From the Guidelines
Inhibin B is a crucial biomarker for assessing male fertility, particularly for evaluating testicular function and spermatogenesis, with low levels indicating impaired spermatogenesis and associated with male infertility, as supported by the most recent guidelines 1. The role of Inhibin B in male infertility is significant, as it directly reflects Sertoli cell function and spermatogenic activity, making it a more specific marker of testicular function compared to FSH.
- Inhibin B levels can help distinguish between different causes of azoospermia, such as Sertoli cell-only syndrome and maturation arrest.
- Normal inhibin B levels generally range from 100-400 pg/mL in adult men, with levels below 80 pg/mL often correlating with abnormal sperm production.
- Testing for inhibin B is particularly useful when evaluating non-obstructive azoospermia, as it can help determine the likelihood of successful sperm retrieval techniques like TESE.
- Inhibin B testing is often combined with other hormonal assessments (FSH, LH, testosterone) and semen analysis for a comprehensive fertility evaluation, providing clinicians with valuable information for diagnosis and treatment planning in male infertility cases, as recommended by recent guidelines 1.
- The most recent guidelines emphasize the importance of inhibin B in evaluating male infertility, particularly in cases of non-obstructive azoospermia, and recommend its use in combination with other diagnostic tools to guide treatment decisions 1.
From the Research
Role of Inhibin B in Male Infertility
- Inhibin B is a dimeric gonadal glycoprotein that inhibits the production and/or secretion of follicle stimulating hormone (FSH) 2, 3.
- It is the physiologically important form of inhibin in men and is produced exclusively by the testis, predominantly by the Sertoli cells 2, 3.
- Inhibin B controls FSH secretion via a negative feedback mechanism and its production depends on FSH and spermatogenic status 3.
Relationship between Inhibin B and Spermatogenesis
- Serum inhibin B levels are strongly positively correlated with testicular volume and sperm counts 2, 4, 5.
- Inhibin B is a valuable index of spermatogenesis, and its measurement can provide useful information on spermatogenesis 3.
- A positive correlation exists between inhibin B levels and sperm counts, making it a potential non-invasive predictor of spermatogenesis 6.
Clinical Relevance of Inhibin B in Male Infertility
- Inhibin B levels can be used to evaluate male infertility, with a sensitivity of 75% and specificity of 93.1% 6.
- The measurement of serum inhibin B levels can help avoid unnecessary testicular biopsies and is a useful diagnostic marker of male infertility 6.
- However, the prediction of the quality of spermatogenesis based on inhibin B levels is not superior to that of FSH levels 5.