As the primary male sex hormone, or androgen, testosterone regulates various aspects of your growth and development as a man.
As the primary male sex hormone, or androgen, testosterone regulates various aspects of your growth and development as a man. Testosterone plays a central role in shaping both your physical characteristics and reproductive functions, like your testicular and penis growth, sperm production, muscle mass, and deeper voice. It also influences your sex drive, bone density, mood, and even distribution of body fat.
In this guide, we’ll explain why testosterone is so important, where it’s made in your body, and what happens if your hormone levels get too low or too high.
Testosterone, a natural steroid hormone, may help put hair on your chest and boost your arm-wrestling skills, but it does a lot more than just fuel body hair and grip strength.
Testosterone regulates numerous functions in the body, including:
Growth and development of the penis and testes
Sperm production
Muscle size and strength
Bone density
Hair growth (including pubic hair and facial hair)
Deepening of the voice during puberty
Red blood cell production
Sex drive (libido)
Though it’s primarily thought of as a male hormone, women produce testosterone, too, though in much smaller amounts. Men have about 20 to 25 times more testosterone than women. In women, most testosterone is made in the ovaries and converted to estrogen. As in men, testosterone is an essential hormone in women, thought to contribute to sex drive, bone strength, cognitive function, and cardiovascular health.
Testosterone is primarily produced in the gonads (the primary reproductive organs), specifically the testes in men and the ovaries and adrenal glands in women.
But testosterone production relies on chemical messages between glands in your brain and cells within the gonads.
Here’s a quick breakdown of how your body makes testosterone:
It starts with your hypothalamus. Your hypothalamus, a region in your brain, produces and secretes gonadotropin-releasing hormone (GnRH).
GnRH stimulates the pituitary gland. The release of GnRH stimulates the production and release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the anterior pituitary, the front lobe of the pituitary gland at the base of your brain.
LH and FSH send messages to your testes. Once LH and FSH enter your circulation, they travel to the gonads. LH signals the Leydig cells in your testicles to make testosterone (from cholesterol), and FSH calls on your Sertoli cells to produce sperm.
Though this is the primary route the hormone is made, your adrenal glands, which play a vital role in your metabolism and stress response, also produce minimal amounts of testosterone.
Testosterone levels are measured using a simple blood test. Low testosterone (hypogonadism) is usually diagnosed after two separate early-morning testosterone blood tests, taken between 8 and 10 a.m. on different days. According to the American Urological Association (AUA), the standard range for normal testosterone levels in adult males is 300 to 1,000 nanograms per deciliter (ng/dL). A level of 300 ng/dL is commonly used as a threshold to indicate low testosterone.
However, it’s normal for your testosterone to fluctuate throughout your life and even throughout each day.
Testosterone levels typically start declining when a man turns 40, by about 1 to 2 percent per year, according to some estimates, and continue to decline with advancing age. Producing less testosterone as an older man doesn’t necessarily require treatment unless it starts affecting your well-being. Low T is linked to symptoms like erectile dysfunction, fatigue, weakness, and other health conditions (more on that below).
Though the AUA lists >300 ng/dL as “normal” testosterone, some experts believe this cutoff doesn’t work as well for young, healthy men. In a 2022 analysis, researchers proposed total testosterone ranges for younger men:
20-24 years: 409-558 ng/dL
25-29 years: 413-575 ng/dL
30-34 years: 359-498 ng/dL
35-39 years: 352-478 ng/dL
40-44 years: 350-473 ng/dL
If you’re struggling with fatigue, sexual dysfunction, decreased muscle mass, increased body fat, and other hallmark symptoms of low T and your total testosterone blood test comes in under 300 ng/dL, you may be struggling with male hypogonadism, or low testosterone.
However, it’s important to remember that how you feel tells a more accurate story than the numbers on your chart. If you have low T symptoms but so-called “normal” testosterone levels, your provider may still consider treating you for low testosterone after ruling out other medical conditions.
Your provider might also decide to test your free testosterone levels, which is the amount of testosterone that is unbound to proteins and considered to be more “active” in your body.
Some of the most common symptoms of low testosterone, or testosterone deficiency, are:
Low libido
Infertility
Fatigue
Loss of muscle mass
Decreased bone density
Increased body fat
Less body hair
Hot flashes
Testicular shrinkage
Breast enlargement (gynecomastia)
Sleep disturbances
Mood changes
Memory trouble
Reduced red blood cell count
Low T can be related to genetic conditions like Klinefelter syndrome, pituitary disorders, certain medications, obesity, and more.
Causes of low testosterone also depend on the type you have. Primary hypogonadism, for instance, is caused by a problem involving the testicles. Secondary hypogonadism originates in the brain.
Potential causes of primary hypogonadism include:
Klinefelter syndrome, in which you have an extra X chromosome
Testicular injuries
Undescended testicles
Infections like mumps orchitis
Cancer treatments
Common causes of secondary hypogonadism include:
Kallmann syndrome (abnormal development of the hypothalamus)
Pituitary tumors or disorders
Inflammatory disease
HIV/AIDS
Obesity
Certain medications, like opiates
You may think having extra-high testosterone would lead to more strength, vitality, and maybe an impressive beard. But it is possible to have too much testosterone. If your total testosterone is consistently more than 1,000 ng/dL, you may notice mood swings and other undesirable symptoms.
Some potential signs that your testosterone is too high include:
Early puberty
Sleep problems and tiredness
Hair loss and baldness
Acne
Aggression and impulsivity
Heart or liver problems
A 2020 study found men with consistently high testosterone levels had greater bone density and less body fat than those with average T levels. However, they also showed lower HDL (“good”) cholesterol and higher rates of prostate cancer, male pattern baldness, and elevated blood pressure.
Some potential causes of high testosterone include:
One of the most popular FDA-approved treatments for low testosterone is testosterone replacement therapy, which comes in the form of injections, topical creams and gels, patches, oral formulations, and pellets.
This treatment uses synthetic testosterone to increase your circulating testosterone levels and effectively reduce symptoms of low T. The effects of testosterone therapy include improved libido and sexual function, increased muscle mass, enhanced body composition, better bone density, higher mood, and improved quality of life. However, TRT does come with potential side effects, including fertility issues.
TRT may be a first-line treatment for low T, but it’s not the only option. Oral medications that boost testosterone, such as clomiphene (Clomid®), stimulate the pituitary gland to increase FSH and LH and help your body make more of its own testosterone . These medications are used off-label to increase testosterone.
Another oral medication that can improve symptoms of low T is human chorionic gonadotropin (hCG), which helps nudge the Leydig cells in the testes to produce more testosterone.
Your healthcare provider may also recommend treating symptoms of low testosterone, such as erectile dysfunction, with oral ED medications like sildenafil (Viagra®) and tadalafil (Cialis®).
If you think you could use more support, get advice from a healthcare provider today to ask about these medications and other strategies to boost your testosterone and improve your sex life.
For men with low testosterone, doctors typically suggest starting with lifestyle changes before considering medication—unless testosterone levels are extremely low and symptoms are severe enough to warrant immediate testosterone replacement therapy (TRT).
In fact, certain lifestyle habits may help slow the natural decline in testosterone that occurs with age and increase testosterone naturally:
Improve your diet. Aim to eat a well-rounded diet with plenty of fresh fruits, leafy green vegetables, and fatty fish. Find out which superfoods made our list of the top foods that boost testosterone and which foods might kill your T levels. While a healthy diet alone can't treat low testosterone, eating the right foods may help support natural testosterone production.
Lose excess weight. Obesity has been linked to lower testosterone. Eating a nutritious diet and exercising regularly can help you reach a healthy number on the scale. But if you’re at a plateau, talk to your provider about what other weight loss treatments are available.
Add resistance exercises to your routine. Studies show that heavy resistance training increases testosterone immediately after exercise in men.
Get more high-quality sleep. Most of your testosterone is made while you’re asleep. Aim to get at least seven to eight hours of rest per night if you’re trying to maintain healthy T levels. One small, preliminary study found when men only slept five hours per night for one week, their testosterone declined by 10 to 15 percent.
Manage other health conditions. Health problems like high blood pressure, high cholesterol, type 2 diabetes, and more raise your risk of low T. Work with your provider to manage these conditions as needed.
Watch your stress levels. Some research suggests high cortisol is associated with low testosterone. Practicing mindfulness, talking with a therapist, and making lifestyle tweaks to your sleep, diet, and fitness routine can help you manage your stress more effectively.
Consider supplements. While your diet is the most efficient way to get the vitamins and minerals you need for balanced hormones, supplements can help close nutritional gaps. Though research is limited, some supplements that may help support healthy T levels include dehydroepiandrosterone (DHEA), zinc, vitamin D, and magnesium. You may also want to try something like Hims Sex Rx + Testosterone Support. This 2-in-1 pill contains tadalafil for longer-lasting, harder erections alongside zinc and L-arginine to support testosterone and blood circulation.
Want to learn more about how to support healthy testosterone levels? Find out if sex increases testosterone, read about the best testosterone boosters for ED, and explore the relationship between anxiety and low testosterone.
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