I'm a male of reproductive age with a normal sperm count, but I've noticed my testicles have decreased in size over the past year, is testicular atrophy likely?

Testicular Atrophy Assessment in Men with Normal Sperm Count

Your testicles may have decreased in size, but a normal sperm count does not rule out testicular atrophy—you need objective measurement with an orchidometer or ultrasound to confirm whether size reduction has actually occurred. 1

Understanding the Relationship Between Testicular Size and Sperm Production

Testicular volume and sperm production are correlated but not perfectly linked. Mean testicular size strongly correlates with total sperm count and sperm concentration, but this relationship is not absolute 2. Men can have reduced testicular volume while maintaining adequate sperm production, particularly in early stages of testicular dysfunction 1.

Key Clinical Thresholds

• Testicular volumes less than 12 ml are definitively considered atrophic and warrant further investigation 2
• Normal adult testicular volume ranges from approximately 15-18 ml, corresponding to a testicular length of about 4 cm 2
• A size discrepancy between testes greater than 2 ml or 20% warrants ultrasound evaluation to exclude pathology 2

Why Normal Sperm Count Doesn't Exclude Atrophy

The critical insight is that testicular atrophy can be present even with preserved spermatogenesis, especially in early stages. 1 Several scenarios explain this apparent paradox:

• Focal preservation of spermatogenesis: Even atrophied testes may have scattered areas of functioning seminiferous tubules that maintain sperm output 1
• Compensatory mechanisms: Elevated FSH levels (>7.6 IU/L) indicate the pituitary is working harder to maintain sperm production despite testicular damage 1
• Progressive nature: Testicular atrophy often develops gradually, and sperm production may remain adequate initially before eventual decline 3

Essential Next Steps for Accurate Assessment

Objective Measurement is Mandatory

You cannot reliably assess testicular size change by subjective perception alone. Obtain objective measurement using:

• Prader orchidometer examination by a healthcare provider—this is a good surrogate for ultrasound volume and is cost-effective 2
• Scrotal ultrasound if physical examination is difficult or if orchidometer measurement suggests volumes <12 ml 1, 2
• Ultrasound should use high-frequency probes (>10 MHz) and calculate volume using the Lambert formula: Length × Width × Height × 0.71 1

Hormonal Evaluation

Measure serum FSH, LH, and testosterone to assess testicular function 1:

• FSH >7.6 IU/L with testicular atrophy strongly suggests spermatogenic failure, even if current sperm count appears normal 1
• Elevated FSH indicates reduced testicular reserve, meaning less capacity to compensate if additional stressors occur 1
• The combination of small testes and elevated FSH predicts future fertility decline 1

Repeat Semen Analysis

• Single semen analyses are insufficient due to natural variability (coefficient of variation 42-75%) 4
• Obtain at least 2-3 semen analyses separated by 2-3 months to establish whether parameters are stable or declining 1
• Assess combined parameters (concentration, motility, morphology, total count) rather than concentration alone 1

Common Causes of Testicular Atrophy to Investigate

Varicocele

• Varicoceles cause significant ipsilateral testicular atrophy and are the most common reversible cause of male factor infertility 5, 3
• Physical examination should assess for palpable varicocele on standing examination 1
• Varicocele-related atrophy can be progressive, and both testes may eventually be affected 3

Prior Trauma or Surgery

• Scrotal trauma causes testicular atrophy in approximately 50% of cases 6
• Inguinal hernioplasty can cause testicular atrophy due to thrombosis of spermatic cord veins from surgical dissection 7

Medications and Exposures

• Chronic opioids, corticosteroids, or anabolic steroids suppress the hypothalamic-pituitary-gonadal axis, leading to testicular atrophy 1
• Exogenous testosterone completely suppresses spermatogenesis and causes testicular atrophy 1
• Exposure to toxins (lead, cadmium) or occupational exposures may contribute 8

Systemic Diseases

• HIV/AIDS, diabetes, prior chemotherapy, or testicular radiation can cause progressive testicular damage 1
• Thyroid dysfunction disrupts the hypothalamic-pituitary-gonadal axis 1

Critical Monitoring and Fertility Preservation

Cancer Risk Considerations

Atrophic testes (<12 ml) are a risk factor for testicular cancer and require monitoring 1:

• Men with testicular atrophy should perform regular testicular self-examination 1
• History of cryptorchidism substantially increases cancer risk and mandates closer surveillance 1
• In men under 30-40 years with volume <12 ml, there is a >34% risk of intratubular germ cell neoplasia if testicular cancer develops 1

Fertility Preservation Strategy

If testicular atrophy is confirmed, strongly consider sperm cryopreservation 1:

• Men with reduced testicular reserve are at risk for progressive spermatogenic failure 1
• Once azoospermia develops, even microsurgical testicular sperm extraction (micro-TESE) only achieves 40-50% sperm retrieval rates 1
• Bank at least 2-3 ejaculates to provide backup samples and maximize future fertility options 1

Common Pitfalls to Avoid

• Do not rely on subjective perception—within-subject variation in testicular size perception is unreliable; always obtain objective measurement 4
• Do not assume normal sperm count means normal testicular size—these parameters are correlated but not perfectly linked 1, 5
• Do not delay evaluation if atrophy is confirmed—progressive testicular atrophy can lead to irreversible fertility loss 3
• Never start testosterone therapy if future fertility is desired—it will cause azoospermia that can take months to years to recover 1