Do men with one testicle produce normal sperm?

Sperm Production in Men with One Testicle

Men with a single testicle can produce normal sperm and achieve fertility rates similar to men with two testicles, though they may show signs of compensatory hormonal changes to maintain normal sperm parameters.

Normal Sperm Production with One Testicle

• Men with a unilateral testicle (solitary testis) can produce sperm with normal parameters including concentration, motility, and morphology, allowing for fertility rates nearly equivalent to those of men with two testicles 1, 2
• The contralateral (remaining) testicle typically compensates for the missing testicle through increased hormonal stimulation, allowing for adequate sperm production 2
• Paternity rates among men with a history of unilateral cryptorchidism (undescended testicle) that was surgically corrected are nearly equivalent to those for men without cryptorchidism 1

Hormonal Adaptations in Men with One Testicle

• Men with a solitary testicle typically show compensated pituitary strain with higher serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels compared to men with bilateral testes, despite having similar testosterone levels and semen parameters 2
• The prevalence of compensated hypogonadism (high LH with normal testosterone) is significantly higher in men with a solitary testicle (28%) compared to men with bilateral testes (8.2%) 2
• This compensatory mechanism allows the remaining testicle to maintain adequate spermatogenesis despite the absence of the second testicle 2

Fertility Potential and Considerations

• While men with one testicle can produce normal sperm, they may be at higher risk for decreased fertility if the remaining testicle has any structural or functional abnormalities 1
• Men with a solitary testicle may still have sperm in the ejaculate even with FSH levels as high as 54.6 mIU/ml, whereas men with bilateral testes are uniformly azoospermic after FSH levels of 25.0 mIU/ml 2
• Normal semen parameters (normozoospermia) include sperm concentration ≥16 million/mL, total sperm number ≥39 million per ejaculate, progressive motility ≥30%, and ≥4% morphologically normal forms 1, 3

Monitoring and Management

• Men with a solitary testicle should undergo regular monitoring of hormonal status to detect any progression from compensated to overt hypogonadism 2
• Regular self-examination of the remaining testicle is important as men with a history of undescended testicle have a 3.6-7.4 times higher risk of developing testicular cancer 1
• If fertility issues arise, a comprehensive semen analysis should be performed to assess sperm parameters according to WHO reference limits 1, 3

Potential Complications and Considerations

• Long-term follow-up is recommended to evaluate any potential consequences of the compensated hormonal state that may lead to pituitary burnout and decreased testicular function over time 2
• If the solitary testicle is the result of cryptorchidism, there may be structural abnormalities in the remaining testicle that could affect fertility 1
• Men with bilateral cryptorchidism have significantly lower paternity rates (35-53%) compared to those with unilateral cryptorchidism or men without cryptorchidism 1

In conclusion, while men with one testicle face some physiological challenges, the human reproductive system demonstrates remarkable adaptability, allowing for normal sperm production and fertility in most cases, though with compensatory hormonal changes that warrant monitoring.