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Understanding Testosterone

Wednesday 21 February 2024
6 minute(s) read

Table of Contents

I. What is Testosterone?

II. Testosterone In Males

III. Testosterone In Females

IV. High Levels of Testosterone

V. Low Levels of Testosterone

VI. Testosterone Therapy

VII. Conclusion

Testosterone is often thought of as the "male hormone," but it plays an important role in the health of both men and women. While testosterone is responsible for the development of stereotypically male characteristics like facial hair and a deep voice, it also contributes to sexual health and function in women as well.

In this article we’ll discuss what testosterone is, how it contributes to sexual development and sexual health, the impact of abnormal levels of testosterone, and testosterone therapy.

What is Testosterone?

3D structure of testosterone

Testosterone is a crucial hormone for both males and females. It’s responsible for the development of male growth and masculine characteristics, as well as playing an important role in female sexual health. [1]

Hormones, including testosterone, act as the body's chemical messengers, traveling from one organ to another through the bloodstream. [1] The production of testosterone is a complex process that involves several organs:

  • The brain sends signals to the pituitary gland to produce testosterone
  • The pituitary gland sends signals to the testes to start producing testosterone
  • If testosterone levels rise too high, the brain sends signals to the pituitary gland to reduce production [1]

It's important to note that testosterone levels can vary significantly over time and even throughout the day. [1]

Testosterone In Males

Testosterone, the primary male sex hormone, plays a crucial role in the development and functioning of the male body. During puberty, testosterone levels rise, triggering a series of changes that lead to the development of male characteristics. [1]

  • Voice deepening: Testosterone causes the larynx, or voice box, to grow. This deepens the voice from a high pitch to a lower tone. [2]
  • Facial and body hair growth: Testosterone triggers hair follicles on the face, underarms, chest, and pubic area to produce coarse, dark hairs. [3]
  • Male pattern baldness: DHT (a by-product of testosterone) can contribute to male pattern baldness in adulthood. This genetic condition causes hair loss at the temples and crown of the head over time. DHT can cause the hair follicles in these areas to shrink, making the hairs finer and weaker until they fall out completely. [4]
  • Muscle size and strength: Rising testosterone prompts muscle cells to create more protein, which builds more muscle mass. [5]
  • Sperm production: Testosterone works with other sex hormones to help generate sperm cells. Adequate testosterone levels are crucial for male fertility. [6]
  • Bone growth and strength: During puberty, testosterone helps increase bone density, contributing to the overall development of a strong skeletal system. This is particularly important in preventing osteoporosis and maintaining bone health later in life. [1]

Testosterone In Females

Testosterone is often thought of as a "male" hormone, but it plays an important role in women's health as well. While women have much lower levels of testosterone compared to men, this hormone affects several aspects of a woman’s reproductive health. [1]

  • Sex drive: Testosterone is involved in libido and sexual function for both men and women. Women with lower testosterone levels may notice a decrease in sexual desire.
  • Bone strength: Testosterone plays a part in bone density and preventing osteoporosis. Declining testosterone as women age is one factor that increases the risk of weakened bones. Ensuring testosterone levels don't drop too low with age promotes bone health.
  • Ovarian function and fertility: Normal testosterone levels support regular ovulation and a woman's ability to get pregnant. When testosterone is too high or too low, it can lead to irregular periods and challenges with conception. [1]

High Levels of Testosterone

While testosterone is an important hormone, having too much can lead to issues for both men and women.

In men, high levels of testosterone are rarely a problem, but when it occurs, it can lead to serious health concerns. Most of what we know about high levels of testosterone in men comes from athletes who use testosterone as a performance-enhancement drug. [1] Potential problems from high testosterone levels in men include:

  • Low sperm count
  • Shrinkage of the testicles
  • Prostate enlargement [1]

Women also experience the negative effects of too much testosterone. Polycystic ovarian syndrome (PCOS) is a condition that affects 6% to 10% of women and is often associated with high testosterone levels. [1] Symptoms of PCOS include:

  • Irregular periods
  • Reduced fertility
  • Excess hair on the face, extremities, or pubic area
  • Weight gain
  • Depression
  • Anxiety [1]

Treatment for elevated testosterone in women often includes medications like spironolactone that block the effects of testosterone. [1]

Low Levels of Testosterone

As men age, their testosterone levels gradually decline. This natural drop occurs at a rate of 1% to 2% each year. This is because the liver starts producing a compound called sex hormone binding globulin (SHBG). This compound binds to testosterone circulating in the bloodstream, making less testosterone available for the body to use. [1]

Over a third of men will have lower-than-normal testosterone levels after the age of 45. [1] While this decline is normal for aging, it can lead to undesirable symptoms if levels drop too low.

  • Decreased facial and body hair growth
  • Reduced sex drive and erectile dysfunction
  • Increased breast tissue growth
  • Loss of muscle mass and strength
  • Hot flashes
  • Irritability and mood changes
  • Erectile dysfunction (ED)
  • Osteoporosis and brittle bones [1]

Low testosterone can also have an impact on women. When testosterone levels are low in women, it can lead to:

  • Low sex drive
  • Reduced bone strength
  • Difficulties with concentration
  • Depression [1]

Testosterone Therapy

Vials of testosterone and an injection needle

Testosterone therapy, which supplements the body's testosterone levels, can be an effective treatment for men and women experiencing low testosterone.

  • For men, testosterone therapy is approved to treat delayed puberty in adolescent boys, as well as abnormally low testosterone levels caused by problems with the testes, pituitary gland, or hypothalamus.
  • For women, testosterone therapy may help relieve symptoms that can accompany low testosterone levels, such as low sex drive, fatigue, and mood changes. [1]

While testosterone therapy can be beneficial for many people, some individuals may experience side effects, especially when first starting treatment. Common side effects include:

  • Acne
  • Difficulty breathing during sleep
  • Breast swelling or tenderness
  • Ankle swelling
  • High red blood cell counts
  • Stimulation of prostate cancer cell growth in men [1]


Understanding the role of testosterone in both males and females is crucial for maintaining overall health and well-being. Testosterone plays an integral role in many areas of health, from mood and libido to bone and muscle health.

If you're concerned about your testosterone levels or experiencing any related symptoms, it's always best to consult with a healthcare professional. They can provide personalized guidance and help you optimize your hormonal balance for optimal health and wellness.  

If you have more questions about testosterone, visit our dedicated testosterone blog for more topics.

The content provided in this article is based on thorough research and in some cases, reviewed by a medical professional. Our goal for the information is to provide helpful, general health information. It is not intended as a substitute for professional medical advice.