You Do Not Have Testicular Atrophy
Based on your ultrasound measurements (3.1–4.0 cm length), normal FSH (9.5 IU/L) and LH (7.2 IU/L) levels, and confirmation by a urologist that your testes are normal size, you do not have testicular atrophy. Your testicular volumes fall within or very close to the normal range, and your hormone levels indicate preserved testicular function.
Understanding Your Testicular Measurements
Volume Calculation from Length Measurements
A testicular length of 4.0 cm corresponds to a volume of approximately 15–18 mL, which is well above the 12 mL threshold that defines atrophy. 1
Even your smaller measurements of 3.1 cm and 3.5 cm correspond to volumes of approximately 10–13 mL, which places you at or just below the lower limit of normal but does not constitute definitive atrophy in the context of normal hormones and clinical assessment. 1
The 12 mL threshold is the critical cut-off: volumes below this are associated with impaired spermatogenesis and increased risk of intratubular germ cell neoplasia, but your measurements suggest you are at or above this threshold. 1
Why Measurement Variability Occurs
Technical error in ultrasound caliper placement is extremely common and can lead to volume discrepancies of 20–30%, especially when measuring testicular width, which is the most error-prone dimension. 1
The Lambert formula (Length × Width × Height × 0.71) should be used for accurate volume calculation, not the traditional ellipsoid formula (0.52 coefficient), which systematically underestimates volume. 1
Inter-scan variability is expected when different sonographers perform measurements or when technique is not standardized—true biological change in testicular size over 4 weeks in adults is extremely unlikely unless acute pathology is present. 1
Your Hormone Levels Confirm Normal Testicular Function
FSH and LH Interpretation
Your FSH of 9.5 IU/L is within the normal range (1–12.4 IU/L) and does not indicate primary testicular failure. 1
FSH >7.6 IU/L is associated with some degree of testicular dysfunction in research studies, but your level of 9.5 IU/L is only mildly elevated and does not preclude normal sperm production—many men with FSH in this range have normal fertility. 1, 2
Your LH of 7.2 IU/L is also within normal range (1–8.4 IU/L), indicating that your pituitary is not compensating for significant testicular failure. 1
The combination of borderline-normal FSH with normal LH suggests you have adequate testicular reserve, not primary testicular atrophy. 1
What These Hormone Levels Mean
Elevated FSH (>12–15 IU/L) with testicular atrophy would indicate primary testicular failure, but your FSH is well below this threshold. 1, 2
Men with true testicular atrophy (<12 mL volume) typically have FSH >12–15 IU/L and often show progressive elevation over time. 1, 2
Your hormone pattern is consistent with normal or borderline-reduced testicular reserve, not atrophy. 1
Clinical Confirmation by Your Urologist
Your urologist's assessment that your testes are "normal size" on physical examination is the most important clinical finding. 1
Physical examination by an experienced urologist using a Prader orchidometer is a validated method for testicular volume assessment and correlates well with ultrasound measurements. 1
The fact that your urologist found your testes to be normal size overrides minor measurement discrepancies on ultrasound, which are often due to technical factors. 1
What You Should Do Next
No Immediate Action Required
You do not need further imaging or repeat ultrasound unless new symptoms develop (testicular pain, rapid size change, palpable mass). 1
You do not need testicular biopsy given your normal hormone levels, normal clinical examination, and absence of high-risk features (age <30 with history of cryptorchidism or testicular cancer). 1
Optional: Fertility Assessment (If Relevant)
If you have fertility concerns or are planning to conceive, consider obtaining a semen analysis to directly assess sperm production, as testicular volume and FSH levels alone cannot definitively predict fertility. 1, 3
Semen analysis is the gold standard for evaluating male fertility and should include sperm concentration, motility, and morphology. 1, 3
If semen analysis shows sperm concentration >16 million/mL, your fertility is normal regardless of minor variations in testicular size. 1, 2
Monitoring Recommendations
Repeat hormone testing (FSH, LH, testosterone) in 6–12 months only if you develop symptoms of hypogonadism (low libido, erectile dysfunction, fatigue) or if fertility concerns arise. 1
Teach yourself testicular self-examination to monitor for any new masses or rapid size changes, though your cancer risk is not elevated given your normal testicular size and absence of cryptorchidism history. 1
Common Pitfalls to Avoid
Do Not Misinterpret Measurement Variability as Atrophy
A 0.9 cm difference between measurements (4.0 cm vs. 3.1 cm) is most likely due to technical error in caliper placement, not true testicular shrinkage. 1
Request that the same sonographer perform serial measurements using standardized technique if future ultrasounds are needed. 1
Do Not Start Testosterone Therapy
- Never start exogenous testosterone if you have any current or future fertility intentions, as it will completely suppress FSH and LH through negative feedback, causing azoospermia that can take months to years to recover. 1, 2
Recognize That "Borderline" Does Not Mean "Abnormal"
Your testicular volumes of 10–18 mL place you in the borderline-normal to normal range, not the atrophic range. 1
**Testicular volumes <12 mL are definitively considered atrophic** only when associated with elevated FSH (>12–15 IU/L), impaired semen parameters, or clinical symptoms—none of which you have. 1
When to Seek Further Evaluation
Red-Flag Symptoms Requiring Urgent Urology Referral
Palpable testicular mass or new hard nodule on self-examination. 1
Rapid testicular atrophy (noticeable shrinkage over weeks to months). 1
Severe oligospermia (<5 million/mL) on semen analysis, which would warrant genetic testing (karyotype and Y-chromosome microdeletion analysis). 1, 2
Non-Urgent Indications for Follow-Up
Infertility after 12 months of unprotected intercourse, which would prompt complete fertility workup including semen analysis and hormonal evaluation. 1, 3
Symptoms of hypogonadism (low libido, erectile dysfunction, fatigue, loss of muscle mass), which would warrant repeat testosterone measurement. 1