As an adult male with reduced bilateral testicular volume (~9 mL) but normal sperm concentration and normal serum testosterone, is this testicular atrophy?

Testicular Volume Assessment and Clinical Significance

Your testicular volume of 9 mL bilaterally is definitively below the 12 mL threshold that defines testicular atrophy, but your normal sperm count (56 million/mL) and testosterone (40 nmol/L) indicate that your testes are still functioning adequately despite their small size. 1

Understanding Your Measurements

Your bilateral testicular volume of 9 mL places you in a concerning category:

• Testicular volumes below 12 mL are definitively considered atrophic and warrant clinical investigation, particularly when associated with fertility concerns or risk factors like cryptorchidism. 1
• Despite this small size, your sperm concentration of 56 million/mL exceeds the WHO reference limit of 16 million/mL by more than threefold, confirming that spermatogenesis is currently preserved. 1, 2
• Your testosterone level of 40 nmol/L is in the high-normal to elevated range, making primary testicular failure unlikely at this time. 1

Why Small Testes Can Still Produce Normal Sperm

The apparent paradox of small testes with normal function occurs because:

• Testicular volume correlates most strongly with total sperm count and FSH levels, but individual variation exists—some men maintain adequate spermatogenesis despite reduced testicular size. 2
• Bilateral testicular volumes of 10–12 mL typically indicate oligospermia rather than azoospermia, with FSH levels above 7.6 IU/L suggesting impaired but not absent spermatogenesis. 3
• Your case demonstrates that testicular volume alone cannot definitively predict fertility status; semen analysis is essential to assess actual reproductive function. 1

Critical Next Steps

Hormonal Evaluation (Mandatory)

Obtain morning serum FSH, LH, and total testosterone on two separate occasions (08:00–10:00 h) to establish baseline values and distinguish primary testicular dysfunction from secondary causes. 1

• If FSH is elevated (>7.6 IU/L), this indicates reduced testicular reserve and impaired spermatogenic capacity, meaning you have less ability to compensate if additional stressors occur. 1
• Elevated LH with normal testosterone suggests the pituitary is compensating for some degree of testicular resistance. 1
• Measure SHBG and calculate free testosterone if total testosterone appears borderline, as high SHBG can reduce bioavailable testosterone. 1

Verify Testicular Volume Measurement

Request a repeat scrotal ultrasound with explicit attention to proper measurement technique using the Lambert formula (Length × Width × Height × 0.71), as the traditional ellipsoid formula (0.52 coefficient) systematically underestimates volume by 20–30%. 1

• Technical errors in caliper placement can lead to severely incorrect volume calculations, and if you have normal fertility with no history of cryptorchidism, the likelihood of true severe atrophy is lower. 1
• High-frequency probes (>10 MHz) should be used to maximize resolution and accurate measurement. 1

Screen for Underlying Causes

Obtain a detailed history focusing on:

• History of cryptorchidism (undescended testes), which is the single most important risk factor for testicular atrophy and substantially increases cancer risk. 1, 3
• Use of anabolic steroids, testosterone, opioids, or glucocorticoids, which can cause reversible testicular atrophy. 1
• Prior chemotherapy or pelvic/testicular radiation, which causes irreversible testicular damage. 1
• Systemic diseases including diabetes, chronic liver disease, chronic kidney disease, or HIV infection. 1

Physical Examination Priorities

Evaluate for palpable varicocele on standing examination, as correction of clinical varicoceles can improve both semen quality and fertility rates. 3

• Bilateral testicular hypotrophy in men with varicoceles predicts severe impairment of semen quality, with nearly nine times higher odds of total motile sperm count below 20 million compared to men without hypotrophy. 4

Cancer Risk Considerations

Men younger than 30–40 years with testicular volume <12 mL have a ≥34% risk of intratubular germ cell neoplasia (TIN) in the contralateral testis if testicular cancer develops. 1

• If untreated, invasive testicular tumor develops in 70% of TIN-positive testes within 7 years. 1
• History of cryptorchidism combined with volume <12 mL markedly increases malignancy risk and mandates intensified surveillance. 1
• Teach yourself testicular self-examination given the increased cancer risk associated with smaller testicular volumes. 1

Fertility Preservation Strategy

Immediate Actions

Bank sperm now—collect 2–3 separate ejaculates with 2–3 days abstinence between collections—to provide insurance against technical failures, poor post-thaw recovery, or need for multiple treatment attempts. 1, 3

• Once azoospermia develops, even microsurgical testicular sperm extraction (micro-TESE) only achieves 40–50% sperm retrieval rates, so preservation while parameters are normal is critical. 1

Protective Measures

Never use exogenous testosterone or anabolic steroids, as these completely suppress spermatogenesis through negative feedback on the hypothalamus and pituitary, causing azoospermia that can take months to years to recover. 1, 3

• Avoid gonadotoxic medications when possible to prevent further decline in testicular function. 1
• Optimize modifiable factors: smoking cessation, maintain healthy body weight (BMI <25), minimize heat exposure to the testes. 5

Monitoring Protocol

Repeat semen analysis every 6–12 months to detect early decline in sperm parameters, as single analyses can be misleading due to natural variability. 1, 3

• If sperm concentration drops below 20 million/mL or approaches 5 million/mL, urgently bank additional specimens and consider genetic testing (karyotype and Y-chromosome microdeletion analysis). 1, 3

Common Pitfalls to Avoid

• Do not assume normal sperm count means no concern—your reduced testicular reserve means you have less capacity to compensate for future insults (illness, medications, aging). 1
• Do not delay fertility preservation—testicular atrophy can progress, and waiting until parameters decline reduces your options. 1, 3
• Do not start testosterone replacement without clarifying fertility intentions first, as it will cause complete suppression of spermatogenesis. 1
• Do not ignore a size discrepancy >2 mL or 20% between testes, as this warrants ultrasound evaluation to exclude pathology. 1

When to Seek Urgent Urology Referral

Immediate referral is indicated if:

• Palpable testicular mass develops 1
• Rapid testicular atrophy occurs 1
• Severe oligospermia (<5 million/mL) develops 1
• Age <30 years with history of cryptorchidism, given the ≥34% TIN risk 1