Testosterone plays an important role in men’s lives. Medical research data shows that testosterone levels start declining naturally after the age of thirty. Besides the natural declinations, there can be multiple reasons why testosterone levels decline in men.
Common causes of low testosterone in men include injuries to testicles or hypothalmus, depression, and less or no physical activities. However, the good news is that there are proven medical treatments, like testosterone replacement therapy, that can help treat low testosterone.
In this blog, we will talk about what testosterone are, causes of low testosterone in men, and how to treat them medically.
Table of Contents
What is testosterone, and how is it produced?
Testosterone is a hormone, and it is mainly a male sex hormone. It is important for male growth and development, but women also have small amounts of it.
How is testosterone produced?
In men, testosterone is made mostly in the testes (balls). A small amount comes from the adrenal glands (small glands above the kidneys).
In women, the ovaries and adrenal glands make small amounts.
The brain controls testosterone production. The hypothalamus and pituitary gland send signals to the testes or ovaries to make it.
10 Causes of Low Testosterone in Men
We will divide this section into two parts to understand the causes of low testosterone in a better way. We divide the causes into Primary causes of low testosterone in men (problems in the testes) and Secondary causes of low testosterone in men (problems in the brain or other systems.
Causes of Low Testosterone Chart/Table
| Primary Causes of Low T | Secondary Causes of Low T |
| Klinefelter syndrome | Pituitary gland disorders |
| Testicular injury or infection | Hypothalamus disorders |
| Undescended testicles | Obesity |
| Cancer treatments | Chronic diseases |
| Aging | Medications and Steroids |
Primary Causes (Testes Not Working Properly)
1. Klinefelter syndrome
One of the main causes of low testosterone in men is Klinefelter syndrome. Klinefelter syndrome is a genetic disorder where a male is born with an extra X chromosome (XXY instead of XY). This affects testicle development and lowers testosterone production
How does it cause low testosterone?
- The testes are smaller and don’t make enough testosterone.
- The body may produce more estrogen (female hormone), leading to less muscle, more fat, and sometimes breast growth (gynecomastia).
- Many men with Klinefelter syndrome have infertility due to low sperm count.
2. Testicular Injury
The second cause of low testosterone is testicular injury or infection. The testicles (testes) are responsible for producing testosterone, and damage to them can disrupt hormone production.
Common Injuries and Infections That Lower Testosterone
- Physical trauma
- Orchitis
- Testicular torsion
How Does It Cause Low Testosterone?
1. Damages Leydig cells
These cells inside the testes make testosterone. Injury or infection destroys them, reducing hormone production.
2. Disrupts blood flow
Trauma or torsion can starve the testicles of oxygen, killing testosterone-producing tissue.
3. Triggers inflammation
Infections (like mumps orchitis) cause swelling, leading to long-term damage if untreated.
3. Undescended testicles
The third primary cause of low testosterone is undescended testicles (also called cryptorchidism). This condition occurs when one or both testicles fail to move down into the scrotum before birth.
How Does It Cause Low Testosterone?
1. Higher Temperature Damage
Testicles need to be in the scrotum to stay cooler than body temperature. If they remain inside the abdomen or groin, the heat damages sperm and testosterone-producing cells.
2. Underdeveloped Testicles
Without proper positioning, the testicles may not grow normally, leading to reduced Leydig cell function (cells that make testosterone).
4. Long-Term Hormone Problems
Even with corrective surgery, some men still have lower testosterone levels if the condition wasn’t treated early.
4. Cancer Treatments (Chemotherapy and Radiation)
The fourth primary cause of low testosterone is cancer treatments, including chemotherapy and radiation therapy. These treatments can damage the testicles and disrupt hormone production.
How Do Cancer Treatments Lower Testosterone?
1. Chemotherapy
Toxic drugs kill fast-growing cells, including Leydig cells (which produce testosterone).
It can cause temporary or permanent testicular damage, depending on the drug type and dosage.
2. Radiation Therapy
Direct radiation to the pelvis or lower abdomen destroys testosterone-producing cells.
Even scattered radiation (e.g., for leukemia) can affect hormone levels.
3. Surgery (Orchiectomy)
Removal of one or both testicles (for testicular/prostate cancer) directly eliminates testosterone production.
5. Aging (Late-Onset Hypogonadism)
The fifth primary cause of low testosterone is natural aging. After age 30, testosterone levels drop by about 1% per year. By age 70, many men have significantly lower levels.
Why Does Aging Lower Testosterone?
1. Testes Slow Down
Leydig cells (testosterone producers) become less efficient.
2. Pituitary Gland weakness
Releases less LH (the hormone that tells testes to make testosterone).
3. Increased SHBG
A protein that binds testosterone, leaving less free testosterone available.
4. Fat Gain and Muscle Loss
More body fat converts testosterone into estrogen, worsening the decline.
Read about: Symptoms of Low Testosterone in Men
Secondary Causes of Low Testosterone in Men
1. Pituitary Gland Disorders
The first secondary cause of low testosterone is pituitary gland disorders. Since the pituitary gland controls testosterone production, any damage or disease affecting it can disrupt hormone levels.
How Does It Cause Low Testosterone?
1. Disrupted LH and FSH Signals
The pituitary releases luteinizing hormone (LH), which tells the testes to make testosterone. If LH is low, testosterone drops.
2. Tumors (Prolactinoma)
A non-cancerous pituitary tumor can produce too much prolactin, which blocks testosterone production.
3. Trauma or Surgery
Head injuries, radiation, or pituitary surgery can damage hormone-producing cells.
4. Genetic Disorders
Conditions like Kallmann syndrome affect the pituitary’s ability to stimulate the testes.
2. Hypothalamus disorders
The second secondary cause of low testosterone is hypothalamus disorders. The hypothalamus is a small but crucial part of the brain that controls hormone production. When it malfunctions, testosterone levels drop.
How does it Cause Low Testosterone?
1. Disrupted GnRH Production
The hypothalamus makes gonadotropin-releasing hormone (GnRH), which signals the pituitary to release LH/FSH (hormones that tell the testes to produce testosterone). If GnRH is low, this entire chain breaks down.
2. Physical Damage
Brain tumors, head injuries, or infections (e.g., meningitis) can harm the hypothalamus.
3. Genetic Conditions
Kallmann syndrome (a disorder affecting smell and GnRH production) prevents normal puberty and testosterone development
4. Obesity
The third secondary cause of low testosterone is obesity. Excess body fat, especially around the belly, directly interferes with testosterone production through multiple mechanisms.
How Obesity Causes Low Testosterone
Increased Estrogen Conversion Fat cells contain aromatase, an enzyme that converts testosterone into estrogen, creating hormonal imbalance.
1. Chronic Inflammation
Obesity triggers inflammatory cytokines that suppress the hypothalamus-pituitary-testes axis, reducing LH/FSH signals.
2. Insulin Resistance
High insulin levels (common in obesity) lower sex hormone-binding globulin (SHBG), reducing active testosterone.
3. Leptin Resistance
Excess leptin (a fat hormone) disrupts GnRH production in the hypothalamus.
4. Chronic Diseases
The fourth secondary cause of low testosterone is chronic diseases. Certain long-term health conditions disrupt the body’s hormone balance and directly impair testosterone production.
How Chronic Diseases Cause Low Testosterone.
1. Type 2 Diabetes
- Insulin resistance damages testicular Leydig cells
- High blood sugar leads to vascular damage, reducing testicular blood flow
- Up to 50% of diabetic men have clinically low testosterone
2. Liver Disease
- Cirrhosis increases estrogen levels (due to impaired hormone breakdown)
- Reduces production of SHBG (sex hormone-binding globulin)
3. Kidney Disease
- Uremic toxins suppress hypothalamic GnRH production
- Dialysis and chronic inflammation further worsen hormone imbalance
4. HIV/AIDS
- Viral infection directly damages endocrine organs
- Chronic immune activation increases cortisol, which suppresses testosterone.
5. Medications and Steroids
The fifth secondary cause of low testosterone is medications and steroids. Many commonly prescribed drugs and performance-enhancing substances interfere with the body’s natural hormone production.
How Medications and Steroids Cause Low Testosterone.
1. Opioids (Painkillers)
- Directly suppress GnRH production in the hypothalamus
- Can reduce testosterone by 50% within weeks of regular use
- Includes oxycodone, hydrocodone, morphine, and methadone
2. Anabolic Steroids (Misuse)
- Shut down natural testosterone production completely
- Testes atrophy from disuse due to negative feedback
- Recovery may take 6-24 months after stopping
3. Glucocorticoids (Steroids)
- Prednisone and cortisone suppress pituitary LH secretion
- Chronic use leads to adrenal suppression
Treatment For Low Testosterone in Men
Low testosterone can be treated in several ways, depending on the cause. The most common treatment is testosterone replacement therapy (TRT), which boosts levels using gels, injections, or pellets. TRT improves energy, mood, muscle strength, and sex drive, but it may cause side effects like acne.
If you are living in Cape Town and suffering from low T levels, Prime Health Centre offers testosterone replacement therapy for men.
Conclusion
Low testosterone can affect energy, mood, and muscle strength. It can happen due to aging, medical conditions, or lifestyle factors. Primary causes affect the testes, while secondary causes come from the brain or metabolism.
Treatment options like testosterone replacement therapy (TRT) can help. Simple changes in diet and exercise may also improve levels. If you have symptoms, talk to a doctor. Proper care can restore balance and improve your health.
Note: The information shared above is just for research purposes. Don’t make any decision solely based on the above content. Always take an expert medical doctor’s advice.
