Testicular atrophy is the shrinking of your testicles (“balls”). This is not the same thing as when your scrotum (“ball sack”) temporarily shrinks and shrivels up when exposed to cold. Rather, it is the actual reduction in the size of one or both of your testicles from what they normally are.
Testicular shrinkage commonly occurs with older age but can also be caused by medical conditions that affect the testicles (like varicoceles or testicular torsion) or medications that mimic the effects of testosterone (like anabolic steroids). Infections, alcohol overuse, and testicular cancer have also been implicated. In some cases, your fertility and ability to conceive may be affected.
A Note on Gender and Sex Terminology
Testicular atrophy affects people born with a penis who are typically assigned male at birth.
Verywell Health acknowledges that sex and gender are related concepts but are not the same. To accurately reflect our sources, this article uses terms like “male,” “man,” and “boy” as the sources use them.
What Is Testicular Atrophy?
Testicular atrophy is due to the loss of cells that line the network of tubes inside your testicles, called the seminiferous tubules. These include Sertoli cells and germ cells that produce sperm and Leydig cells that produce testosterone. This decreases the volume of the seminiferous tubules and, in turn, the size of your testicles.
Testicular atrophy can also affect the function of the testicles, leading to a decline in sperm count as well as a steep drop in testosterone levels (known as hypogonadism).
If testicular atrophy occurs before puberty, a person may also experience:
- Delayed sexual development
- A notable lack of facial, body, or pubic hair
- A disproportionately larger penis size compared to the testicles
After puberty, testicular atrophy may be accompanied by symptoms such as:
- Depression
- Enlarged breasts (gynecomastia)
- Erectile dysfunction
- Fatigue
- Infertility
- Low sex drive (libido)
- Loss of muscle mass
- Loss of armpit or pubic hair
Testicular Atrophy vs. Microorchism
While testicular atrophy is a decrease in testicle size, it is not the same thing as microorchidism, a condition in which you are born with abnormally small testicles.
Testicular atrophy is generally acquired with age or a medical condition. Microorchidism is most commonly the result of a congenital (present at birth) condition, such as Klinefelter’s syndrome or Prader-Willi syndrome.
Causes of Male Genital Atrophy
The causes of testicular atrophy vary depending on a person’s age. Based on the cause, the condition may be reversible or irreversible, and unilateral (one-sided) or bilateral (two-sided).
Children
Four conditions closely associated with testicular atrophy in children are:
- Cryptorochidism is an undescended testicle, a usually painless condition that affects 1% to 2% of baby boys. Testicular atrophy typically occurs when the testicle does not move into the correct position by age 2, by which time surgery is needed.
- Mumps orchitis is a complication of mumps (a viral disease preventable by vaccine) that results in acute inflammation of the testicles (orchitis). Around half of those affected will experience testicular shrinkage, while one in 10 will experience a drop in their sperm count.
- Varicocele is the abnormal swelling of the spermatic veins that carry blood from each testicle. Between 8% and 14% of boys ages 11 to 14 are affected. It is usually due to the failure of valves inside the veins. Shrinkage can occur if the blood flow is chronically impaired.
- Testicular torsion is a medical emergency in which a testicle is abnormally twisted, cutting off blood flow. It can occur at any age but is most commonly seen between ages 12 and 18. Delayed treatment can lead to testicular shrinkage and even possible loss of a testicle.
More often than not, conditions like these cause unilateral atrophy, although a significant number of cases involve both testicles. Bilateral testes atrophy may occur due to other causes (environmental or genetic).
Adults
Testicular atrophy in adults has several common and uncommon causes. Specialists known as urologists can often narrow the causes based on whether the condition is unilateral or bilateral, such as with:
- Aging: From age 40 onward, testosterone levels decline in men as Leydig cells are gradually lost with age. This, in turn, decreases the number of Sertoli and germ cells that rely on testosterone for growth. Testicular shrinkage commonly tracks alongside declines in testosterone.
- Bacterial orchitis: In adults, orchitis is often the result of a sexually transmitted infection (STI) like gonorrhea and chlamydia. Cases like this are most often seen between the ages of 19 and 35. Left untreated, this can lead to testicular shrinkage, more often unilaterally.
- Urinary tract infection (UTI): Another cause of bacterial orchitis is a severe UTI. In males, this is most often associated with the use of a Foley catheters, a tube inserted through the urethra that helps people with severe problems release urine.
- Alcohol use disorder: Drinking large amounts of alcohol damages Leydig cells, leading to areas of collapse within the seminiferous tubules. Over time, testicular shrinkage can occur, which is typically bilateral and irreversible even after the drinking has stopped.
- Anabolic steroids: These drugs, structurally related to testosterone, are often used illicitly for bodybuilding. With ongoing use, anabolic steroids “turn off” Leydig cells, causing bilateral atrophy. In most cases, shrinkage can be reversed once the drugs are stopped.
- Testosterone replacement therapy (TRT): TRT is commonly used to treat male hypogonadism. As with anabolic steroids, TRT can lead to bilateral shrinkage as the body needs to produce less testosterone on its own. Atrophy may or may not be reversed after treatment is stopped.
- Ischemic orchitis: This is a common complication of an inguinal (groin) hernia repair, accounting for 2% to 8% of cases. Localized scarring can reduce blood flow to the testicle, causing unilateral shrinkage within days of the surgery.
- Testicular cancer: In rare cases, cancer of a testicle can cause testicular shrinkage. On the flip side, certain causes of testicular atrophy, such as cryptorchidism, can increase the risk of cancer by as much as sixfold.
Risks and Long-Term Effects
One of the main concerns of testicular atrophy is its possible impact on fertility. The risk can vary by the underlying cause and whether the condition is unilateral or bilateral. The risk is most noticeable early in life.
Examples include:
- Cryptorchidism: Studies suggest that around 10% of infertile men have a history of an undescended testicle. Men with bilateral involvement are at a sixfold increased risk.
- Mumps orchitis: Up to 30% of men with a history of mumps orchitis will experience impaired fertility or infertility in later life. The risk is greater in those with bilateral orchitis.
- Varicocele: This is the most common identifiable cause of male infertility worldwide, seen in up to 35% of infertile men. Again, bilateral involvement increases the risk.
There is also an increased risk of sexual dysfunction, including erectile dysfunction (ED), among people who experience hypogonadism as a result of testicular atrophy. This is especially common with aging-related hypogonadism in which 52% of men ages 40 to 69 have some degree of ED.
Even beyond the risk of sexual dysfunction or the loss of fertility, testicular shrinkage can take an emotional toll. Some people express feeling self-conscious, believing that smaller testicles “make them less of a man.” This can lead to sexual dysfunction and signs of clinical depression.
Diagnosis
Testicular atrophy is often detected when a person suddenly notices that one or both of their testicles are smaller than they used to be. It may also be detected during a physical exam by a healthcare provider, who notices size does not match age.
Although testicle size can vary from person to person, testicles are generally 4 to 5 centimeters (cm) long, 3 cm high, and 2.5 cm wide in most mature adults.
By contrast, testicular atrophy is diagnosed from one of the following characteristics:
- A testicle is more than 50% smaller than the size expected for your age.
- A testicle has decreased in volume by more than 20% from a prior measurement.
To make the diagnosis, a specialist called a urologist will perform a scrotal ultrasound, which uses high-frequency sound waves to create detailed images of the testicle. Based on the length, width, and height of a testicle, the urologist can calculate its volume and compare it to either a previous scan or the median size of testicles of people your age.
The specialist will also order a serum testosterone test to measure the amount of testosterone in your blood. Values under less than 250 nanograms per deciliters (ng/dL) indicate hypogonadism and the possible need for testosterone replacement therapy.
Treatment and Reversibility
In most cases, the first-line approach to testicular atrophy is to treat the underlying cause. For bacterial infections like gonorrhea, chlamydia, or a severe UTI, this would involve the early use of antibiotics. For viral infections like mumps, the drug interferon may help reduce the risk of atrophy and future infertility.
Surgery may be needed to repair structural abnormalities like an undescended testicle, varicocele, and (most especially) testicular torsion. Early treatment almost invariably affords better outcomes.
For shrinkage caused by TRT and anabolic steroids, the discontinuation of the drug may reverse symptoms depending on how long you have taken them and at what dose. Even then, it can take up to a year or more for symptoms to fully reverse.
Not every case of testicular atrophy can be reversed. This is especially true when atrophy is related to aging or caused by chronic alcohol use. In such cases, the aim may be to prevent further shrinkage.
Drugs sometimes prescribed include:
- Human chorionic gonadotropin (HCG): This is a hormone similar in structure to luteinizing hormone (LH) that tells the body when to produce testosterone. By stimulating Leydig cells, HCG can help restore testicular function and help maintain its current size.
- Clomid (clomiphene): This is a fertility drug sometimes used to treat testicular atrophy. Rather than mimicking LH, it helps stimulate the production of LH, increasing both sperm production and testosterone levels.
Both of these drugs are commonly prescribed to people on TRT who experience testicular shrinkage. However, in both cases the use is off-label, meaning the drugs have not been specifically approved by the Food and Drug Administration (FDA) for this purpose.
Alternative treatments sometimes used for testicular atrophy are curcumin found in turmeric, traditional Chinese medicines like Wuzi Yanzong, goji berries, or ginseng, and probiotic supplements like Lactobacillus reuteri. With that said, there is little research to support their use and most of it is confined to animal studies.
How to Feel Comfortable With a Provider
Talking to a healthcare provider about your genitals can feel uncomfortable under the best of circumstances. Discussing the size of your testicles can compound these feelings given that it can open the door to questions about your sexual health and anabolic steroid use.
As awkward as this may seem, any change in the size of your testicles warrants investigation, especially if it occurs suddenly or with symptoms. Even if it appears to be related to aging, it is worth getting it checked out if you are feeling distressed, anxious, or depressed.
Urologists are specially trained in diseases and conditions affecting the male reproductive system. As such, they are used to speaking about issues related to the penis, testicles, scrotum, or prostate gland and can tell you if what you are experiencing is normal or in need of investigation.
To aid with the diagnosis (and make the conversation more stress-free), focus on the facts by simply explaining:
- When you first noticed a change in the size of your testicle
- If this is a recent or ongoing concern
- If you are experiencing other symptoms (like pain, a visible discharge, or a mass)
If you have been trying to conceive but have not been able to, add that to your list of concerns.
By providing the provider with a clear, concise snapshot of your concerns—and answering questions as honestly as you can—they can narrow the causes more quickly without any unnecessary fuss.
Summary
Testicular atrophy is the significant reduction of the size of your testicles. While this commonly occurs with older age, it may also be due to conditions like cryptorchidism, mumps orchitis, varicocele, and testicular torsion.
Testicular atrophy can also occur during adulthood due to sexually transmitted infections, excessive alcohol use, anabolic steroids, and testosterone replacement therapy (TRT). Some of these conditions are reversible with treatment, while others, like TRT, may require medications to prevent further testicular shrinkage.
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