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What causes a man’s testosterone level to drop?

Testosterone is the primary male sex hormone and is responsible for the development of male characteristics and reproductive function. As men age, their testosterone levels naturally decline by approximately 1-2% per year after age 30. While testosterone reduction is a normal part of aging, some men can experience a more significant drop in testosterone levels that leads to troublesome symptoms. Understanding the potential causes of low testosterone can help men identify ways to maintain healthy levels as they get older.

What is considered a low testosterone level?

Testosterone levels vary widely between men. In general, a testosterone level between 300 to 1,000 ng/dL is considered normal for adult males. A testosterone level below 300 ng/dL is considered low and may cause symptoms like low libido, erectile dysfunction, decreased muscle mass, increased body fat, low energy, and mood disturbances.

Some potential reference ranges for testosterone levels include:

– Ages 19-39: 240-950 ng/dL
– Ages 40-59: 240-840 ng/dL
– Over age 60: 240-730 ng/dL

However, there is no consensus on precise testosterone level cutoffs, as levels can fluctuate daily and be affected by many factors. The symptoms present are often more telling than a single testosterone reading when evaluating testosterone deficiency.

What factors influence testosterone levels?

Many different factors can impact testosterone production and levels in men, including:

Aging: Testosterone levels peak during adolescence and early adulthood. After age 30, they decline about 1% per year.

Genetics: Gene mutations like Klinefelter syndrome can affect testosterone.

Obesity: Increase in body fat can lower testosterone.

Sleep: Poor sleep and sleep apnea can reduce testosterone.

Stress: High stress and cortisol levels can suppress testosterone.

Smoking and alcohol: Smoking and heavy alcohol use can lower testosterone.

Chronic Illness: Conditions like diabetes, cancer, renal failure, liver disease, and HIV/AIDS are associated with low testosterone.

Medications: Opioid pain medicines, steroids, and some blood pressure drugs can lower testosterone.

Head injuries/trauma: Injuries to the brain, testes, or pituitary gland can affect testosterone production.

Major causes of low testosterone

Some of the most common potential causes for clinically low testosterone levels in men include:

Primary hypogonadism

Primary hypogonadism occurs when there is a problem with the testes’ ability to produce testosterone. Potential causes include:

– Undescended testicles
– Infection or inflammation
– Testicular cancer or injury
– Klinefelter syndrome
– Hemochromatosis
– Radiation/chemotherapy
– Alcoholism
– Very old age

In primary hypogonadism, the problem lies in the testes themselves. The pituitary gland and hypothalamus are still signaling the testes to produce testosterone normally, but the testes are unable to respond appropriately.

Secondary hypogonadism

Secondary hypogonadism is caused by a problem with the pituitary gland or hypothalamus, which signal the testes to produce testosterone. Potential causes include:

– Pituitary tumors, inflammation, or injury
– Medications – steroids, opioid pain medicines
– Obesity
– Neurologic conditions
– Genetic disorders
– Radiation

In secondary hypogonadism, the testes themselves are still functionally normal, but they are not receiving the proper signals from the brain to produce adequate testosterone. Treating the underlying problem causing hypothalamic/pituitary dysfunction may help restore normal testosterone levels.


Obesity drives down testosterone levels through multiple mechanisms, especially in men with excess abdominal fat. Potential reasons obesity may lower testosterone include:

– Increased conversion of testosterone to estrogen in fat cells
– Impaired stimulation of testosterone from luteinizing hormone
– Leptin and pro-inflammatory cytokine resistance
– Insulin resistance and type 2 diabetes

Weight loss has been shown to help reverse low testosterone in obese men. Even losing a modest amount of weight can help restore healthy testosterone levels.

Metabolic syndrome

Metabolic syndrome refers to a cluster of conditions including increased blood sugar, excess body fat around the waist, abnormal cholesterol levels, and high blood pressure. Metabolic syndrome doubles the risk of low testosterone. Insulin resistance, inflammation, and obesity likely contribute to lower testosterone levels in men with metabolic syndrome. Treating the components of metabolic syndrome may help alleviate low testosterone.

Type 2 diabetes

About 50% of men with type 2 diabetes have been found to have low testosterone levels. The reasons for this strong association are not entirely clear but likely involve impaired testosterone production due to insulin resistance, inflammation, weight gain, and possibly medications used to treat diabetes. Getting blood sugar under control and losing weight tends to increase testosterone levels in men with type 2 diabetes.

Sleep disorders

Sleep disorders like obstructive sleep apnea have been associated with decreased testosterone levels. During sleep apnea episodes, oxygen levels drop and inflammation increases, which may impair testosterone production. CPAP therapy for sleep apnea has been shown to help normalize testosterone levels, especially when combined with weight loss in obese men.


Up to 50% of men with HIV/AIDS have been found to have low testosterone. Contributing factors likely include weight loss, opportunistic infections, inflammation, radiation, chemotherapy, and medications used to treat HIV and AIDS. Treatment with testosterone therapy may help offset symptoms of testosterone deficiency in this population once the underlying infection is controlled.


Several types of prescription medications have been associated with lower testosterone levels, including:

– Corticosteroids – often prescribed for inflammatory conditions.
– Opiates – used for pain management.
– Anti-seizure drugs.
– Androgen or estrogen therapy – can inhibit natural testosterone production via feedback inhibition.

If possible, discontinuing or changing medications may help restore normal testosterone levels.

Aging and late-onset hypogonadism

As men get older, testosterone levels gradually decline. After age 60, around 20% of men experience late-onset hypogonadism. Contributing factors include accumulating medical conditions, medications, and body composition changes that occur with aging. Determining if an older man has clinically significant symptoms of low testosterone is important to guide treatment decisions.

Symptoms and health risks

The symptoms of low testosterone that men may experience include:

– Low libido and erectile dysfunction
– Reduced muscle mass and strength
– Increased body fat and reduced lean body mass
– Thinning bones (osteoporosis)
– Depressed mood and reduced motivation
– Irritability and impaired cognition
– Fatigue and low energy
– Hot flashes and night sweats
– Breast enlargement (gynecomastia)

If left untreated, clinically low testosterone levels can lead to:

– Increased risk of cardiovascular disease
– Loss of bone mineral density (osteoporosis)
– Cognitive impairment and increased risk of Alzheimer’s disease
– Decreased quality of life
– Premature death

However, research on the effects of testosterone therapy in older men has had conflicting results. The risks and benefits of treating age-related testosterone decline are still not fully clear.


Diagnosing low testosterone involves both measuring testosterone blood levels and evaluating symptoms. Due to normal daily fluctuations in levels, at least two early morning blood samples are recommended for testing. Diagnosis should only be made if BOTH:

1) Blood testosterone concentration is below the normal range
2) Symptoms of low testosterone are present

If a man has low levels but few or no symptoms, treatment is not necessarily recommended.


Treatment for clinically low testosterone may include:

– Testosterone replacement therapy – Available as injections, gels, patches, and pellets implanted under the skin.
– Addressing underlying health conditions – Such as obesity, diabetes, and pituitary disorders.
– Changing medications – If possible, discontinuing drugs that lower testosterone.
– Lifestyle changes – Losing weight, improving sleep, reducing stress and alcohol intake, and increasing exercise.

The benefits and risks of long-term testosterone therapy are still under study. Treatment is generally recommended for symptomatic men under age 65 with very low testosterone levels. Careful monitoring and adjustment of therapy to maintain testosterone levels in the mid-normal range are important to minimize potential adverse effects on the prostate and heart.

Preventing testosterone decline

While some decline in testosterone levels is inevitable as men age, certain lifestyle habits and health conditions can hasten this drop. Some ways men can help maintain healthy testosterone levels include:

– Achieving and maintaining a healthy weight
– Engaging in regular exercise and strength training
– Getting adequate, high-quality sleep
– Reducing stress
– Eating a nutritious, balanced diet
– Limiting alcohol intake
– Stopping smoking
– Taking steps to treat sleep apnea
– Managing chronic illnesses, like diabetes, heart disease, and HIV

While medications, supplements, and specialized diets are marketed to boost testosterone levels, there is little evidence that these products work effectively if testosterone is already in the normal range.


Some of the key takeaways about what causes low testosterone in men include:

– Many factors can affect testosterone levels, including aging, genetics, obesity, illness, injury, medications, and lifestyle habits.
– Primary hypogonadism results from testicular dysfunction, while secondary hypogonadism is caused by pituitary/hypothalamic disease.
– Obesity, metabolic syndrome, and diabetes strongly contribute to low testosterone.
– Symptoms of low testosterone include sexual dysfunction, loss of muscle mass, increased body fat, low energy, and mood issues.
– Diagnosis should involve both blood testing and evaluating for clinical symptoms.
– Treatment may consist of testosterone therapy, targeting underlying health conditions, medication changes, and lifestyle interventions.
– Some natural decline in testosterone occurs with aging, but healthy lifestyle choices can help slow this drop.

While testosterone levels naturally fall as men get older, maintaining a healthy lifestyle and managing chronic illnesses can go a long way towards preserving healthy testosterone levels and reducing bothersome symptoms of deficiency.