Does Testosterone Level Affect Semen Volume?
Testosterone levels have minimal to no direct effect on semen volume in men with normal reproductive anatomy, as semen volume is primarily determined by prostate and seminal vesicle secretions, which are regulated by dihydrotestosterone (DHT) rather than testosterone itself. 1
The Physiology of Semen Volume
- Semen volume is predominantly composed of secretions from the prostate gland and seminal vesicles, not from testicular or epididymal sources 1
- DHT, not testosterone, is the primary androgen regulating prostate and seminal vesicle development and function 1
- Men with 5-alpha-reductase-2 deficiency (who cannot convert testosterone to DHT) demonstrate extremely low semen volumes (range <0.05 to 1.0 mL) despite having normal testosterone levels, confirming that DHT—not testosterone—controls semen volume 1
Clinical Evidence on Testosterone and Semen Parameters
In men with total sperm counts >5 million undergoing IVF evaluation, low total testosterone (<264 ng/dL) showed no significant association with semen volume (3.2 ± 1.79 vs. 3.23 ± 1.64 mL, p = 0.87) 2. Multivariable regression analysis confirmed that low testosterone and free testosterone levels had no significant effect on semen volume (coefficient: 3.94, p = 0.53) 2.
The 2024 AUA/ASRM guidelines identify finasteride 5 mg/day (a 5-alpha-reductase inhibitor that blocks DHT production) as associated with reduced semen volume, while noting that evidence for 1 mg/day remains inconclusive 3. This further supports DHT's role rather than testosterone's role in determining semen volume.
The Critical Distinction: Exogenous vs. Endogenous Testosterone
A critical pitfall: exogenous testosterone therapy suppresses spermatogenesis and can cause oligospermia or azoospermia through suppression of gonadotropin secretion 4, 3. The FDA label for intramuscular testosterone explicitly lists oligospermia as an adverse reaction occurring at high dosages 4.
- The NCCN guidelines specifically warn that exogenous testosterone should not be prescribed to men trying to conceive because it causes short-term suppression of sperm production 3
- This effect occurs through hypothalamic-pituitary suppression, not through direct effects on semen volume 5
Seminal Plasma Testosterone: A Different Story
While serum testosterone doesn't significantly affect semen volume, seminal vesicle fluid testosterone concentration may correlate with other aspects of reproductive function 6. However, this represents local androgen metabolism rather than systemic testosterone's effect on volume 7.
Clinical Implications
When evaluating low semen volume (<1.5 mL), clinicians should suspect ejaculatory duct obstruction rather than testosterone deficiency 3. The 2024 AUA/ASRM guidelines recommend considering transrectal ultrasound or pelvic MRI in males with semen analysis suggestive of ejaculatory duct obstruction (acidic, azoospermic semen with volume <1.4 mL) 3.
Other factors that actually influence semen volume include:
- Hydration status (general medical knowledge)
- Ejaculatory frequency and abstinence period (general medical knowledge)
- Obesity and metabolic factors, which show associations with decreased ejaculate volume through mechanisms unrelated to testosterone 3, 5
- Medications affecting DHT production (finasteride) 3