What Does Testosterone Serve ?: Function in Man and Woman, Causes and Consequences of the Imbalance of this Hormone and Much More

It is the crucial male sex hormone that regulates fertility, muscle mass, fat distribution, and the production of red blood cells.

When testosterone levels fall below healthy levels, they can lead to conditions such as hypogonadism or infertility.

However, there are sources from which people with low testosterone levels can increase their levels.

Low testosterone is increasingly common. The number of testosterone supplement recipes has quintupled since 2012.

The researchers discovered that the complex effects of testosterone depend in part on how the body converts to a type of estrogen.

It regulates sexual desire (libido), bone mass, fat distribution, muscle mass and strength, and red blood cells and sperm production in men.

A small amount of circulating testosterone is converted to estradiol, a form of estrogen.


As men get older, they often produce less testosterone, so they have less estradiol.

Therefore, the changes often attributed to testosterone deficiency could be partially or totally due to the accompanying decrease in estradiol.

How the body produces, distributes, and uses testosterone varies between men and women.


In men, the production of testosterone begins at puberty, when the pituitary gland in the brain starts to produce hormones called follicle-stimulating hormone (which primarily stimulates sperm production) and luteinizing hormone (LH).

LH is the hormone that stimulates a man’s testes to produce testosterone.

Cells in the testicles are called interstitial or Leydig cells to produce testosterone in response to LH production.

About 95% of a man’s testosterone is produced by Leydig cells.

The production of testosterone increases exponentially (approximately 18 times) during puberty.

After puberty, interstitial cells typically produce testosterone continuously.

Approximately 6 mg of testosterone is produced per day.

However, testosterone production can decrease in response to chronic ( obesity ) or transient health conditions.

In addition, men with hypogonadism do not produce testosterone because the pituitary glands or hypothalamus in the brain that produce the hormones that stimulate testosterone production are dysfunctional or because the testes are dysfunctional.

Testosterone production also decreases with age, and on average, men experience a 1% annual decrease in testosterone production once they reach 40 years.

The body does not use most of the testosterone produced by the testes. It is inactivated by the liver and excreted through the kidneys.

A small proportion (approximately 4%) of testosterone remains in man’s blood. It is converted into active forms of testosterone that can bind to other molecules in the blood or be used by the cells of the man’s body.

This can be used by cells in the body with androgen receptor sites, including hair follicle cells, bone cells, and cells of the seminiferous tubules of the testicles where the sperm is produced.

Most of the testosterone that remains in a man’s blood binds to other molecules in the blood.

About 44% of testosterone binds strongly to a carrier protein (a protein molecule that binds to other molecules and transports them in the blood) called sex hormone-binding globulin (SHBG).

Because testosterone is tightly bound, it can not be separated from SHBG and bind with other molecules and therefore is not available for the use of cells in the human body.

The portion of testosterone tightly bound to SHBG is called biologically inactive testosterone.

Another 54% of the testosterone in a man’s blood is attached to a second carrier protein called albumin.

As testosterone binds loosely to albumin, it can be separated from this protein and attached to other molecules in the blood or used by cells in the man’s body.

Weakly bound testosterone is considered bioavailable, which means that it is available for the use of cells in the human body.

The remaining 2% of testosterone in a man’s blood does not bind to other molecules. This free portion is known as free testosterone and is also considered bioavailable.

Chronic conditions (e.g., diabetes) and aging can alter the relative concentrations of free testosterone and SHBG bound to albumin in a man’s blood.

For example, the proportion of bioavailable testosterone decreases more rapidly as managed (at an annual rate of 2-3%) than the overall decrease in testosterone production (which occurs at about 1 percent). %).

The relatively significant reduction in bioavailable testosterone occurs because older men produce larger amounts of SHBG that strongly binds to testosterone, making it biologically unavailable or inactive.


In women, about 50% of the testosterone circulating in the blood is produced in the interstitial cells of the ovaries.

The adrenal glands and other tissues produce the rest of a woman’s testosterone.

Like a man’s testicles, a woman’s ovaries are stimulated to produce testosterone by LH signals.

Women produce much smaller testosterone than men, but it is an essential hormone for women.

Testosterone is the immediate precursor of estradiol. When the testosterone molecules in the body separate to form other hormones or molecules (a process known as biosynthesis), oestradiol is one of the biological products. Oestradiol is a hormone of the estrogen group.

Therefore, maintaining adequate testosterone levels is essential to preserving estrogen production.

Estrogens are the primary female hormones that regulate many reproductive functions, including ovulation, and are essential for women’s health and well-being.

Not all the testosterone produced by a woman will become estrogen; A proportion of testosterone will remain in a woman’s blood and bind to SHBG or albumin or circulate freely without attaching to any other molecule.

As with men, testosterone that binds to SHBG is not available for use by body cells, but free testosterone bound to albumin is bioavailable.

Bioavailable testosterone can be used by cells in the body with androgen receptor sites (sites that receive hormones from the group of androgens, including testosterone and the most prominent).

In women, androgen receptor sites are found in skin tissues, hair follicles, bones, and sebaceous glands (glands in the skin that secrete a fatty substance called sebum).

Low testosterone levels are present in girls from birth and approximately double during pubertal development.

After puberty and the start of regular menstrual cycles, testosterone levels in women fluctuate throughout the menstrual cycle.

They begin to increase in the first half of the cycle (also known as the follicular phase) and are at their highest point during the middle of the menstrual cycle.

As with men, the production of testosterone in women depends on age, and a woman’s testosterone production begins to decrease at 20 and continues until she reaches menopause.

By the time a woman reaches age 40, her circulating testosterone levels will be about half of what they were immediately after puberty.

Underlying causes of testosterone imbalance

The testosterone imbalance is caused mainly by the production of excessive or insufficient testosterone.

The underlying causes of imbalances in testosterone production vary for men and women.


In men, elevated testosterone levels can be caused by:

  • Use of anabolic steroids
  • For example, administration of too much exogenous testosterone (testosterone of external origin) in testosterone replacement therapy.

Testosterone deficiency is associated with the following conditions:

  • Primary hypogonadism: a condition in which testosterone production does not occur due to testicular dysfunction.
  • Secondary hypogonadism: a condition in which testosterone does not occur due to a dysfunctional hypothalamus or pituitary gland (the glands in the brain that produce hormones that stimulate testosterone production).
  • Obesity: An Australian study found that obese men were almost twice as likely as non-obese men to have a severe testosterone deficiency.
  • Chronic health conditions such as diabetes, metabolic syndrome, and cardiovascular diseases are associated with low testosterone levels.
  • VIH.

Some medications, particularly chemotherapy drugs used to treat cancer, corticosteroids, and alcohol, are associated with low testosterone levels.


In women, elevated testosterone levels can be caused by:

  • Polycystic ovarian syndrome: women with polycystic ovarian syndrome usually have high testosterone levels and other groups of androgens.
  • Idiopathic hirsutism: excessive hair growth of unknown origin.
  • Congenital adrenal hyperplasia: excessive growth of the adrenal gland caused by the development of excessive normal adrenal cells.
  • Ovarian or adrenal tumors that secrete androgens: tumors of the ovaries or the adrenal glands that produce and secrete hormones from the androgen group.
  • Exogenous testosterone administration: for example, as part of hormone replacement therapy.

Abnormally low levels of testosterone can be induced by:

  • Estrogen replacement therapy: the resulting increase in estrogen causes an increase in SHBG concentrations. This results in higher amounts of testosterone that bind tightly and are not biologically available.
  • Primary ovarian failure: failure of the ovaries to produce mature ovules or sufficient amounts thereof due to a dysfunction in the ovaries.
  • Secondary ovarian failure: failure of the ovaries to pay ovules due to a dysfunction in the pituitary gland, which means that the pituitary gland does not secrete the follicle-stimulating hormone, the hormone that stimulates the ovaries to develop mature ovules.
  • Hypopituitarism: reduced secretion of hormones from the pituitary gland.
  • Adrenal axis dysfunction: the axis of the hormone-secreting glands that are the adrenal glands located on the kidneys and the hypothalamus, and the pituitary glands in the brain.
  • Chemotherapy drugs
  • Surgical menopause: is associated with a rapid decrease in production and testosterone levels. For example, bilateral ooctoctopexy (removal of both ovaries) causes a quick (approximately 50%) decrease in testosterone levels.
  • Natural menopause: although the decline is gradual and the levels of testosterone in women begin to decrease throughout the reproductive years of a woman, before the onset of menopause.

Testosterone imbalance: side effects and symptoms


High levels of testosterone are associated with the following conditions:

  • Priapism: persistent erection.
  • Sudden cardiac death
  • Liver disease

Testosterone deficiency is associated with the following side effects and symptoms:

  • Reduction of libido.
  • Erectile dysfunction includes reduced penile rigidity during erection and shorter duration erections.
  • Oligospermia: low concentration of sperm in the semen.
  • Azoospermia: absence of sperm in the semen.
  • Mood changes and irritability.
  • Anorexia.
  • Depression: a large study reported that men with testosterone deficiency were four times more likely to have a clinically diagnosed depression.
  • Lack of energy.
  • Reduced cognitive function: poor concentration and increased risk of mental disorders, including Alzheimer’s disease.
  • Joint pains and stiffness.
  • Reduced bone mass: which increases the risk of osteoporosis.
  • Reduced muscle mass
  • Weight gain.
  • Reduced hemoglobin
  • Reduction of mortality.


In women, there is evidence that abnormally low levels of testosterone are associated with the following health problems:

  • Loss of bone mineral density: a measure of the thickness of mineral salts such as calcium carbonate in bone.
  • Osteoporosis.
  • Increased risk of hip fracture: in postmenopausal women.
  • Reduction of muscle strength: in postmenopausal women.
  • Loss of height: in postmenopausal women.
  • Reduction of lean body mass: in postmenopausal women.
  • Reduced function of cognition and memory.
  • Persistent fatigue
  • Reduced motivation
  • Loss of pubic hair.
  • It is thinning the vaginal mucosa: the membranes that produce vaginal mucus, including lubrication during sexual activity.
  • Reduced sense of well-being

Impairment of sexual functioning, which includes:

  • Reduced frequency of sexual relations.
  • Decrease in libido
  • Reduction of vaginal lubrication.
  • Dyspareunia: pain during intercourse.
  • Reduced orgasmic capacity
  • Removal of sexual pleasure.

Abnormally high testosterone levels in women can cause the excessive development of typically male sexual characteristics and can result in:

  • Hirsutism: excessive hair growth, for example, on the face or chest.
  • Acne.
  • Male pattern baldness.
  • Clitoromegaly: enlargement of the clitoris.
  • Deepening of the voice.

Testosterone was used for the first time as a clinical drug as early as 1937, but with little understanding of its mechanisms.

The hormone is now widely prescribed for men whose bodies naturally produce low levels.

However, the levels at which testosterone deficiency becomes medically relevant are not yet well known.

The average testosterone production varies significantly in men, so it is difficult to know what levels are of medical importance.

The mechanisms of action of the hormone are not precise either.

Quick facts about testosterone

Testosterone regulates a series of processes in the male body.

As men get older, their testosterone levels tend to decrease.

Prohormone supplements do not affect testosterone levels.

Testosterone supplements are prescribed only for specific conditions and do not counteract the natural decline of age-related testosterone levels.

Testosterone replacement therapy (TRT) is also available. However, this can have side effects and multiple risks.

Testosterone is produced mainly in the testes in men, with a small amount paid in the adrenal glands.

The production of testosterone is controlled by the hypothalamus of the brain and the pituitary gland.

The hypothalamus instructs the pituitary gland on the amount of testosterone it must produce, and the pituitary gland passes the message to the testes.

These communications occur through chemicals and hormones in the bloodstream.

Testosterone participates in developing male sex organs before birth and secondary sexual characteristics at puberty, such as deepening the voice, enlargement of the penis and testes, facial hair, and corporal growth.

The hormone also plays a role in sexual desire, sperm production, fat distribution, production of red blood cells, and maintenance of muscle strength and mass. For these reasons, testosterone is associated with general health and well-being in men.

A 2008 study published in the journal Frontiers of Hormone Research even linked testosterone to the prevention of osteoporosis in men.

In women, the ovaries and adrenal glands produce testosterone.

The women’s total testosterone levels are approximately one-tenth to one-twentieth of the men’s levels.

When a man has low testosterone or hypogonadism, he may experience:

  • Reduction of sexual desire.
  • Erectile dysfunction.
  • Low sperm count.
  • Breast tissue is enlarged or swollen.

Over time, these symptoms can develop in the following ways:

  • Loss of body hair.
  • Loss of muscle mass.
  • Increase in body fat.
  • Hot flushes.
  • Depression, irritability, and inability to concentrate.
  • Loss of strength
  • Testicles shrunk and smoothed.
  • Loss of muscle mass or hair.

In progress, chronic or low testosterone can cause osteoporosis, mood swings, reduced energy, and testicular contraction. Causes can include:

  • Testicular injury: like castration.
  • Infection of the testicles.
  • Medications: as opioid analgesics.
  • Disorders that affect hormones: such as pituitary tumors or high prolactin levels.
  • Chronic diseases: include type 2 diabetes, kidney and liver disease, obesity, and HIV / AIDS.
  • Genetic diseases: such as Klinefelter syndrome, Prader-Willi syndrome, hemochromatosis, Kallman syndrome, and myotonic dystrophy.

Too much testosterone, on the other hand, can cause puberty before age 9. This condition would mainly affect younger men and is much rarer.

In women, however, high testosterone levels can lead to male pattern baldness, a harsh voice, and menstrual irregularities, as well as:

  • Changes in body shape.
  • Reduction in breast size.
  • Oily skin.
  • Facial hair growth: around the body, lips, and chin.

Recent studies have also linked high testosterone levels in women with the risk of uterine fibroids.

Testosterone imbalances can be detected with a blood test and treated accordingly.

Testosterone therapy

For people worried about low or high testosterone, a doctor can perform a blood test to measure the amount of the hormone in the patient’s blood.

When doctors find low T, they can prescribe testosterone therapy, in which the patient takes a synthetic version of the hormone.

This is available in the following forms:

  • A skin patch: placed on the body or scrotum twice a day.
  • A solution was applied to the armpit.
  • Injections: every two or three weeks.
  • A gel is applied to the upper part of the arms, shoulders, or abdomen daily.
  • One patch: on the gums twice a day.
  • Implants: lasting from four to six months.

Men who use testosterone gels should take precautions, such as washing their hands and covering the areas where the gel is applied.

Children and women should not touch the skin where the patch or gel is applied.

Experts say that testosterone treatment has increased strength and sexual desire in older men with actual testosterone deficiencies.

However, sometimes, the symptoms of erectile dysfunction are due to other conditions, such as diabetes and depression, according to the Mayo Clinic.

Treating these men with testosterone will not improve symptoms.

There are many other claims about what testosterone therapy can do, but they are also being tested.

In a 2017 study published in the American Medical Association (JAMA), testosterone treatments corrected anemia in older men with low testosterone levels better than a placebo.

Another 2017 study published in JAMA found that older men with low testosterone levels had increased resistance and bone density after treatment compared with a placebo.