Where Is Testosterone Produced in the Body?

Key Takeaways:

• In men, testosterone is produced primarily in the testes, with a small amount produced by the adrenal glands.

• Testosterone production is controlled by the endocrine system and also involves the brain, other glands, and several key hormones.

• Factors that affect testosterone production include certain medical conditions as well as everyday habits, including diet, movement, and sleep.

It would be easy to argue that testosterone is one of the most important hormones in your body. Just a few examples of its essential functions include supporting your sexual health, mood, and ability to maintain muscle.

With all that in mind, you might be wondering: Where is testosterone produced? most men, the overwhelming majority of testosterone is produced in the testes, although other glands and hormones are involved in the process.

Read on to learn more about where testosterone is made in the body and how to support healthy testosterone production.

Testosterone is the main male sex hormone. It’s classified as a steroid hormone, meaning your body makes it from a fatty molecule called cholesterol. 

For men who have normal testicle function, more than 95 percent of testosterone is produced in the testes — specifically in specialized cells called Leydig cells. One of the other main functions of your testicles is to produce sperm, but this process happens in different cells.

Testosterone levels are tightly controlled by a feedback loop involving your brain (specifically, the hypothalamus), your anterior pituitary gland, and other hormones they produce. Collectively, this pathway of hormones is known as the hypothalamic-pituitary-gonadal (HPG) axis.

Here’s how the HPG axis works:

• Hypothalamus: If circulating levels of testosterone in your blood are low, a small region in your brain called the hypothalamus releases gonadotropin-releasing hormone (GnRH).

• Anterior pituitary gland: GnRH travels to your anterior pituitary gland, located at the base of your brain. This gland responds to GnRH by secreting luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

• Testes: LH travels through your bloodstream to the Leydig cells in your testes, telling them to produce testosterone. Similarly, FSH acts on different cells in your testicles to start sperm production.

Men who don’t have normal testicle function or have had their testicles removed usually need to take hormone replacement therapy to supplement their natural testosterone levels.

A small amount of testosterone, usually less than 5 percent, is made in the adrenal glands, which sit on top of your kidneys. These glands also produce the hormone cortisol, sometimes nicknamed the “stress hormone.”

Your adrenal glands don’t produce testosterone directly. Instead, your adrenal glands secrete weaker androgen hormones such as androstenedione and dehydroepiandrosterone (DHEA). These hormones can be converted into testosterone in other areas of the body, including your:

• Fat

• Skin

• Liver

Some medical conditions, such as congenital adrenal hyperplasia (CAH), can cause an under- or overproduction of testosterone.

CAH is a group of genetic conditions that lead to changes in the enzymes inside your adrenal glands, such as 21-hydroxylase or 11β-hydroxylase. These imbalances can lead to alterations in levels of cortisol, testosterone, and other hormones.

While we’ve talked a lot about testosterone production in men, it’s worth noting that women also produce testosterone — just in much smaller amounts. Likewise, the hormone estrogen is present in males in smaller amounts than in females.

In women, adrenal androgens are the main source of testosterone. Like with males, the adrenal glands produce other androgen hormones that need to be converted by tissues such as skin or fat.

The ovaries also produce some DHEA that can be converted into testosterone. Some conditions, such as polycystic ovary syndrome (PCOS), can lead to the overproduction of testosterone.

Testosterone is the main “male” hormone that gives men their masculine traits. Tissues throughout your body, such as your brain, muscles, and bones, have androgen receptors. For testosterone to affect your body, it needs to bind with these receptors.

Only roughly 1 to 4 percent of the testosterone in your body is known as free testosterone. This form is biologically active and capable of binding to receptors in tissues.

The rest of your testosterone is bound to proteins — mainly sex hormone-binding globulin (SHBG) and albumin. Although these forms of testosterone don’t directly act on your tissues, they act as a “storage reservoir” that your body can tap into if levels get too low.

If you receive a blood test to check your testosterone levels, you’ll likely have both your total testosterone and free testosterone levels measured.

Function of Testosterone

As we mentioned, testosterone plays many essential functions in your body. High levels of testosterone are needed for the development of male traits during puberty. Conditions that impair testosterone levels through adolescence, such as Kallmann syndrome, often lead to delayed or a lack of puberty without hormone therapy.

Testosterone acts on almost every system in the male body. Some examples of its functions include:

• Allows the maintenance of muscle mass and strength

• Promotes bone density and growth and prevents osteoporosis

• Influences sex drive and sexual function

• Affects mood and energy levels

• Regulates fat distribution

• Stimulates red blood cell production

• Supports sperm production

• Supports body, facial, and pubic hair growth

Testosterone levels can rise or fall based on your daily habits or underlying medical conditions. Here are some of the key factors that affect its production.

Diet and Nutrition

A balanced diet rich in essential nutrients is crucial for optimal testosterone production. If you don’t get enough nutrients from your diet, your body might not have the raw materials it needs to produce testosterone. 

Severe energy deficiency, meaning not eating enough calories to support your body weight, has been associated with lower testosterone levels. Not getting enough essential nutrients, such as zinc, may also be linked to lower testosterone. 

Read more about foods that affect testosterone levels.

Exercise

Resistance training, weight lifting, and high-intensity interval training (HIIT) may increase testosterone levels, at least temporarily. Moderate to intense exercise, in particular, seems to be associated with larger increases in testosterone. 

While the boost may be short-lived, getting regular exercise supports weight management and overall health, which can, in turn, support testosterone production.

On the other hand, excessive endurance exercise or overtraining can have the opposite effect.

Read more about the connection between exercise and testosterone.

Sleep

Your body requires sleep to help support many essential functions, such as maintaining and replenishing your testosterone and other hormone levels. Research consistently shows that lack of sleep is associated with lower testosterone levels. 

Adults should aim for seven or more hours of quality sleep each night

Read more about the connection between sleep and testosterone.

Chronic Stress

Chronic stress increases cortisol, a hormone that can directly inhibit the HPG axis responsible for testosterone synthesis in the testes.

Body Fat

Having excess fat tissue, especially around the abdomen, can increase aromatase — an enzyme that converts testosterone into estrogen. Maintaining a healthy body fat percentage helps preserve optimal testosterone balance.

Read more about weight loss and testosterone. 

Alcohol and Drug Use

Heavy and long-term alcohol consumption and some prescription or recreational drugs — such as anabolic steroids — can impair testicular function and lower testosterone levels. 

Medical Conditions

Conditions such as diabetes, obesity, and some genetic conditions can interfere with the HPG axis, leading to reduced testosterone output. 

If you suspect your testosterone might be low, a blood test can confirm it. Most doctors test for total testosterone and free testosterone. Doctors also often recommend testing LH and FSH to understand whether the issue lies in the testes or other parts of your body. 

Normal testosterone levels for adult men are often considered 300 to 1,000 nanograms per deciliter (ng/dL), but the exact cut-off values vary between labs. 

We offer testing kits that allow you to measure your testosterone levels at home without the need to go to a clinic in person. Your results will be analyzed by a healthcare professional who will help you understand what your results mean.

There are many ways you can help support your testosterone levels. Some ways include:

• Regular strength training 

• Getting plenty of high-quality rest

• Eating a balanced diet filled with healthy fats, adequate protein, and nutrients like zinc, magnesium, and vitamin D

• Managing stress by scheduling more relaxing activities into your day and finding time for things you enjoy

• Limiting alcohol and recreational drugs

• Maintaining or achieving a healthy body weight.

Sometimes lifestyle habits alone aren’t enough to maintain proper hormone levels, especially in people with genetic conditions like Klinefelter syndrome.

In these cases, your doctor may recommend testosterone replacement therapy (TRT). TRT is generally safe but may cause side effects. Your healthcare provider can best advise you about the pros and cons.

We offer online consultations with licensed professionals who can assess whether you may make a good candidate for TRT. If you do make a good candidate, they can prescribe TRT for you without the need to go to a clinic in person. 

Testosterone is the main male sex hormone. It plays many essential roles in supporting your well-being, such as maintaining your libido, muscle mass, and body hair.

For adult males, the majority of testosterone is produced in the Leydig cells of the testes. Your testes require signals from hormones produced in your anterior pituitary gland and hypothalamus to produce testosterone. 

A small amount of testosterone is made in your adrenal glands. This amount is generally insignificant for most people with normal testicle function. 

If you suspect you may have a hormonal problem, it’s a good idea to speak to a specialist in endocrinology. We offer online consultations with licensed professionals who can help evaluate your hormonal health.

What is the normal range of testosterone?

Blood levels of testosterone are generally considered normal between about 300 to 1,000 nanograms per deciliter (ng/dL). The exact cut-off values vary between labs, and some might not consider testosterone levels low until they dip under 250 ng/dL. 

What does testosterone do?

Testosterone supports many aspects of male health, including your libido, muscle mass, and male characteristics like a deep voice and body hair. Testosterone also helps produce red blood cells.

Low testosterone levels can cause problems like mood changes, trouble maintaining muscle, and low sex drive. Too much testosterone can lead to aggression and other changes to your health, such as an increased risk of cardiovascular disease. 

Do the testicles make most of the testosterone in the male body?

Yes, for most males, the testicles produce about 95 percent of the testosterone in the body. The remainder is produced by the adrenal glands.