Testosterone is the primary sex hormone in men, and it is responsible for the development of many of the physical characteristics that are considered typically male (such as deep voice, hair growth, increased bone density, and many others). Testosterone, part of a hormone class known as androgens, is produced by the testicles after stimulation from the pituitary gland, which is located near the base of the brain, and sends signals to a male's testicles that spark feelings of sexual desire, notes MedlinePlus.

While testosterone may be used to treat women, low levels of testosterone (also known as low T or hypogonadism) is considered a male problem, according to a review published in October 2019 in The Lancet Diabetes and Endocrinology.

Signs and Symptoms of Low Testosterone

Depending on the cause and age when low T first appears, symptoms can differ. Younger males should watch out for:

Underdeveloped genitalia
Delayed puberty onset
Lack of secondary sexual characteristics, like a deeper voice and facial hair

According to the Urology Care Foundation, middle-aged or older men should be aware of:

Fatigue
Depression
Sleep problems
Low sex drive
Inability to get or maintain an erection
Low sperm count
Enlarged or tender breasts
Loss of muscle and bone
Fertility issues
Loss of body hair

Men can have low T but have no symptoms. Also, some symptoms, such as fatigue, sleep problems, and depression, can be due to other issues, such as medication side effects, mental health issues, and abuse of alcohol.

Causes and Risk Factors of Low Testosterone

Men’s testosterone levels start a natural decline starting around age 30, and then drop about 1 percent per year after that for the rest of their lives, according to the Cleveland Clinic.

A variety of other medical conditions can cause significantly lower-than-normal testosterone levels in boys and men. These include:

Autoimmune diseases
Chronic liver or kidney disease
Chronic obstructive lung disease
Genetic causes
Heart failure
HIV or AIDS
Infections (such as mumps)
Injury to the testicles
Metabolic disorders
Obesity
Prolactinoma (prolactin-secreting tumor) or other tumors in the pituitary gland
Testicular cancer or treatment for testicular cancer
Type 2 diabetes

Some drugs are also associated with low testosterone levels, including:

Alcohol
Chemotherapy drugs used to treat cancer
Corticosteroids (sometimes called glucocorticoids)
Opioids

Sometimes the cause of low testosterone in a man is unknown, and many men have several different causes.

How Is Low Testosterone Diagnosed?

Low testosterone is diagnosed with the following tests to check:

Total Testosterone Level
Luteinizing Hormone (LH) Abnormal levels may mean a pituitary gland problem, which can cause low T.
Blood Prolactin Level High levels can also signal pituitary problems or tumors.
Blood hemoglobin (Hgb)

Other possible tests are:

Follicle Stimulating Hormone (FSH) This may be checked for sperm-making function.
Estradiol Hormone Test This is performed if the patient has enlarged breasts.
Glycosylated Hemoglobin (HgbA1C) Blood Test This test looks for diabetes by checking the level of hemoglobin attached to glucose.
Thyroid Hormone Levels Assessing other hormonal abnormalities can contribute to diagnosis.
Cortisol Level This is another potential hormonal abnormality.
Magnetic Resonance Imagine (MRI) An MRI scan of the pituitary gland may be performed.
Bone Density Tests Low T can promote bone loss.
Karyotype (Chromosome Tests)

Prognosis of Low T

The long-term outlook is good, if diagnosed and treated early. Treatment can reverse symptoms, and reduce risk of muscle and bone loss, notes Urology Austin.

Treatment and Medication Options for Low Testosterone

Medication and Nonsurgical Treatment Options

In the past, low T was typically treated with testosterone replacement therapy (TRT). Recently, however, thinking has changed on this. The American College of Physicians updated its clinical practice guidelines to counsel that TRT should only be prescribed to men for sexual dysfunction, according to January 2020 article in the Annals of Internal Medicine.

Possible Side Effects of TRT

Possible long-term effects of TRT have not yet been established, but per the Mayo Clinic, there is scientific evidence to suggest it may cause:

Worse sleep apnea
Acne and other skin irritations
Growth of existing prostate cancer or benign prostate growths
Enlarged breasts
Shrinking testicles and reduced sperm production
Overabundance of red cell production, which can cause blood clots.
Possible cardiovascular complications, including events such as stroke or heart attack

If you do take testosterone for sexual dysfunction, the U.S. Food and Drug Administrations (FDA) says you should seek immediate medical attention if you experiences any symptoms of a heart attack or stroke, such as:

Chest pain
Shortness of breath or trouble breathing
Weakness in one part or side of the body
Slurred speech

Alternative and Complementary Therapies

Lose weight. Losing the pounds often causes testosterone levels to come up, especially if you are obese or have an underlying medical condition such as diabetes that can contribute to low T.
Limit alcohol consumption. Consuming alcohol can convert testosterone to estrogen.
Calm yourself. The stress hormone cortisol can compromise testosterone’s effects.
Get a full night’s sleep. Sleep deprivation shoots up cortisol levels.
Work out. Interval exercise can build muscle mass, which in turn releases testosterone from protein.
Avoid BPA. Drinking out of plastic cups made with the chemical bisphenol A (BPA) can lower testosterone levels.
Get your zinc. Found in shellfish and pork, this mineral can support testosterone levels naturally. If you take a supplement, take 12 to 15 milligrams daily.
Eat healthy fats. Add fats to your diet such as those found in nuts, avocado, and olive oil.
Avoid sugar. This can decrease testosterone.

Prevention of Low Testosterone

As described above, diet, stress management, and several other nonmedical approaches may be effective in staving off low testosterone issues.

Research and Statistics: How Many Men Have Low Testosterone?

In one past study, 1 in 4 men between ages 30 and 79 had total testosterone levels less than 300 nanograms per deciliter (ng/dL), which is generally considered the low end of the normal range.

And there were no differences between men of different races or ethnic groups. Only a minority of men were feeling the sexual effects of low T. Of the men tested, 12 percent reported having low libido and 16 percent had erectile dysfunction.

But the prevalence of symptomatic androgen deficiency — meaning low levels of T that cause discernable health problems — are on the rise, according to the study authors. Other research projected that by the year 2025, as many as 6.5 million American men ages 30 to 79 will have symptomatic androgen deficiency, which is a 38 percent jump from 2000 population estimates.

Resources

Partnership for the Accurate Testing of Hormones (PATH)

PATH formed in 2010 to help the clinical, medical, and public health communities improve patient care through more accurate and reliable hormone tests. PATH supports research that improves the diagnosis and treatment of hormone disorders, including a landmark 2017 study that defines the “normal” range of testosterone in young adult men.

Dr. Turek’s Blog, The Turek Clinic

Paul Turek, MD, a urologist in San Francisco, is an international leader in male fertility research. He blogs about men’s health topics, including steroids, testosterone, and male infertility, on the Turek Clinic’s website.

Clinical Trials

If you would like to know more about testosterone clinical trials, check ClinicalTrials.gov.

Editorial Sources and Fact-Checking

References

Testosterone. MedlinePlus. June 4, 2018.
Low Testosterone — Symptoms. The Urology Care Foundation. July 2020.
Low Testosterone: Male Hypogonadism. Cleveland Clinic Today. April 10, 2018.
What Is Low Testosterone? Urology Care Foundation. July 2020.
Low Testosterone Consultation Information. Urology Austin. May 2018.
Sexual Health. Mayo Clinic. April 4, 2020.
7. FDA Drug Safety Communication: FDA Cautions About Using Testosterone Products for Low Testosterone Due to Aging; Requires Labeling Change to Inform of Possible Increased Risk of Heart Attack and Stroke With Use. U.S. Food and Drug Administration. February 26, 2018.
Araujo AB, Esche GR, Kupelian V, et al. Prevalence of Symptomatic Androgen Deficiency in Men. The Journal of Clinical Endocrinology and Metabolism. November 2007.
Kumar P, Kumar N, Thakur DS, Patidar A. Male Hypogonadism: Symptoms and Treatment. Journal of Advanced Pharmaceutical Technology and Research. July–September 2010.
Qaseem A, Horwitch C, Vijan S, et al. Testosterone Treatment in Adult Men With Age-Related Low Testosterone: A Clinical Guideline From the American College of Physicians Annals of Internal Medicine. January 21, 2020.
Islam RM, Bell RJ, Green S, et al. The Lancet Diabetes and Endocrinology. July 25, 2019

Sources

Low Testosterone (Hypogonadism). Hormone Health Network. April 2020.

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What Is Low Testosterone? Symptoms, Causes, Diagnosis, Treatment, and Prevention