels, but scientists aren't sure if the depression causes low T or vice versa.

However, men who have undergone testosterone treatments have reported a positive influence on their general mood.

Bone Health

Research has shown a direct relationship between testosterone levels and bone density. While it may be common knowledge that women suffer from decreased bone density as they age, these same issues affect men with low T.

Specifically, lower T levels result in a loss of bone mineral density. If left untreated, such weak bone structure puts men (especially older men) at a higher risk of developing osteoporosis. Studies have also shown that men who suffer from osteoporosis have lower testosterone levels.

Final Thoughts

Hopefully, you now understand how important a healthy testosterone level is to your overall wellbeing. Unfortunately, many men are unaware of the litany of health issues which can result from low T. It’s important that we work to raise awareness of this common issue.

For some men, there may be a stigma attached to these problems. Some of your male friends and family members may be embarrassed to talk about it, or see it as an indictment of their manhood. But in reality, there’s nothing to be embarrassed about. Low T affects men of all ages and backgrounds.

If you've experienced a multitude of the health problems discussed in this post, don't hesitate to get your levels tested. If you find that they're too low, testosterone therapy could help to treat a broad range of health problems, some of which you may not have even been aware of.

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