How does Testosterone Affect Bone Growth?

by Benjamin Bunting BA(Hons) PGCert

 ben bunting BA(Hons) PgCert Sport & Exercise Nutriton  Written by Ben Bunting: BA(Hons), PGCert. Sport & Exercise Nutrition. L2 Strength & Conditioning Coach.

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Have you ever wondered what chemical processes going around in various tissues of your body?

In this article we shall answer that questions and cover the following points:

  • What are hormones?
  • What is testosterone?
  • Testosterone's functions in men
  • Testosterone's function in women
  • Bone health
  • Testosterone deficiency and bone problems
  • How to naturally raise testosterone
  • Conclusion

Many of us are unaware of the importance of hormones in our bodies. The truth is that they are everywhere. I mean everywhere. If you feel like sleeping, there is probably a hormone that is working towards that goal.

If your goal is to hit a personal record (PR) of squatting 100 kilos, there are some hormones helping you out.

Similarly, bone growth and overall growth require adequate hormone supply and hormonal balance.

While many people know that growth hormone is required for bone growth, testosterone is also essential. 1

What are hormones?

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Hormones are chemical molecules that are produced by the body.

Due to the fact that they are produced in the body, they are also called endogenous compounds or substances act by binding to receptors present at specific sites in our body to perform their functions.

They are needed by humans in very precise quantities in order to live a healthy balanced life.

Regulating processes such as metabolism, growth and development, mental maturation, and mood; hormones are proven to be much more important than they seem.1

Hormones in our body include cortisol, growth hormone, insulin, catecholamines, thyroid hormone, testosterone, and many more, with each having some general and some specific functions.

Their importance can be seen when an imbalance in the amount of a particular hormone occurs due to suppressed or excess secretion of that hormone leading to health issues.

For example, an excess of thyroid can cause increased metabolism and insomnia. On the other hand, its lack of secretion may induce somnolence (excessive sleepiness) and decreased metabolism. 2 

The textbook role of testosterone known by most people is either sexual function or reproduction.

It is given no regard in regulating other functions in the body. Surprisingly, current studies have found an increasing role of testosterone in many metabolic processes of the body.

In this article, we will be discussing the effects of testosterone in the body particularly on bones. 

What is testosterone?

how does testosterone affect bone growth?

Testosterone, contrary to the normal belief, is found in both males and females and has functions in both genders as well.

It is a steroid hormone that is produced in the testis of males, the adrenal glands, and the ovaries of females, but in only a small amount.

Steroid hormones are derived from cholesterol and are fats in nature. Testosterone is considered responsible for the physical characteristics of a normal male including growth, muscle mass, and sexual maturity.3

We will also discuss some of its implications for the female body shortly. So, stay tuned!

Testosterone timeline

From adolescence to adulthood your testosterone levels will fluctuate with age. Testosterone has many key regulatory functions in the body such as an increase in muscle mass, fat distribution, red blood cell production, bone regulation, and a couple more.

These effects are dose-dependent. What it means is that, the more testosterone a person has, female or male, the more male-like or masculine features they have. Intuitively, the male-like features are less prominent in females. 

Interestingly, testosterone is not just necessary for adults. Its role is documented throughout the pregnancy.

For example, during embryogenesis, testosterone is required by a male baby for normal growth of its genitalia and the suppression of female genitalia.

A testosterone deficiency (hypogondasim), hence, can lead to abnormal development of male genitalia, infertility, and so on.

Testosterone secreting glands

Regarding production, testosterone is synthesized in our bodies at various locations.

In males, it is mainly formed in the Leydig cells of the testis, while in females its production occurs in the ovaries.

A small amount is also made in the innermost zone of the adrenal cortex, Zona Reticularis(ZR), of both sexes. The adrenal cortex, or ZR, is also responsible for the production of androgens.

Androgens, as you might know, are testosterone-like hormones with similar functions.

They are mainly responsible for pubic and axillary (armpit) hair growth. As a side note, in some disease conditions, like polycystic ovarian syndrome (PCOS), the androgen production is abnormally raised.4  

Testosterone production is closely related to two other hormones that are present in the body.

These are follicle-stimulating hormone (FSH) and luteinizing hormone(LH). FSH and LH are called gonadotropins (hormones stimulating the testes) produced and released from the pituitary gland.

A small, pea-sized gland in the brain, is also called the master gland of the body. The pituitary gland is, in turn, controlled by the hypothalamus.

Hypothalamus is simply the mastermind behind hormonal balance. The smallest harm to this intricate structure and you might lose all your testosterone.5  

Testosterone levels for men and women

On excretion, testosterone circulates in the blood to reach the sites mentioned before and results in the production of testosterone.

Peaking at about 20 years of age, testosterone levels in men may vary from 270-1070 ng/dL while in women it may be in the range of 15-70 ng/dL.

Levels fluctuating above or below this normal range are considered by many to be out of balance.

In most men, testosterone levels start to decline as age increases and it sometimes requires hormone replacement therapy.6,7 

The function of testosterone in males 

In men, testosterone is the primary androgen (male sex hormone) secreted throughout life by the testes.

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Effects

Its production increases significantly during puberty and brings about a number of changes such as those mentioned above as well as sperm production, growth of hair on the face, back, and pubic regions, while also deepening the voice and thickening the skin.3 

Testosterone is also highly associated with sex drive (libido) and a lack of testosterone may result in poor sexual performance and reduced sexuality. Other effects include erythropoiesis.

Erythropoiesis is the main cause of an increase in red blood cell production observed post-puberty. An increase of red blood cell production can help with improving endurance.

Furthermore, the appearance of bald patches on the head which occurs in people having the gene for male bald patterns, and an increase in the metabolic activity of cells are also considered effects of testosterone.  

In addition, there is an increase in metabolism (energy expenditure). This is possibly an indirect result of testosterone on protein anabolism. Increased muscle protein synthesis is by far the most commonly sought-after effect of testosterone.

In simple terms, it means developing huge muscles (hypertrophy). The large traps, biceps, quads, and abs that every man dreams of.

Lastly, a profound effect of testosterone that is visible post-puberty is the excessive secretion of sebaceous glands of the face resulting in acne.

Acne, therefore, is one of the commonest features of male adolescence.3,8  

The function of testosterone in females

Being one of the several androgens in females, testosterone has important effects despite their lower production such as bone density and strength, normal ovarian function, and sex drive.

Its importance in maintaining normal ovarian function is seen when women of child-bearing age have difficulty in getting pregnant as a result of increased testosterone levels in conditions such as Polycystic Ovarian Syndrome (PCOS).

Testosterone also increases muscle mass in women but this increase is credited more to estrogen which is the primary sex hormone in females.

It also plays a role in the thickening of the hair in women as is seen when androgen deficient females are treated with testosterone.9 

Testosterone and Bone Health 

how does testosterone affect bone growth?

Coming to the main topic; testosterone and its effects on the bone.

Bone formation is a complex mechanism that is primarily regulated by hormones.

Apart from hormones, external stimuli like exercise can also affect bone growth. The main hormones that play a role in bone growth and regulation are growth hormone, parathyroid hormone, testosterone, thyroid hormone, and estrogen. 10

In this list, testosterone and estrogen have different roles. Let's take estrogen first.

It makes the bone grow linearly (increases the length). It also stimulates the completion of bone growth. This is the reason why females have growth spurt earlier than males, but their overall height is reduced. 

Testosterone on the other hand is necessary for bone growth and reduced bone resorption. This happens via three mechanisms. 11 

1. Firstly, testosterone stimulates the differentiation of osteoblasts.

Osteoblasts are cells that produce the bone. You can think of these cells as constructors forming the framework of a pillar.

Today, studies have found that osteoblasts contain androgen (testosterone) receptors that stimulate their growth and survival, promoting bone growth.  

2. Secondly, testosterone reduces the formation of osteoclasts.

The osteoclasts are cells that carry out bone resorption. In other words, they chop down the bone to provide calcium and other minerals.

Science has postulated that testosterone is converted to estrogen in the bones which inhibits the osteoclasts formation.

Overall, it decreases bone breakdown. In fact, an androgen receptor deficiency or testosterone deficiency leads to an increase in the number of osteoclasts. 

3. Lastly, testosterone promotes the production and longevity of osteocytes.

Osteocytes are cells that improve bone mineralization. They make your bone thicker and stronger.

As mentioned earlier, testosterone conversion into estrogen in the bones stimulate the survival of osteocytes.

This in turn leads to increase bone mineralization and greater bone strength. Alas, adequate amounts of testosterone are necessary for bone health.

Testosterone will also push your bones to be stronger, especially if you work out regularly and put stress on your bones.11 

Testosterone Deficiency and Bone problems

Unfortunately, many men suffer from testosterone deficiency.

Typical male testosterone levels

A study has shown that every 1 in 4 men suffers from low testosterone levels.11

Normal ranges for testosterone levels are 320 -300 ng/dL with 300ng/dL being the cutoff value, values lower than 280 ng/dL are considered low levels of testosterone in males.7,12

How does testosterone affect bone density?

A testosterone deficiency can lead to effects opposite to what we described above.

Bone growth is reduced and bone resorption is increased. Moreover, the bone becomes less heavy due to reduced mineralization. 

Low testosterone levels can cause skeletal problems that involve a weakening of the bones and fractures.

Research done by the US cohort of the Osteoporotic Fractures in Men Study and the Dubbo Osteoporosis Epidemiology Study showed positive correlations between the decrease in bone density mineral (BDM) and low levels of serum testosterone12.

Bone diseases

Such a decrease in bone density minerals can cause an increased risk of weakening the bones leading to osteoporosis and osteopenia. 

Testosterone deficiency may even cause the development of rheumatoid arthritis.

This autoimmune disease causes the body to attack its own cells resulting in tissue inflammation and joint pain.  

Luckily, testosterone replacement therapy (TRT) has proven to help with the loss of bone mass and enhance BDM, however, TRT isn't without risk.

Testosterone therapy for reversing osteoporosis has also been recommended by the endocrine society in their 2012 ‚Äėosteoporosis in men guidelines‚Äô.

TRT can help alleviate joint pains by assisting in releasing endorphins causing an analgesic effect.13

While it can be painful and debilitating, testosterone deficiency can be cured by adequate medical care. 12

Visit your healthcare provider today if you feel like your testosterone levels are fallen low. 

How to Naturally Raise your Testosterone Levels 

Naturally, you can induce your testosterone production in several ways. Some common examples are:

  • Exercising regularly, especially weight training
  • Eating a balanced diet containing protein, omega-3 fatty acids, fibers
  • Enjoy adequate sleep
  • Leave a stressful lifestyle
  • Spend more time doing what you like
  • Having a good sexual life
  • Use a natural supplement with clincially proven ingredients

Conclusion

In conclusion, testosterone is a vital hormone for everyone. Testosterone plays an important role in reproduction, hair growth, and maintaining bone density in the body.

A testosterone deficiency may lead to reduce sexual drive, loss of muscle mass, obesity, and bone weakness.

For people who currently suffer from osteoporosis, rheumatoid arthritis, or any other condition associated with low testosterone levels, elevating testosterone levels is proven to be a beneficial solution to alleviate their symptoms and pain. 

Having a good hormonal health is imperative for a healthy body and mind.

Hormones are frequently neglected by people and their imbalance can leave people with serious consequence.

Fortunately, every problem has a likely solution.

If you are feeling any symptoms of testosterone deficiency or other weaknesses, consult your physician or healthcare provider and get your hormones checked.

Getting your hormones in balance will save you from tons of issues. 

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References:

  1. Campbell M, Jialal I. Physiology, Endocrine Hormones. StatPearls. Published online October 1, 2021. Accessed May 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK538498/
  2. Shahid MA, Ashraf MA, Sharma S. Physiology, Thyroid Hormone. StatPearls. Published online May 8, 2022. Accessed May 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK500006/
  3. Nassar GN, Leslie SW. Physiology, Testosterone. StatPearls. Published online January 4, 2022. Accessed May 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK526128/
  4. Dutt M, Wehrle CJ, Jialal I. Physiology, Adrenal Gland. StatPearls. Published online May 8, 2022. Accessed May 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK537260/
  5. Shimon I, Lubina A, Gorfine M, Ilany J. Feedback inhibition of gonadotropins by testosterone in men with hypogonadotropic hypogonadism: Comparison to the intact pituitary-testicular axis in primary hypogonadism. Journal of Andrology. 2006;27(3):358-364. doi:10.2164/jandrol.05140
  6. Halpern JA, Brannigan RE. Testosterone Deficiency. JAMA. 2019;322(11):1116-1116. doi:10.1001/JAMA.2019.9290
  7. Rivas AM, Mulkey Z, Lado-Abeal J, Yarbrough S. Diagnosing and managing low serum testosterone. Proc (Bayl Univ Med Cent). 2014;27(4):321. doi:10.1080/08998280.2014.11929145
  8. Breehl L, Caban O. Physiology, Puberty. StatPearls. Published online April 5, 2022. Accessed May 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK534827/
  9. Glaser RL, Dimitrakakis C, Messenger AG. Improvement in scalp hair growth in androgen-deficient women treated with testosterone: a questionnaire study. The British Journal of Dermatology. 2012;166(2):274. doi:10.1111/J.1365-2133.2011.10655.X
  10. Sayed SA el, Nezwek TA, Varacallo M. Physiology, Bone. StatPearls. Published online October 9, 2021. Accessed May 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK441968/
  11. Mohamad NV, Soelaiman IN, Chin KY. A concise review of testosterone and bone health. Clinical Interventions in Aging. 2016;11:1317. doi:10.2147/CIA.S115472
  12. Golds G, Houdek D, Arnason T. Male Hypogonadism and Osteoporosis: The Effects, Clinical Consequences, and Treatment of Testosterone Deficiency in Bone Health. International Journal of Endocrinology. 2017;2017. doi:10.1155/2017/4602129
  13. Jo DG, Lee HS, Joo YM, Seo JT. Effect of Testosterone Replacement Therapy on Bone Mineral Density in Patients with Klinefelter Syndrome. Yonsei Medical Journal. 2013;54(6):1331. doi:10.3349/YMJ.2013.54.6.1331