Would testicular atrophy affect a patient's sperm count?

Testicular Atrophy and Sperm Count: Direct Clinical Correlation

Yes, testicular atrophy will typically show in a patient's sperm count, though the relationship is not absolute and depends on whether the atrophy is unilateral or bilateral. 1

Understanding the Volume-Sperm Production Relationship

Testicular volume strongly correlates with total sperm count and sperm concentration. 1 The mechanism is straightforward: smaller testes contain fewer seminiferous tubules and reduced spermatogenic tissue, directly impairing sperm production. 2

Critical Volume Thresholds

• Testicular volumes less than 12 ml are definitively considered atrophic and associated with impaired spermatogenesis. 1
• Mean testicular size strongly correlates with both total sperm count and sperm concentration in a dose-dependent manner. 1
• In a study of 1,029 infertile men, sperm count and motility decreased progressively with declining testicular volume, with the lowest counts found in bilateral testicular atrophy. 2

Unilateral vs. Bilateral Atrophy: A Critical Distinction

The impact on sperm count depends heavily on whether one or both testes are affected:

Bilateral Atrophy

• Men with bilateral testicular hypotrophy are nearly 9 times more likely to have severely impaired sperm counts (total motile count <20 million) compared to men without atrophy. 3
• Bilateral atrophy consistently predicts for oligospermia or azoospermia. 1, 2

Unilateral Atrophy

• Unilateral hypotrophy alone does NOT reliably predict severely low sperm counts. 3
• However, men with ipsilateral testicular hypotrophy associated with varicoceles still show significantly reduced total motile sperm counts (80 million vs. 126 million in those without hypotrophy). 4
• The contralateral normal testis can often compensate sufficiently to maintain adequate sperm production. 3

Timing Considerations: The Spermatogenic Lag

A critical pitfall: current sperm counts reflect testicular function from 2-3 months ago, not current function. 5

• The complete cycle of sperm production takes approximately 64-74 days from initial spermatogonial division to mature spermatozoa in the ejaculate. 5
• If testicular atrophy is recent, the sperm count may still appear normal initially because those sperm were produced before the atrophy occurred. 5
• Repeat semen analysis should be performed at least 2-3 months after suspected testicular injury or shrinkage to accurately assess the impact. 5

Hormonal Markers Detect Dysfunction Earlier

FSH levels can indicate testicular dysfunction much earlier than semen analysis changes appear. 5

• Elevated FSH (>7.6 IU/L) suggests impaired spermatogenesis and correlates with testicular atrophy. 6
• FSH levels are negatively correlated with the number of spermatogonia—higher FSH indicates decreased sperm production. 6
• Hormonal evaluation should be performed immediately when testicular shrinkage is detected, as these markers reflect current testicular function. 5

Important Clinical Caveats

Severe Atrophy Doesn't Mean Zero Sperm

• Even with severe testicular atrophy (volume ≤2 ml), microsurgical testicular sperm extraction (micro-TESE) successfully retrieves sperm in 55% of cases. 7
• Testicular volume does not affect sperm retrieval rates for micro-TESE—men with volumes ≤2 ml had identical retrieval rates (55%) as those with larger testes. 7
• This occurs because focal areas of spermatogenesis can persist even in severely atrophic testes. 1

Age and Etiology Matter

• In men with severe atrophy (≤2 ml) and Klinefelter syndrome, those younger than 30 years had an 81.8% sperm retrieval rate versus only 33% in older men without Klinefelter syndrome. 7
• Younger age was the only preoperative factor associated with successful sperm retrieval in men with small testes. 7

Practical Clinical Algorithm

When evaluating a patient with testicular atrophy:

1. Measure testicular volume using Prader orchidometer (volumes <12 ml are atrophic). 1

2. Determine laterality—bilateral atrophy has far worse prognosis than unilateral. 3

3. Obtain hormonal evaluation immediately (FSH, LH, testosterone) as these reflect current function. 5

4. Perform baseline semen analysis, but recognize this reflects function from 2-3 months prior. 5

5. Repeat semen analysis in 2-3 months to assess true impact of current atrophy. 5

6. If fertility is desired and counts are declining, consider sperm cryopreservation (2-3 ejaculates) before further deterioration. 1

7. Even with severe atrophy and azoospermia, micro-TESE remains an option with 55% retrieval rates. 7