Low Testosterone: Symptoms, Causes & Treatment

What Is Low Testosterone?

Low testosterone (hypogonadism) is a condition where the body doesn't produce enough testosterone, the primary male sex hormone. It affects approximately 2-6% of men aged 40-79 and can cause symptoms ranging from reduced libido and erectile dysfunction to fatigue, mood changes, and loss of muscle mass.

Testosterone is a hormone that plays a fundamental role in male development and health throughout life. It is produced primarily in the testicles and is responsible for the development of male sexual characteristics during puberty, including the growth of the penis and testicles, deepening of the voice, and growth of body and facial hair. Beyond puberty, testosterone remains essential for maintaining muscle mass, bone density, red blood cell production, fat distribution, and sexual function.

The term "hypogonadism" refers to a condition where the gonads (testicles in men) produce insufficient amounts of sex hormones. When testosterone levels fall below the normal range and cause noticeable symptoms, doctors may diagnose low testosterone or testosterone deficiency syndrome. This condition can occur at any age, though it becomes more common with advancing age due to the natural decline in testosterone production that begins around age 30-40.

It's important to understand that testosterone levels naturally vary throughout the day, with the highest levels typically occurring in the morning. This is why diagnostic blood tests should be performed in the morning, usually between 7-10 AM, to get the most accurate measurement. A single low reading is not sufficient for diagnosis; at least two separate low readings taken on different days are typically required to confirm testosterone deficiency.

Normal testosterone levels

Normal testosterone levels can vary somewhat depending on the laboratory and the specific testing method used. However, most medical guidelines define low testosterone as a total testosterone level below 300 ng/dL (10.4 nmol/L). The normal range is generally considered to be between 300-1000 ng/dL (10.4-34.7 nmol/L), though optimal levels may vary between individuals based on their age, health status, and personal symptoms.

Free testosterone, which is the portion not bound to proteins and therefore biologically active, represents only about 2-3% of total testosterone. Some men with total testosterone in the low-normal range may still have symptoms if their free testosterone is low. This is why comprehensive evaluation often includes both total and free testosterone measurements.

What Are the Symptoms of Low Testosterone?

The main symptoms of low testosterone include reduced sex drive (libido), difficulty getting or maintaining erections, fatigue that doesn't improve with rest, mood changes including depression and irritability, decreased muscle mass, increased body fat (especially around the abdomen), and difficulty concentrating. Symptoms typically develop gradually over months to years.

Low testosterone can affect virtually every system in the body, leading to a wide range of symptoms that may develop so gradually that men don't initially recognize them as related to a hormonal problem. Many men attribute these changes to "normal aging" or stress, delaying evaluation and treatment. Understanding the full spectrum of symptoms is important for early recognition and appropriate medical care.

The symptoms of testosterone deficiency can be broadly categorized into sexual symptoms, physical symptoms, and psychological symptoms. While any of these can occur in isolation, most men with significantly low testosterone experience symptoms across multiple categories. The severity of symptoms often correlates with how low testosterone levels are and how quickly they declined.

Sexual symptoms

Sexual symptoms are often the most noticeable and concerning for men with low testosterone. Reduced libido, or decreased interest in sex, is one of the earliest and most common symptoms. This goes beyond the normal fluctuations in desire that everyone experiences and represents a persistent, noticeable decline in sexual interest that may affect relationships and quality of life.

Erectile dysfunction is another common symptom, though it's important to note that erectile problems can have many causes beyond low testosterone, including cardiovascular disease, diabetes, and psychological factors. Men with low testosterone may find it difficult to achieve erections or may notice that their erections are not as firm or long-lasting as before. Some men also experience reduced spontaneous erections, such as morning erections.

• Reduced libido: Decreased interest in sexual activity
• Erectile dysfunction: Difficulty achieving or maintaining erections
• Reduced spontaneous erections: Fewer morning erections
• Reduced ejaculate volume: Less semen production
• Infertility: Decreased sperm production

Physical symptoms

Physical changes associated with low testosterone include decreased muscle mass and strength, even with regular exercise. Many men notice that their workouts become less effective and that they recover more slowly from physical activity. At the same time, body fat may increase, particularly around the abdomen, despite no changes in diet or activity level.

Other physical symptoms include reduced body and facial hair growth, breast enlargement (gynecomastia), and decreased bone density (osteoporosis), which increases the risk of fractures. Some men experience hot flashes similar to those women experience during menopause. Fatigue and decreased energy are extremely common and often among the most bothersome symptoms.

Psychological and cognitive symptoms

Low testosterone significantly impacts mood and cognitive function. Depression, irritability, and mood swings are common, and some men report a general sense of decreased well-being or loss of motivation. These symptoms can be difficult to distinguish from other causes of depression and may be overlooked or misdiagnosed.

Cognitive symptoms include difficulty concentrating, poor memory, and reduced mental clarity often described as "brain fog." Sleep disturbances are also common, including insomnia and changes in sleep patterns. Paradoxically, while fatigue is a hallmark symptom, some men also experience restlessness and difficulty sleeping.

What Causes Low Testosterone?

Low testosterone can be caused by aging (levels decline 1-2% per year after 40), medical conditions including type 2 diabetes, obesity, pituitary disorders, and testicular problems, medications such as opioids and chemotherapy, and lifestyle factors including chronic stress, poor sleep, and excessive alcohol use.

Understanding the causes of low testosterone is essential for proper diagnosis and treatment. Doctors classify hypogonadism into two main categories based on where the problem originates: primary hypogonadism (when the problem is in the testicles) and secondary hypogonadism (when the problem is in the pituitary gland or hypothalamus in the brain, which control testicular function). Some men have mixed or combined hypogonadism with problems at multiple levels.

The distinction between primary and secondary hypogonadism is clinically important because it guides both diagnostic testing and treatment decisions. Blood tests measuring luteinizing hormone (LH) and follicle-stimulating hormone (FSH) help determine the cause. In primary hypogonadism, LH and FSH are elevated as the pituitary tries to stimulate the failing testicles. In secondary hypogonadism, these hormones are low or inappropriately normal despite low testosterone.

Age-related decline

Testosterone levels naturally begin to decline around age 30-40 at a rate of approximately 1-2% per year. This gradual decline is sometimes called "andropause" or "late-onset hypogonadism," though unlike female menopause, it is gradual rather than abrupt. By age 70, many men have testosterone levels 30-50% lower than in their 20s.

However, it's important to emphasize that age-related testosterone decline doesn't necessarily mean every older man will develop symptoms requiring treatment. Many men maintain adequate testosterone levels and function well into old age. Whether age-related decline requires treatment depends on symptoms and individual circumstances rather than age alone.

Medical conditions

Numerous medical conditions can cause or contribute to low testosterone. Type 2 diabetes is particularly strongly associated, with studies showing that 30-50% of men with type 2 diabetes have low testosterone. The relationship appears to be bidirectional: diabetes contributes to low testosterone, and low testosterone increases the risk of developing diabetes.

Other medical conditions associated with low testosterone include:

• Obesity: Fat tissue contains enzymes that convert testosterone to estrogen, reducing testosterone levels significantly
• Pituitary disorders: Tumors or other problems affecting the pituitary gland can reduce hormone signals to the testicles
• Hypothyroidism: Underactive thyroid can affect testosterone production
• Kidney disease: Chronic kidney failure affects hormone metabolism
• Testicular disorders: Inflammation, injury, or tumors affecting the testicles
• Klinefelter syndrome: A genetic condition affecting approximately 1 in 500-1000 males
• HIV/AIDS: Both the virus and some treatments can affect testosterone

Medications and treatments

Several medications can reduce testosterone levels as a side effect. Opioid pain medications are particularly problematic, with studies showing that up to 90% of men on long-term opioid therapy develop low testosterone. Corticosteroids (prednisone and similar medications) can also suppress testosterone production when used long-term.

Cancer treatments, including chemotherapy and radiation therapy (especially to the pelvic area or testicles), can damage the testicles and reduce testosterone production. In some cases, this damage may be permanent. Surgical removal of one or both testicles for testicular cancer obviously affects testosterone production significantly.

Lifestyle factors

Lifestyle factors play an increasingly recognized role in testosterone levels. Chronic sleep deprivation has been shown to significantly reduce testosterone, with one study finding that young men who slept only 5 hours per night for one week had testosterone levels 10-15% lower than normal. Chronic stress, through elevated cortisol levels, can also suppress testosterone production.

Excessive alcohol consumption damages the testicles and interferes with testosterone production. Alcohol abuse is also associated with liver damage, which can further disrupt hormone metabolism. Drug abuse, particularly of opioids but also of marijuana and other substances, can significantly reduce testosterone levels.

When Should You See a Doctor About Low Testosterone?

See a doctor if you experience persistent symptoms such as reduced sex drive that doesn't improve, recurring erectile dysfunction, unexplained fatigue, mood changes including depression or irritability, or loss of muscle mass despite exercise. You should also be evaluated if you have conditions associated with low testosterone such as type 2 diabetes or obesity.

Many men hesitate to discuss symptoms of low testosterone with their doctors, whether due to embarrassment, belief that symptoms are just "normal aging," or uncertainty about whether their symptoms warrant medical attention. However, early evaluation is important because low testosterone is associated with increased risks of osteoporosis, metabolic syndrome, and potentially cardiovascular disease.

Consider scheduling an appointment with your doctor if you experience any of the following:

• Reduced interest in sex that persists and affects your relationship or quality of life
• Recurring difficulty achieving or maintaining erections
• Loss of morning erections that you previously had regularly
• Unusual fatigue that doesn't improve with adequate rest
• Unexplained mood changes, depression, or irritability
• Night sweats or hot flashes
• Difficulty building or maintaining muscle despite regular exercise
• Unexplained weight gain, particularly around the midsection

How Is Low Testosterone Diagnosed?

Low testosterone is diagnosed through morning blood tests measuring total testosterone (and often free testosterone), with at least two separate low readings required for diagnosis. Additional tests including LH, FSH, prolactin, and thyroid function help determine the cause. A physical examination and assessment of symptoms are also essential components of diagnosis.

Diagnosing low testosterone involves more than just a blood test. A comprehensive evaluation should include a thorough medical history, physical examination, and appropriate laboratory testing. Your doctor will want to understand your symptoms, their duration and severity, your medical history, medications, and lifestyle factors that might contribute to low testosterone.

The physical examination typically includes assessment of body composition (muscle mass and fat distribution), examination of the testicles for size and any abnormalities, checking for breast enlargement (gynecomastia), and evaluation of body hair distribution. Your doctor may also assess bone density if osteoporosis is a concern.

Blood tests for testosterone

The primary diagnostic test is measurement of total testosterone in the blood. Because testosterone levels fluctuate throughout the day and are highest in the morning, blood should be drawn between 7-10 AM for the most accurate results. At least two separate morning blood tests showing low testosterone are typically required to confirm the diagnosis.

Most guidelines define low testosterone as a total testosterone level below 300 ng/dL (10.4 nmol/L), though some experts use slightly different cutoffs. If total testosterone is borderline (300-400 ng/dL), measurement of free testosterone may be helpful, as this represents the biologically active fraction not bound to proteins in the blood.

Additional diagnostic tests

Additional blood tests help determine the cause of low testosterone and rule out other conditions. These typically include:

• LH and FSH: Help distinguish between primary and secondary hypogonadism
• Prolactin: Elevated levels can suppress testosterone and may indicate a pituitary tumor
• Thyroid function tests: Thyroid disorders can affect testosterone
• Complete blood count: Testosterone affects red blood cell production
• PSA (prostate-specific antigen): Baseline measurement before starting testosterone therapy
• Metabolic panel: To assess overall health and liver/kidney function

In some cases, additional testing may be necessary. If a pituitary problem is suspected, MRI of the brain may be ordered to look for tumors or other abnormalities. Semen analysis may be performed if fertility is a concern. Bone density testing (DEXA scan) may be recommended to assess for osteoporosis.

How Is Low Testosterone Treated?

Low testosterone is treated with testosterone replacement therapy (TRT), which can be administered as topical gels applied daily, intramuscular injections every 1-2 weeks, or other formulations. Treatment is effective for improving symptoms when properly indicated and monitored. Regular blood tests are required to monitor testosterone levels and watch for side effects.

The decision to treat low testosterone should be based on both confirmed low testosterone levels (documented by at least two morning blood tests) and the presence of significant symptoms. Testosterone replacement therapy is not recommended for men with normal testosterone levels or for those with low testosterone but no symptoms. Treatment goals include alleviating symptoms, improving quality of life, and preventing complications of testosterone deficiency.

Before starting treatment, your doctor should discuss the potential benefits and risks, ensure you understand the commitment to ongoing therapy and monitoring, and rule out any contraindications. Men with certain conditions, such as prostate cancer, breast cancer, severe heart failure, or untreated severe sleep apnea, should generally not receive testosterone therapy.

Types of testosterone replacement therapy

Testosterone replacement therapy is available in several formulations, each with advantages and disadvantages. The choice depends on individual preferences, lifestyle factors, cost considerations, and how well you respond to different forms of treatment.

Topical testosterone gel is one of the most commonly prescribed forms. Applied daily to the shoulders, upper arms, or abdomen, it provides relatively steady testosterone levels. Brands include AndroGel and Testogel. The gel is convenient but requires care to avoid transferring testosterone to others through skin contact, particularly women and children.

Intramuscular injections of testosterone cypionate or testosterone enanthate are typically given every 1-2 weeks. This method is effective and often less expensive than gels, but testosterone levels fluctuate more, with higher levels shortly after injection and lower levels just before the next dose. Some men notice mood or energy fluctuations corresponding to this cycle.

Other options include testosterone patches (applied daily), testosterone pellets (implanted under the skin every 3-6 months), and nasal testosterone gel (applied inside the nose 2-3 times daily). Each has specific advantages for certain patients.

Expected benefits of treatment

With proper testosterone replacement therapy, most men experience improvement in their symptoms over time. Sexual function, including libido and erectile function, typically improves within 3-6 weeks of starting treatment. Energy levels and mood often improve within this timeframe as well.

Changes in body composition take longer. Increases in muscle mass and strength and decreases in fat mass typically become noticeable after 3-6 months of treatment. Improvements in bone density require 6-12 months or longer and are typically assessed with repeat bone density testing.

Monitoring during treatment

Regular monitoring is essential during testosterone replacement therapy. Blood tests to check testosterone levels, hematocrit (red blood cell count), and PSA are typically performed 3-6 months after starting therapy and at least annually thereafter. The goal is to maintain testosterone levels in the mid-normal range and to detect any adverse effects early.

Potential side effects and risks

Like all medications, testosterone replacement therapy has potential side effects. Common side effects include acne, oily skin, and increased body hair. More significant concerns include:

• Increased red blood cell count (polycythemia): Can increase the risk of blood clots if levels become too high
• Worsening of sleep apnea: Testosterone can exacerbate obstructive sleep apnea
• Reduced sperm production: TRT suppresses natural testosterone and sperm production, potentially causing infertility
• Prostate effects: May cause prostate enlargement or worsen existing prostate conditions
• Cardiovascular effects: The relationship between TRT and cardiovascular disease remains under study

When testosterone therapy is not appropriate

If your symptoms are caused by factors other than low testosterone, testosterone replacement therapy will not help. In such cases, your doctor may recommend other treatments. For example, if you have erectile dysfunction with normal testosterone levels, medications like sildenafil (Viagra) or tadalafil (Cialis) may be appropriate.

Similarly, if low testosterone is caused by obesity, weight loss may be the most appropriate first-line treatment. Studies have shown that significant weight loss can substantially increase testosterone levels in obese men, sometimes normalizing levels without the need for hormone replacement.

What Can You Do Yourself to Improve Testosterone Levels?

Lifestyle modifications that can help improve testosterone levels include losing excess weight, engaging in regular exercise (especially resistance training), getting adequate sleep (7-9 hours per night), managing stress, limiting alcohol consumption, and ensuring adequate intake of zinc and vitamin D through diet or supplements.

While testosterone replacement therapy is effective for men with diagnosed hypogonadism, lifestyle modifications are an important first-line approach, particularly for men with borderline-low testosterone or those with modifiable risk factors. For men with obesity-related low testosterone, lifestyle changes may normalize levels without the need for medication.

Weight management

Obesity is one of the strongest modifiable risk factors for low testosterone. Fat tissue contains the enzyme aromatase, which converts testosterone to estrogen. The more body fat you have, the more of your testosterone gets converted to estrogen, and the lower your testosterone levels become. This creates a vicious cycle, as low testosterone promotes fat accumulation while excess fat further lowers testosterone.

Studies have demonstrated that weight loss can significantly increase testosterone levels. In one study, obese men who lost an average of 17 kg through diet and exercise saw their testosterone levels increase by an average of 2.9 nmol/L. Bariatric surgery in severely obese men can lead to even more dramatic improvements in testosterone levels.

Exercise

Regular physical activity, particularly resistance training (weightlifting), can help optimize testosterone levels. While a single exercise session can temporarily boost testosterone, the long-term benefits come from regular, consistent training. Both resistance training and high-intensity interval training (HIIT) appear to be particularly effective.

However, it's important to avoid overtraining, which can actually suppress testosterone levels. Adequate rest and recovery between workouts are essential. Working with a qualified fitness professional can help you develop an appropriate exercise program.

Sleep

Sleep is crucial for testosterone production, as most testosterone is produced during sleep. Studies have shown that restricting sleep to 5 hours per night for just one week can reduce testosterone levels by 10-15%. Aim for 7-9 hours of quality sleep per night, and address any sleep disorders such as sleep apnea that may be interfering with your sleep.

Stress management

Chronic stress increases cortisol levels, and elevated cortisol suppresses testosterone production. While it's impossible to eliminate stress entirely, developing effective stress management strategies can help. This might include mindfulness meditation, yoga, regular exercise, adequate leisure time, and maintaining social connections.

Nutrition

Certain nutrients are important for testosterone production. Zinc is essential, and deficiency has been linked to low testosterone. Good sources include oysters, beef, crab, and fortified cereals. Vitamin D also appears to play a role, with studies suggesting that men with adequate vitamin D levels tend to have higher testosterone levels.

A balanced diet with adequate protein, healthy fats, and complex carbohydrates supports overall hormonal health. Avoid excessive alcohol, which can damage the testicles and suppress testosterone production. Moderate alcohol consumption (up to 1-2 drinks per day) appears to have minimal impact on testosterone.

What Happens in the Body with Low Testosterone?

Testosterone is produced primarily in the testicles under the control of the pituitary gland. It binds to androgen receptors throughout the body, affecting sexual function, muscle and bone development, fat distribution, red blood cell production, and brain function. Low testosterone disrupts these processes, leading to the characteristic symptoms of deficiency.

Understanding how testosterone works in the body helps explain why low levels cause such wide-ranging symptoms. Testosterone is the primary male sex hormone, though both men and women produce it (women in much smaller amounts). In men, about 95% of testosterone is produced in the Leydig cells of the testicles, with the remaining 5% coming from the adrenal glands.

Regulation of testosterone production

Testosterone production is controlled by a complex feedback system involving the hypothalamus and pituitary gland in the brain. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which signals the pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH travels through the bloodstream to the testicles, where it stimulates the Leydig cells to produce testosterone.

When testosterone levels are adequate, they send feedback signals to the hypothalamus and pituitary to reduce GnRH and LH production. This feedback loop keeps testosterone levels within a normal range. When this system is disrupted at any level—hypothalamus, pituitary, or testicles—low testosterone can result.

Effects throughout the body

Testosterone circulates in the blood and affects virtually every organ system. In boys and young men, it is essential for the development of male sexual characteristics during puberty, including genital development, voice deepening, and the growth of body and facial hair. In adult men, testosterone maintains these characteristics and supports ongoing physiological functions.

Key effects of testosterone include:

• Sexual function: Essential for libido and erectile function
• Muscle: Promotes protein synthesis and muscle growth
• Bone: Stimulates bone formation and maintains bone density
• Fat metabolism: Influences fat distribution and metabolism
• Red blood cells: Stimulates erythropoietin production, which increases red blood cell count
• Brain: Affects mood, cognition, and sense of well-being
• Sperm production: High testosterone levels within the testicles are needed for sperm production

When testosterone levels fall below normal, all of these processes can be affected, leading to the diverse symptoms characteristic of testosterone deficiency. Understanding this helps explain why treatment with testosterone replacement can improve symptoms across multiple body systems.