Testicular atrophy refers to the shrinking of your testicles, which are the two male reproductive glands located in the scrotum. The scrotum’s main function is to regulate the temperature around the testicles, which it does by shrinking in response to cold temperatures and relaxing in response to warmer temperatures. This can make it feel like your testicles are larger or smaller than usual sometimes.

However, testicular atrophy refers to shrinkage in your actual testicles, not your scrotum. This can be due to several things, including an injury, an underlying condition, or exposure to certain chemicals.

Keep reading to learn more about the possible causes and whether testicular atrophy is reversible.

While the main symptom of testicular atrophy is shrinkage of one or both testicles, several other symptoms can accompany it, depending on your age.

Symptoms before puberty

For people who haven’t gone through puberty, additional symptoms of testicular atrophy include not developing secondary sexual characteristics, such as:

  • facial hair
  • pubic hair
  • larger penis size

Symptoms after puberty

If you’ve gone through puberty, additional symptoms of testicular atrophy can include:

  • decreased sex drive
  • infertility
  • reduced muscle mass
  • absent or reduced facial hair growth
  • absent or reduced pubic hair growth
  • softer testicles

Orchitis

Orchitis refers to inflammation of the testicles. Its main symptoms are pain and swelling in the testicles, but it can also cause nausea and fever. While the swelling can initially make your testicles look larger, orchitis can eventually lead to testicular atrophy.

There are two main types of orchitis:

  • Viral orchitis. This is usually caused by the mumps virus. Up to one-third of men who have the mumps after puberty develop orchitis. This often happens within four to seven days of getting the mumps.
  • Bacterial orchitis. This type of orchitis is often due to a sexually transmitted infection (STI), such as gonorrhea or chlamydia. In some cases, it’s caused by an infection in your urinary tract or from having a catheter or other medical instrument inserted into your penis.

Other causes

In addition to orchitis, several other things can cause testicular atrophy, including:

  • Age. While women go through menopause, some men go through a similar process known as andropause. This causes low testosterone levels, which can lead to testicular atrophy.
  • Varicoceles. A varicocele is like a varicose vein, but located near the testicles instead of the legs. Varicoceles typically affect the left testicle and can damage the sperm-producing tubes within the testicles. This can make the affected testicle smaller.
  • Testicular torsion. This happens when a testicle rotates and twists the spermatic cord, which carries blood to the scrotum. Reduced blood flow can cause pain and swelling in your testicles. If it’s not treated within a few hours, it can cause permanent testicular atrophy.
  • Testosterone replacement therapy (TRT). Some men undergoing TRT experience testicular atrophy. This is because TRT can stop the production of gonadotropin-releasing hormone (GnRH). Without GnRH, the pituitary gland stops making luteinizing hormone (LH). Without LH, the testicles stop secreting testosterone, leading to smaller testicles.
  • Anabolic steroid or estrogen use. Taking anabolic steroids or estrogen supplements can cause the same effect on hormones as TRT.
  • Alcohol use disorder. Alcohol can cause both low testosterone and testicular tissue damage, both of which can lead to testicular atrophy.

To figure out what’s causing your testicular atrophy, your doctor may ask you some questions about your lifestyle and sexual history. This will help them determine whether alcohol or an STI could be the cause.

Next, they’ll likely examine your testicles, checking their size, texture, and firmness. Depending on what they find, they may order some tests, including:

Treating testicular atrophy depends on its cause. If it’s due to an STI or other infection, you’ll likely need a round of antibiotics. In other cases, you’ll need to make some lifestyle changes. In rare cases, you may need surgery to treat cases of testicular torsion.

While the conditions that can cause testicular atrophy are usually easy to treat, testicular atrophy itself isn’t always reversible. In many cases, early treatment increases the likelihood of testicular atrophy being reversible. This is especially important if your testicular atrophy is due to testicular torsion. Waiting more than even a few hours to seek treatment can lead to permanent damage.

There’s no proven way to naturally reverse testicular atrophy.

Many things can cause your testicles to shrink, from steroid use to STIs. Regardless of the cause, it’s important to talk to your doctor as soon as you start noticing any shrinkage. Early treatment is key for successfully reversing testicular atrophy.