Testosterone and Testicular Atrophy

Testosterone and Testicular Atrophy

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.


Testicles (also referred to as gonads) are oval-shaped male sex glands which produce testosterone and sperm, with individual organ sizes depending on each person.

Smaller testicles could indicate low production of male sex hormone, known as hypogonadism

The Function of the Testicles

Testicles (or male gonads) serve several functions. Their primary task is producing and secreting testosterone, a male sexual hormone.

Furthermore, testes also play a vital role in regulating sexual functions and the hypothalamus-pituitary system which controls reproduction.

Their seminiferous tubules contain undeveloped sperm-producing cells called Sertoli cells which undergo spermatogenesis, then connect via ducts to wider conduits on each testicle called the Rete testis which transports its cargo onto tightly wound tubes called Epididymis for storage while it finishes maturation.

The testicles are oval-shaped organs located behind the penis and right in front of the anus on a person's body, weighing 0.35 to 0.5 ounces (10-15 grams) per testicle according to Virtual Medical Centre (VMC).

They've been described as olives or small eggs in size and protected from physical trauma by being housed within an organ known as the scrotum that provides insulation against heat loss - keeping both organs cooler than most parts of their environment.

The testicles are connected to each other and the body via a cord called the spermatic cord, which contains nerves and blood vessels.

Each testis also has a vas deferens, a tube which transports sperm from its testis to the penis where it travels out of its own testis through a process known as ejaculation or penetration before exiting via the urethra in its natural course.

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Testosterone Explained

Testosterone is the main male sexual hormone, yet also present in females at lower concentrations.

It's produced in both the testicles (Leydig cells for men) and ovaries (in women). Testosterone plays a vital role in male development and function.

It promotes genital growth, facial hair growth and voice deepening during puberty, controls sexual drive, helps make sperm, promotes muscle growth and organ health, among other responsibilities.

Testosterone is an androgen hormone, meaning that it interacts with various glands to control their activity and maintain balance.

LHRH interacts with other androgens to decrease hypothalamus release of gonadotropin-releasing hormone; activates pituitary gland production of luteinizing hormone; and directs testes development during spermatogenesis.

Too little naturally-occurring testosterone can result in symptoms for men, including muscle loss, loss of facial and body hair and wrinkled, papery skin - sometimes known as male menopause (andropause). Testosterone levels naturally decline with age.

Testicular Atrophy Explained

If your scrotum has shrunk significantly over time, this could be testicular atrophy - an age-related health condition which must be diagnosed and treated promptly to prevent further damage to its structure. Here is what you should know about testicular atrophy diagnosis and treatment.

Testicles are two male reproductive glands located within the scrotum that produce sperm and testosterone for male reproduction.

Testicular atrophy leads to a decrease in sperm count and low levels of testosterone production, manifesting itself through pain or swelling in either testicle.

Symptoms include pain or swelling that is irreversible but can be alleviated through certain steps, including cutting back on alcohol consumption, drugs or smoking as well as practicing sexual abstinence for some time.

Short-term testicular shrinkage due to cold temperatures is normal; however, any testicle which continues to get smaller should be checked by a physician as ongoing atrophy may indicate an underlying issue that affects fertility.

Some of the primary causes of testicular atrophy include orchitis, varicocele and reduced testosterone due to age.

Orchitis is an infection of the testicles which leads to fullness and swelling for several days followed by drastic size decrease.

Varicocele, similar to varicose veins but located closer to testicles instead of legs, often occurs on one testicle on its left side and damages its sperm-producing tubes within it, making the testicle appear smaller than usual.

Testosterone Replacement Therapy and Testicular Atrophy

Hypogonadism, in which the body fails to produce sufficient levels of testosterone, is another condition which can cause testicles to shrink.

It may be genetic (inherited from birth), or result from other medical issues like damage or trauma to testicles, varicocele, and vascular problems; and can even occur following withdrawal from anabolic androgenic steroids.

Testosterone replacement therapy is an effective solution for men suffering from low testosterone levels, commonly referred to as Low-T.

Low-T may occur as a result of age, opioid medications and certain anabolic steroids prescribed, injury to or surgery on testicles and other causes.

Testosterone replacement therapy (TRT) has proven to alleviate its symptoms - loss of libido and fatigue for starters - while simultaneously improving muscle mass density, bone density and energy levels. It is only available by prescription and is a controlled substance in many regions around the world.

However, it's important to keep in mind that administered testosterone may cause your testicles to decrease in size - a condition known as atrophy - due to reduced production of sperm and other hormones like LH.

A study published in 2022 noticed that testicular atrophy was significant after 6 months of prescribed TRT use. It was also noted that injectable forms of TRT appeared to have more of a damaging effect than oil based products.

Although atrophy can be temporary side effects of TRT medication use, once discontinued it can often reverse itself and return back to its former size. 

Anabolic Steroids and Testicular Atrophy

Your hypothalamus and pituitary gland are responsible for controlling how much testosterone your testicles produce, with gonadotropin-releasing hormone (GnRH) from your brain being sent directly to the pituitary gland to secrete luteinizing hormone (LH).

This travels directly to your gonads and triggers them to make both testosterone and sperm.

Any issues in either of these regions that lead to decreased LH production is known as male hypogonadism.

Some conditions and medications can cause your testicles to either expand or shrink, with steroids often being the primary factor.

Steroids mimic natural sex hormones rendering Leydig cells that produce testosterone production obsolete. This causes your testicles to atrophy rapidly if taken too frequently, which is why it's imperative that any use is stopped immediately once symptoms of atrophy arise.

A 2017 study recommends stopping the use of steroids to reverse the condition of testicualar atrophy.


Testosterone is a male hormone produced by the testicles that gradually increases with age, helping many men feel younger and more energetic.

Some men taking testosterone may experience issues including gynecomastia (male breast tissue), worsening sleep apnea, acne breakouts and hair thinning on their chest area. There's also an increase risk for prostate cancer as well as decreased sperm production or shrinkage of testicles are repercussions from taking testosterone therapy.

Testicular atrophy is one of the primary side effects of testosterone replacement therapy, in which testicles lose their ability to produce LH and FSH required for sperm production.

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