Should I be concerned about my testicular size decrease with normal hormone levels, including Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), and a Testosterone level of 37.7 nanomoles per liter (nmol/L)?

Should You Be Concerned About Your Testicular Size and Hormone Levels?

Your hormone levels and testicular size are within normal ranges and do not warrant immediate concern, though your FSH is in the upper portion of normal, suggesting your testes are working harder to maintain adequate sperm production. 1

Understanding Your Current Status

Your hormone profile shows:

• FSH 10.3 IU/L (range 1-12.4): This is elevated within the normal range. FSH levels >7.6 IU/L are associated with some degree of testicular dysfunction, though this doesn't mean complete absence of sperm production 1
• LH 7 IU/L: Normal range, indicating your pituitary is appropriately signaling your testes 1
• Testosterone 37.7 nmol/L: This is excellent—well above the threshold for hypogonadism (typically <10.4 nmol/L or <300 ng/dL) 2
• Testicular volume 10 ml bilaterally: This is below the normal adult range of 15-25 ml, which correlates with your elevated FSH 3

What This Pattern Means

Your hormone pattern suggests mild primary testicular dysfunction with compensated testosterone production. 1 The elevated FSH indicates your pituitary is producing more FSH to stimulate your smaller testes to maintain adequate function 3. However, your normal LH and robust testosterone levels indicate your Leydig cells (testosterone-producing cells) are functioning well 1.

The combination of:

• Mildly elevated FSH
• Normal LH
• Normal-to-high testosterone
• Small testicular volume (10 ml)

...is most consistent with oligospermia (reduced sperm count) rather than azoospermia (complete absence of sperm) 1. Studies show testicular size correlates strongly with FSH levels and sperm production, with impairment typically occurring when testes are smaller than 14 ml 3.

Essential Next Steps

1. Confirm Your Fertility Status

Obtain at least two semen analyses separated by 2-3 months to determine your actual sperm production 1. Single analyses can be misleading due to natural variability, and FSH levels alone cannot definitively predict fertility status 1.

2. Investigate Reversible Causes

Before assuming this is permanent testicular dysfunction, evaluate for:

• Thyroid function (TSH, free T4): Thyroid disorders commonly disrupt the hypothalamic-pituitary-gonadal axis and can elevate FSH 1
• Prolactin levels: Hyperprolactinemia can disrupt gonadotropin secretion 1
• Metabolic factors: Obesity (BMI >25) and metabolic stress can affect gonadotropin levels 1
• Varicocele on physical examination: Correction of palpable varicoceles can improve semen quality 1

3. Consider Genetic Testing (If Semen Analysis Shows Severe Oligospermia)

If your sperm count is <5 million/mL, obtain:

• Karyotype analysis to exclude Klinefelter syndrome (47,XXY) 1
• Y-chromosome microdeletion testing (AZFa, AZFb, AZFc regions) if sperm concentration is <1 million/mL 1

Critical Pitfalls to Avoid

Never Start Testosterone Therapy If You Want to Preserve Fertility

Exogenous testosterone will completely suppress your FSH and LH through negative feedback, eliminating sperm production and potentially causing azoospermia that can take months to years to recover 1. Your current testosterone level of 37.7 nmol/L is excellent and requires no supplementation 2.

Don't Assume Testicular Atrophy Without Objective Measurement

Perceived testicular shrinkage may not reflect actual volume changes 1. Your 10 ml bilateral volume, while below average, is not severely atrophic. Repeat measurement in 6-12 months can establish whether progressive atrophy is occurring 1.

Prognosis and Fertility Considerations

Up to 50% of men with non-obstructive azoospermia and elevated FSH still have retrievable sperm 1. Given your FSH is only mildly elevated and your testosterone is robust, you are much more likely to have oligospermia with reasonable fertility potential than complete testicular failure 1.

If semen analysis confirms severe oligospermia:

• Assisted reproductive technology (IVF/ICSI) offers superior pregnancy rates compared to empiric hormonal therapy 1
• Consider sperm cryopreservation if follow-up analyses show declining trends, as men with elevated FSH and small testicular volumes are at risk for progressive spermatogenic failure 1
• Microsurgical testicular sperm extraction (micro-TESE) achieves 40-60% sperm retrieval rates even in non-obstructive azoospermia with elevated FSH 1

Monitoring Strategy

Recheck FSH, LH, testosterone, and thyroid function after 3-6 months of metabolic optimization (if applicable) 1. Weight normalization and correction of thyroid or metabolic disturbances may improve hormonal parameters in some cases 1.