Testicular atrophy is a decrease in the size of one or both testicles. While testicle size varies naturally, a noticeable reduction often indicates a medical issue. This condition is distinct from the temporary shrinking of the scrotum in response to cold temperatures.
Defining Testicular Atrophy
Testicular atrophy is characterized by the shrinking of one or both testicles, often leading to reduced function. This reduction indicates a loss of functional tissue, such as germ cells that produce sperm and Leydig cells that produce testosterone. Size is typically assessed through physical examination, palpation, or an orchidometer. An orchidometer is a series of ellipsoid beads used to estimate testicular size, with volumes typically ranging from 1 to 25 milliliters (mL). Normal adult testicle size generally ranges from 3 to 5 centimeters in length and 2 to 4 centimeters in width, with a volume between 12.5 and 25 mL.
Hormonal and Lifestyle Influences
Hormonal imbalances and certain lifestyle choices can contribute to testicular atrophy. The use of exogenous hormones, such as anabolic steroids or testosterone replacement therapy (TRT), can suppress the body’s natural hormone production. When external testosterone is introduced, the brain signals the testicles to decrease their own production, leading to shrinkage. This occurs because the hypothalamus reduces the secretion of gonadotropin-releasing hormone (GnRH), which in turn suppresses the production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by the pituitary gland. LH and FSH are necessary for maintaining testicular size and function.
Low endogenous testosterone, a condition known as hypogonadism, can also result in testicular atrophy. This occurs due to insufficient testosterone production. The Leydig cells, located in the testicles, are responsible for creating testosterone, and damage to these cells can hinder production.
Lifestyle factors like chronic heavy alcohol consumption can also affect testicular health. Alcohol can directly damage Leydig cells and interfere with hormones signaling testosterone production. Heavy drinking can lead to reduced testosterone levels, in part by boosting an enzyme that converts testosterone into estrogen. Smoking can also negatively affect testicular function, impacting Leydig and Sertoli cells involved in testosterone production and sperm maturation.
Medical Conditions and Specific Causes
Beyond hormonal and lifestyle factors, various medical conditions and specific incidents can lead to testicular atrophy. A varicocele, which involves enlarged veins in the scrotum, can impair blood flow and temperature regulation around the testicles. This altered environment can negatively affect testicular function and size, as the increased temperature can damage the seminiferous tubules that constitute a large portion of testicular volume.
Infections also pose a risk to testicular tissue. Mumps orchitis, an inflammation of the testicle caused by the mumps virus, can damage testicular tissue and lead to atrophy, particularly if it occurs after puberty. Epididymitis, an inflammation of the epididymis often caused by bacterial infections, can similarly harm testicular tissue, resulting in shrinkage.
Direct trauma or injury to the testicles can also cause atrophy. Severe injuries can lead to damage, such as ruptures or contusions, affecting blood supply and tissue integrity. Testicular torsion, where the spermatic cord twists, cuts off blood supply to the testicle, and if untreated for several hours, can cause permanent damage and atrophy.
Cryptorchidism, a condition where one or both testicles fail to descend into the scrotum during development, can also lead to atrophy if left uncorrected. Certain medical treatments, such as chemotherapy and radiation therapy, can also induce testicular atrophy. These treatments, used for cancer, can damage germ cells and Leydig cells within the testicles, impairing their function and leading to a reduction in size.
When to Consult a Doctor
Seeking professional medical advice is important if you notice any changes in testicle size. Early diagnosis of testicular atrophy can help identify the underlying cause and determine appropriate management strategies.
Accompanying symptoms that warrant concern include pain or discomfort in the testicles, swelling, or changes in libido. Other signs such as erectile dysfunction, changes in facial or pubic hair growth, reduced muscle mass, or fertility concerns like difficulty conceiving also indicate a need for medical evaluation.
A doctor’s evaluation may involve a physical examination of the testicles, which can include palpation and measurement using an orchidometer. Blood tests to assess hormone levels, particularly testosterone, LH, and FSH, are often conducted to identify hormonal imbalances. Imaging techniques like ultrasound may also be used to visualize the testicles and surrounding structures, helping to determine the cause and extent of the atrophy.