An Introduction to Testosterone and its Metabolites: What Testosterone Does and Doesn’t Do

Testosterone boosters in the market boast of enhancing your performance, stamina, and endurance. They claim to help you lose fat, build muscle faster, gain vitality and boost sex drive.

Is testosterone really that powerful? What exactly is testosterone? What can it really do?

Testosterone is a hormone, which is important for both men and women.

Read on to find out the answers you are looking for. Learn how testosterone is produced in our bodies and the role it plays in our health.

What is Testosterone?

Testosterone is the main sex hormone in men. It plays a key role in sexual health and reproduction.

Testosterone has a strong influence on how a man looks – how tall he is, his build, muscularity, strength, hair growth, and much more (1, 2, 3). It also impacts his behavior and cognitive abilities.

(Read more about these in the sections below  – the role of testosterone in men and women.)

How is Testosterone Produced?

Testosterone is mainly produced by the gonads. The primary reproductive organs in men and women are called the gonads. In men, testosterone is produced by the male gonads – the testes. Female gonads are the ovaries.

The adrenal glands also produce small quantities of testosterone, in both genders.

There is a small gland that is present below the brain, known as the pituitary gland, and just above it is an area of the brain called the hypothalamus. Both of them together control the amount of testosterone produced in our body.

Depending on the levels of testosterone in the blood, the hypothalamus tells the pituitary gland to release a hormone called LH (luteinizing hormone), which travels in through the blood to reach the gonads and stimulate the production of testosterone. 

Testosterone to Estrogen Conversion

Some of the testosterone in men is converted to estrogen. For optimum health, estrogen levels have to be in balance with testosterone levels. Estrogen is needed for regulating sex drive, sperm production, and erection in men (4).

Estrogen is the primary female sex hormone. Estrogen is actually an umbrella term referring to 3 hormones that display estrogenic activities – estradiol, estrone, and estriol.

Estrone and estradiol are the two main types of estrogen found in men. 

Hormones that play important roles in male traits and reproduction are known as androgens (male hormones). Testosterone and Androstenedione (ASD) are the two principal androgens.

Androgens are converted to estrogen by a process called aromatization. Aromatase is the main enzyme involved in this process. Androstenedione can be converted to either estrone or testosterone, as required by the body. Testosterone is also converted to estradiol by aromatase.

Testosterone Metabolites

Here’s a short introduction to some terms you may come across during your search on testosterone.

DHT: Dihydrotestosterone (DHT) is formed during the breakdown of testosterone. Such breakdown products are called metabolites. In both men and women, around 10 percent of testosterone is converted into DHT.

Along with testosterone, DHT plays a role in the development of male sex characteristics. It is required to initiate the onset of puberty in boys. DHT is believed to be responsible for male pattern baldness and hair loss (5).

Other Testosterone Metabolites: Androstanediol glucuronide (ADG or 3α-ADG ) is formed from the breakdown of DHT. Androsterone is a by-product of testosterone and DHT metabolism (6). Etiocholanolone, on the other hand, results from testosterone and androstenedione metabolism (7).

Role of Testosterone in Men

Testosterone is much more than just a sex hormone. It plays a variety of roles in a man’s health and well-being. 

  • Development of reproductive organs: It is required for the development of sexual organs such as the penis and testicles at puberty. 
  • Development of male characteristics: As a boy enters into manhood, testosterone stimulates the growth of hair in the face, underarms, and pubic region. More body hair may also start growing. Deepening of the voice and the growth of Adam’s apple also occurs around this time.
  • Fertility: Testosterone is required for the production of sperm. Low testosterone levels can cause a drop in sperm production.
  • Regulates libido and erection: Testosterone stimulates the sex drive. This hormone is needed for erection and ejaculation. It dilates the blood vessels and increases blood circulation to the penis to maintain an erection. 
  • Increases and strengthens muscle mass: Testosterone boosts muscle protein synthesis and the production of red blood cells. When men exercise and work out, testosterone helps build bigger and stronger muscles.
  • Maintains bone health: Testosterone is required for keeping your bones strong and healthy. It increases bone density. Those with low testosterone often have osteoporosis. There is an increased risk of fractures (8). 
  • Safeguards the cardiovascular system: Testosterone plays a role in maintaining healthy cholesterol levels (9). Keeping these under control safeguards your cardiovascular system. As a vasodilator, testosterone improves blood flow in the arteries (x). This is good for the heart and its functions.
  • Improves pelvic floor and continence: The ability to control bowels and bladder movements is called continence. The pelvic floor muscles support both the bladder and bowel. Testosterone helps in keeping the pelvic muscles strong and flexible (10).
  • Improves mood: Men with low testosterone may have depression and be moody. Testosterone helps increase the levels of the feel-good hormone, dopamine in the body (11). This improves mood, making you feel happier and motivated.
  • Improves memory: Testosterone is important for memory and mental functions in men. Low testosterone levels can lead to poor cognitive function and memory impairment. Supplementing with testosterone seems to help improve these problems (12, 13).
  • Discourages obesity: Obesity and testosterone are strongly interconnected (14). Testosterone can help suppress fat gain and increase muscle gain (15). Low testosterone can lead to weight gain. On the other hand, being fat can be a reason for low testosterone. Fat cells in the body convert testosterone to estrogen. This causes estrogen to rise and testosterone levels to fall. 

Role of Testosterone in Women

Even though it’s considered a male hormone, testosterone plays many roles in women’s health. Testosterone is crucial starting from supporting the growth of their reproductive organs to strengthening muscles and bones. 

Let us take a quick look at the many roles of testosterone in women:

  • Enhancement of sex drive: Testosterone stimulates sex drive in women too. Women tend to have very low testosterone levels after menopause. Their sexual desire also tends to decrease post-menopause. Testosterone is prescribed off-label for treating low sex drive after menopause (16, 17).
  • Maintenance of the female genitals: Testosterone is required for the development of female sex organs in a fetus (18). It also supports the growth and maintenance of women’s reproductive organs.
  • Improves bone density: Testosterone decreases bone loss and supports bone growth in the body. Low testosterone in women, mainly after menopause, increases the risk of osteoporosis.
  • Improves mood, reduces depression: Testosterone influences mood in women too. Both low or high levels of testosterone can cause depression in women (19)
  • Improves muscle mass and strength: Testosterone helps in increasing muscle mass and strength in women. It plays an active role in muscle growth. Low levels of testosterone decrease in muscle tone (20). This can affect the joints, stability, and balance. It can also affect your posture and flexibility.
  • Improves incontinence: Urinary incontinence is a condition in which you lose control over your bladder. Low testosterone is associated with incontinence in women (21). Women also require testosterone for supporting pelvic floor muscles.

The Final Note

Testosterone is normally associated with male reproductive functions. However, it does much more than that. It is not only responsible for healthy bone, muscles and red blood cell production, testosterone also affects mental health both in men and women.

In females, testosterone combined with estrogen helps in the development of reproductive organs as well as being responsible for menstrual health.

Abnormally high or low levels can affect both men and women. 

Read more: Low Testosterone Part 2: The Causes of Low T
About Anju Mobin 33 Articles
Anju Mobin is a certified nutritionist with a 3-year graduate degree in B.Sc. Home Science (Clinical Nutrition and Dietetics). With an additional 4-year graduate degree in Fine Arts (BFA Applied Arts), she combines her passion for advertising with her knowledge of the health industry to create, develop and execute content marketing campaigns for healthcare products. She is the founder and managing editor of the health website fitnesshacks.org.