Testosterone is a male sex hormone. It is the main hormone in the male reproductive system, and it plays an important role in the development and maintenance of male reproductive organs [1]. Testosterone is also responsible for many other changes in boys during puberty, including:
- Increased muscle mass and strength
- Growth of facial and body hair
- Deepening of the voice
How Testosterone is Made
Testosterone is produced in the testes [1]. The testes are two small, oval-shaped organs that are located in the scrotum. The scrotum is a sac of loose skin that hangs behind the penis.
The production of testosterone is controlled by two other glands in the body:
- The hypothalamus: This is a small area of the brain that is located just above the brainstem. The hypothalamus is responsible for releasing hormones that control many different bodily functions, including the production of testosterone.
- The pituitary gland: This is a small gland that is located at the base of the brain. The pituitary gland releases a hormone called luteinizing hormone (LH). LH travels through the bloodstream to the testes, where it stimulates the production of testosterone [1].
How Testosterone Works
Testosterone works by binding to androgen receptors in cells throughout the body. Androgen receptors are proteins that are found in the nucleus of cells. When testosterone binds to an androgen receptor, it causes the cell to produce certain proteins. These proteins are responsible for the many effects of testosterone on the body, including:
- Muscle growth and strength
- Bone growth and density
- Sperm production
- Sex drive
- Red blood cell production
When Testosterone Levels Are High
Testosterone levels are highest during puberty and young adulthood. They begin to decline gradually after age 30 [2]. However, high testosterone levels can also be caused by certain medical conditions, such as:
- Anabolic steroid use
- Testicular tumors
- Congenital adrenal hyperplasia
When Testosterone Levels Are Low
Testosterone deficiency is a condition that occurs when the body does not produce enough testosterone. It is a common condition, especially in older men. Symptoms of testosterone deficiency can include:
- Decreased libido
- Erectile dysfunction
- Fatigue
- Loss of muscle mass
- Increased body fat
- Hair loss
- Mood swings
- Difficulty sleeping
When Testosterone Levels Drop
Testosterone levels naturally decline with age. This decline can begin as early as age 30 [2]. However, the rate of decline varies from man to man. Some men may not experience any noticeable symptoms of testosterone deficiency. Others may experience mild symptoms. And still others may experience more severe symptoms.
What Testosterone Level is Normal
The normal range for testosterone levels can vary depending on the lab test used. However, in general, a total testosterone level of 300 nanograms per deciliter (ng/dL) or higher is considered normal for adult males [2].
Testosterone Deficiency Treatment
Testosterone deficiency can be treated with testosterone replacement therapy (TRT). TRT is a treatment that involves replacing the testosterone that your body is not producing. TRT can be given in a number of different forms, including:
- Injections
- Gels
- Patches
TRT can be effective in improving symptoms of testosterone deficiency. However, it is important to discuss the risks and benefits of TRT with your doctor before starting treatment. Some potential side effects of TRT include:
- Increased risk of heart attack and stroke
- Sleep apnea
- Increased breast size
- Shrinking testicles
- Fertility problems
If you are concerned that you may have testosterone deficiency, please see your doctor. They can measure your testosterone levels and discuss whether TRT is right for you.
Disclaimer: I am not a medical professional. This blog post is for informational purposes only and should not be taken as medical advice. Please see your doctor for any questions or concerns you may have about testosterone or testosterone deficiency.