What Is Low Testosterone?

The right treatment approach can help you feel well again

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Testosterone levels start to decline when men reach age 30, although low testosterone (a.k.a. low T) can also be caused by a medical issue. This doesn't always cause noticeable effects, but some men develop symptoms of low testosterone, including decreased libido, weight changes, and sleep problems. Hormone levels can be tested to confirm low testosterone, and certain regimens including hormone replacement and symptomatic therapies are available.

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Low Testosterone Symptoms

There are a number of symptoms and long-term effects of low testosterone. They can develop gradually, but you might suddenly notice them when they start to interfere with your daily life. In fact, a natural decline (1%) in testosterone usually does not cause noticeable effects until men reach their 70s or 80s. For many reasons, however, these may occur earlier.

Symptoms and signs of low testosterone can include:

  • Fatigue: Many men feel less energetic or need to take more naps as they get older. While there are several potential causes for this problem, decreased testosterone is often one of them.
  • Mood changes: Depression is the most common one, but you can develop anxiety, irritability, mood swings, nervousness, and an overall lessened sense of well-being.
  • Physical changes: Low testosterone causes a gradual loss of muscle mass and increased body fat.
  • Erectile dysfunction and low libido: Sufficient levels of testosterone are required for an erection. While sex drive naturally declines with age, you should talk to your doctor if you experience erectile dysfunction or a significant loss of libido.
  • Disordered sleep: Not only can low testosterone interfere with your sleep, but a lack of sleep can also reduce your levels of testosterone.
  • Diminished cognitive skills: Low testosterone levels can interfere with a man's memory, concentration, and problem-solving abilities.

Many of the effects of low testosterone can worsen each other. For example, fatigue can disrupt mood, sleep, and libido.

Male pattern baldness is caused by testosterone. After years of testosterone exposure, men begin to lose their hair. However, it isn't high or low testosterone that regulates hair loss—the extent and pattern of a man's hair loss is primarily genetic.

Complications and Long-Term Effects

In addition to the symptoms of low testosterone, you may also have some effects that are not necessarily obvious to you, yet have consequences for your overall health.

  • Bone loss: Testosterone can affect bone health and decreasing levels can lead to osteopenia or osteoporosis in men. A bone scan (called a DEXA scan) can be done to assess bone density in men with low testosterone
  • Insulin resistance: Over time, insulin resistance results in elevated blood sugar and can lead to type 2 diabetes. Having diabetes can lead to low testosterone.
  • Elevated cholesterol: High cholesterol is a risk factor for heart disease and stroke.
  • Anemia: Testosterone helps the body make red blood cells (RBCs), and low testosterone can result in anemia—which is low RBC count and/or low RBC function.

Low testosterone in young men can also contribute to infertility, since testosterone is needed for sperm production. This should not be confused with the issue that testosterone replacement may cause; the majority of testosterone products available can lower sperm production. Specialized medications from a male reproductive specialist are needed to both raise testosterone and improve/maintain sperm production.

The long-term effects may be more severe the longer low testosterone levels persist.


Testosterone is a steroid hormone produced by the testicles and adrenal glands. It mediates male sexual development during childhood and puberty, regulating sperm production, libido, male voice development, and body and facial hair growth. Testosterone also aids in metabolism, bone formation, muscle development, and red blood cell production.

Testosterone levels tend to reach their peak in early adulthood and start dropping when men are in their 40s by about 1% to 2% each year. This is not an abnormality or an illness, and it is caused by a natural decrease in testosterone production in the body.

There are cases of low testosterone that are not normal and are due to medical concerns, however.

Congenital Conditions

A number of congenital conditions such as Noonan syndrome and Klinefelter syndrome are characterized by low testosterone during childhood.

These conditions interfere with male sexual development. Young men who have these conditions may have small testicles, a lack of body hair, a high voice, obesity, and cognitive problems. Issues with infertility are usually a problem as well.

Hypogonadism, which is a decreased development of male sexual organs, is an effect of low testosterone at an early age.

Diseases and Treatments

There are several medical conditions characterized by diminished testosterone. For example, cancer (and chemotherapy used to treat it) or a pituitary tumor can result in hormonal imbalances that include low testosterone levels. And diabetes and obesity increase the risk of low testosterone during adulthood.

Many other chronic inflammatory conditions may be associated with low testosterone. Some antidepressants and steroid hormones may lower testosterone as well. Opioid narcotics may also reduce testosterone.

Some antidepressants and steroid hormones may lower testosterone as well. And toxin exposure may reduce testosterone levels by triggering an inflammatory process.

The medical causes of low testosterone are more likely to affect boys and men under age 40. And young men who have a medical cause of low testosterone (as opposed to a natural age-related decline in testosterone) will experience more noticeable symptoms because they are at an age when they need higher amounts of testosterone than older men do.


Diagnosis of low testosterone often requires blood tests that measure testosterone and other hormones. Imaging studies can help identify a tumor.

Additionally, you may need testing to help identify complications of low T, such as high cholesterol and osteoporosis.

Blood Tests

Testosterone can be measured in the blood. A testosterone level of less than 300 to 350 nanograms per deciliter (ng/dL) is considered low. A testosterone level of less than 300 nanograms per deciliter (ng/dL) is considered low if completed on two occasions in the morning.

Other hormones, including luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and prolactin can be measured as well. LH, FSH, and estradiol help regulate testosterone; prolactin level is often a reflection of pituitary function.

Sometimes, low levels of these regulatory hormones help point to the cause of low testosterone. However, hormones that stimulate the production of testosterone can be elevated as the body attempts to compensate for low testosterone.

Interpretation of hormone level results is not straightforward. All results must be considered together, rather than individually.


You may need to have an imaging test such as computerized tomography (CT), magnetic resonance imaging (MRI), or ultrasound to evaluate the cause of your low testosterone, especially if it does not seem to be related to a natural decline.

Testicular disease can be evaluated with an imaging test of the pelvis, adrenal gland disease with an abdominal CT scan, and pituitary or hypothalamic disease with a brain MRI.

Testing for Complications

If you have been diagnosed with low testosterone, you may need additional testing to identify the signs of complications. Testing depends on your symptoms, but if you have had low testosterone for years, then you may need a screening test.

For example, a DEXA bone density test can help identify osteoporosis and a blood test can detect high cholesterol levels.


Whether the effects of naturally declining testosterone announce themselves in a man's 40s or 80s, distressing symptoms deserve professional medical attention.

One important reason for this is that, if a disease or condition is what's resulting in low testosterone, it most often needs to be addressed to prevent complications related to that primary cause. In doing so, low testosterone symptoms can be improved and levels corrected. This may involve a combination of lifestyle changes and medical interventions.

Testosterone replacement might be beneficial when it comes to alleviating effects of low testosterone, but replacement isn't always necessary if the hormone level is only minimally affected or if it isn't causing symptoms.

Furthermore, hormone replacement isn't safe for everyone, so you and your doctor may opt to forego this treatment to avoid medical complications.

Lifestyle Modifications

Maintaining a healthy weight through exercise and a balanced diet is the most effective lifestyle modification for the management of low testosterone.

Because inflammation and toxin exposure may reduce testosterone levels, avoiding pesticides and other chemicals may be beneficial as well.

Testosterone Replacement

Testosterone replacement can help restore your testosterone levels and, therefore, reduce symptoms. But it's not without risks. For those interested in fertility, this should be discussed with a physician prior to testosterone replacement. There are specific medications that maintain or improve fertility while also raising testosterone. Many common testosterone medications, including topical and injectables, lower fertility or can even cause no sperm (azoospermia).

There is some controversy regarding effects of testosterone replacement in men with risk for or history of prostate cancer or older men with cardiac or stroke history, so it is best to review this carefully with your physicians before starting any regimen.

Keep in mind that if you decide to hold off on using testosterone replacement, you can start it later. Similarly, you and your doctor can decide to stop the medication if you experience side effects.

Men who are not deficient in testosterone should not use testosterone replacement or any supplements that are touted as testosterone replacements, as they can cause serious side effects.

A Word From Verywell

You may be surprised to learn that some symptoms you are experiencing could be related to low testosterone. And it can be confusing to learn that low testosterone can be normal, yet still cause such distressing effects. Discuss your symptoms with your doctor so you can not only determine the best course for getting back to feeling your best, but rule out any medical concerns that could be affecting your hormone levels.

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