An Overview of Low Testosterone

The right treatment approach can help you feel well again

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Testosterone levels tend to decline when men reach their 40s. This doesn't always cause noticeable effects, but some men develop symptoms of low testosterone, including decreased libido, weight changes, and sleep problems.

If you have symptoms of low testosterone, you can have your hormone levels measured. Treatment includes hormone replacement and symptomatic therapies. Because testosterone replacement can produce side effects, the decision about this hormone treatment has to be made carefully.


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.

  • 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 mood change associated with decreased testosterone, and you can develop anxiety, irritability, mood swings, nervousness, and an overall lessened sense of well-being as well.
  • 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: The connection between testosterone and sleep seems to be a two-way street. 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.

Complications and Long-Term Effects

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

  • Bone loss: Testosterone can affect bone health, and decreasing levels can lead to osteoporosis in men.
  • Insulin resistance: Over time, insulin resistance results in elevated blood sugar and can lead to type 2 diabetes.
  • 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 a low RBC count and/or low RBC function.

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

  • Hair loss: 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.


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

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.

Low Testosterone in Young Men

There are several medical conditions characterized by diminished testosterone. For example, cancer, chemotherapy 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.

Some antidepressants and steroid hormones may lower testosterone as well. And toxins may reduce testosterone levels through an inflammatory process.

Men who are in their 20s can experience these medical causes of low testosterone and will have the same or even more noticeable symptoms than older men. The long term effects may be more severe when low testosterone lasts for more years. Additionally. low testosterone in young men can contribute to infertility.

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


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 to have testing to help identify other issues, such as high cholesterol and osteoporosis.

Blood Tests

Testosterone can be measured in the blood. A testosterone level of fewer than 300 nanograms per deciliter (ng/dL) is considered low.

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. On the other hand, 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 and the hormone levels all need to be considered together.

Imaging Tests

You may need to have an imaging test such as computerized tomography (CT) scan, magnetic resonance imaging (MRI) test, 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 bone scan can help identify osteoporosis and a blood test can detect high cholesterol levels.


In general, the natural decline in testosterone does not cause noticeable effects until men reach their 70s or 80s. Nevertheless, whether the effects of naturally declining testosterone begin in a man's 40s or 80s, distressing symptoms deserve professional medical attention.

Chronic health conditions may affect testosterone levels, so treatment may involve a combination of lifestyle changes, medical interventions, or testosterone replacement.

Lifestyle Modification

Weight loss 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

If you and your doctor decide that testosterone replacement therapy would be right for you, there are several ways you can take the hormone, including patches, gels, oral tablets, injections, and pellets implanted under the skin.

Conditions such as prostate cancer, elevated prostate markers, or cardiac issues can worsen with testosterone replacement therapy. The treatment also can produce side effects, including prostate or testicular cancer in men who do not have risk factors for these conditions. Testosterone therapy also raises the risk of heart disease and stroke.

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 is normal, yet still causes such distressing effects.

Be sure to discuss your symptoms with your doctor, and 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.

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