Your Testicular Function is Excellent Despite Smaller Size
Based on your hormone levels and sperm concentration of 40 million/mL, your testes are functioning normally and you should not be concerned about the 10 mL bilateral volume. 1
Understanding Your Results
Your testicular volumes of 10 mL fall just below the 12 mL threshold that defines the lower limit of normal, but this measurement alone does not determine fertility or testicular health. 1 What matters most is the functional output of your testes, which is clearly normal based on your laboratory results.
Your Hormone Profile Indicates Normal Function
FSH 9.5 IU/L (range 1–12.4): This level is in the upper-normal range but does not indicate testicular failure. FSH levels >7.6 IU/L suggest the testes are working harder to maintain sperm production, but your actual sperm output proves they are succeeding. 1, 2
LH 7.2 IU/L (range 1–8.6): Normal LH argues against primary testicular failure and indicates your Leydig cells are responding appropriately to produce testosterone. 1
Testosterone 43 nmol/L: This level is in the high-normal to elevated range, confirming excellent Leydig cell function despite smaller testicular size. 1
Sperm concentration 40 million/mL: This far exceeds the World Health Organization lower reference limit of 16 million/mL and places you well within the normal fertile range. 1, 3
Why Size Doesn't Always Predict Function
Testicular volume strongly correlates with sperm production on average, but individual variation exists. 1, 4, 5 Research shows that:
Mean sperm density enters the oligozoospermic range when testicular volume drops below 10 mL per testis (or total volume <20 mL by ultrasound). 4, 5
Your sperm concentration of 40 million/mL demonstrates that your 10 mL testes are producing sperm at a rate consistent with larger testes in other men. 4, 5
The combination of borderline-small testes with upper-normal FSH indicates your pituitary is providing extra stimulation to compensate, and this compensation is working effectively. 1
What You Should Monitor
Although your current function is normal, the combination of 10 mL testicular volume and FSH in the upper-normal range indicates reduced testicular reserve—meaning you have less capacity to compensate if additional stressors occur. 1
Essential Follow-Up Actions
Repeat semen analysis every 6–12 months to detect any early decline in sperm parameters, as single analyses can be misleading due to natural variability. 1, 2
Recheck FSH, LH, and testosterone annually to monitor for progression. If FSH rises significantly above 12 IU/L or sperm concentration drops below 20 million/mL, further evaluation would be warranted. 1
Physical examination by a urologist or male fertility specialist to assess for varicocele (dilated scrotal veins), testicular consistency, and any asymmetry >2 mL or 20% between sides, as these findings may require ultrasound evaluation. 1
Critical Pitfalls to Avoid
Never use exogenous testosterone or anabolic steroids if you desire current or future fertility. These agents completely suppress FSH and LH through negative feedback, causing azoospermia (zero sperm) that can take months to years to recover—even after stopping. 1, 2, 6
Avoid chronic opioid use, which suppresses GnRH secretion and can cause secondary hypogonadism and testicular atrophy. 1
Optimize modifiable factors: smoking cessation, maintaining healthy body weight (BMI <25), minimizing heat exposure to the testes (avoid hot tubs, saunas, tight underwear), and treating any underlying metabolic or thyroid disorders. 1, 6
When to Seek Further Evaluation
You should pursue additional workup only if:
Sperm concentration drops below 15 million/mL on repeat testing. 1
FSH rises above 12–15 IU/L, indicating worsening testicular reserve. 1
You develop a palpable testicular mass, rapid testicular shrinkage, or pain. 1
You have a history of cryptorchidism (undescended testes), which substantially increases the risk of testicular cancer and would mandate closer surveillance and possible testicular biopsy if you are under age 30–40 years. 1, 7
Fertility Considerations
Your current sperm concentration of 40 million/mL provides excellent natural conception potential. 1 If you are planning to have children:
Time to conception depends primarily on your female partner's age, not your sperm count at this level. Couples with a female partner under 30 years have a >90% chance of achieving pregnancy within 2–3 years of trying. 6
Consider sperm cryopreservation (banking 2–3 ejaculates) if follow-up testing shows declining parameters, especially if sperm concentration approaches 20 million/mL or drops below 5 million/mL. Once azoospermia develops, even microsurgical testicular sperm extraction (micro-TESE) only achieves 40–50% sperm retrieval rates. 1, 6
Avoid delaying fertility goals unnecessarily, as your reduced testicular reserve means you are at higher risk for progressive spermatogenic decline compared to men with larger testes. 1
Bottom Line
Your testes are small but functioning excellently. The proof is in your sperm count and hormone levels, not the volume measurement. Continue monitoring as outlined above, avoid gonadotoxic exposures, and pursue fertility goals without delay if children are desired. 1, 2