Can Men with Smaller-Than-Average Testicles Have Normal Testosterone and Father Children?
Yes, men with smaller-than-average testicles can absolutely have normal testosterone levels and successfully father children, though testicular size does correlate with sperm production parameters and smaller testes may indicate increased risk for fertility issues in some cases. 1
Understanding the Relationship Between Testicular Size and Function
The relationship between testicular size and reproductive function is not absolute—it exists on a spectrum:
- Testicular size correlates most strongly with FSH levels, total sperm count, and sperm concentration, but this correlation is not deterministic 1
- Men with testicular volumes as low as 14 mL can still produce adequate sperm, though both sperm quantity and quality tend to decline below this threshold 1
- A slightly smaller testis with normal vascularity and normal ultrasound structure does not indicate permanent infertility and should be reassuring 2
Clinical Examples Supporting Normal Function with Smaller Testes
Several clinical scenarios demonstrate that smaller testicular size does not preclude normal reproductive function:
- Men with unilateral cryptorchidism (one undescended testicle) have paternity rates nearly equivalent to men without cryptorchidism, despite the affected testis often being smaller 2
- Men with a single testicle can produce sperm with normal concentration, motility, and morphology, allowing for fertility rates nearly equivalent to those with two testicles 3
- Even in bilateral cryptorchidism where both testes may be smaller, paternity rates of 35-53% are still achieved 2
When Smaller Testes Indicate Dysfunction
Testicular size becomes clinically concerning when combined with other abnormalities:
- Severe atrophy (typically <12 mL volume) combined with elevated FSH (>7.6 IU/L) indicates spermatogenic failure 2
- Non-homogeneous testicular architecture on ultrasound, representing testicular dysgenesis, suggests irreversible damage 2
- Testicular atrophy from mumps orchitis, trauma, torsion, or chronic conditions (liver cirrhosis, hemochromatosis) indicates pathologic dysfunction 4
Testosterone Production vs. Sperm Production
It's critical to understand that testosterone production and sperm production are partially independent:
- Low testosterone levels in subfertile men with total sperm counts >5 million showed no significant negative impact on semen parameters (volume, count, motility, morphology) 5
- Testosterone is produced by Leydig cells, while sperm production occurs in seminiferous tubules—these can be affected independently 6
- Men with obesity and low sex hormone-binding globulin may have low total testosterone but normal free testosterone levels 6
Assessment Approach for Men with Smaller Testes
When evaluating a man with smaller-than-average testicles:
- Perform two properly conducted semen analyses at least one month apart to assess actual fertility status, as ultrasound and size measurements are suggestive but not diagnostic 2
- Measure morning (8-10 AM) total testosterone, free testosterone by equilibrium dialysis, FSH, LH, and sex hormone-binding globulin 6
- Physical examination should assess testicular consistency, symmetry, and presence of varicocele 6
- FSH >7.6 IU/L with testicular atrophy suggests non-obstructive azoospermia, though up to 50% of these men may still have retrievable sperm 7
Important Caveats
- FSH levels and testicular volume do not accurately predict spermatogenesis in all cases—men with maturation arrest can have normal FSH and testicular volume despite severe spermatogenic dysfunction 2
- Testicular size measurement is helpful for rapid assessment during initial examination but cannot definitively determine fertility potential 1
- Regular self-examination is important as men with history of undescended testicle have 3.6-7.4 times higher risk of testicular cancer 3