Oligozoospermia: etiology, pathogenesis, and algorithm for differential diagnostics
Abstract
Aim: to compare international and Russian epidemiological data on the causes of oligozoospermia and to develop differential diagnostics and patient management algorithm by taking into account endocrine, genetic and immunological factors. Materials and Methods. A retrospective observational study included 210 men aged 25-45 years with confirmed oligozoospermia and infertility complaints. All patients underwent semen analysis according to the World Health Organization standards (2021), blood hormone testing (follicle-stimulating hormone, luteinizing hormone, total testosterone, prolactin, thyroid-stimulating hormone, estradiol, inhibin B, anti-Müllerian hormone, 17-hydroxyprogesterone), scrotal ultrasound, as well as genetic testing (karyotyping and Y-chromosome microdeletions). The data provided by international clinical guidelines, European Association of Urology (EAU, 2024), American Urological Association/American Society for Reproductive Medicine (AUA/ASRM, 2024), publications in Russian and English retrieved from PubMed/MEDLINE, Scopus and eLibrary databases were analyzed. Results. A wide spectrum of oligozoospermia causes was identified: endocrine disorders (hypo- and hypergonadotropic hypogonadism), Klinefelter syndrome, Y-chromosome microdeletions, varicocele, and obstructive forms. The pathophysiological mechanisms of hypogonadism, the clinical significance of Klinefelter syndrome, features of Y-chromosome azoospermia factor deletions, and the role of varicocele as a potentially reversible cause of male infertility are discussed in detail. Conclusion. Differential diagnosis of oligozoospermia requires a comprehensive, stepwise approach. Incorporating repeated semen analysis, hormonal profiling, ultrasound, and genetic testing into the diagnostic algorithm enables identification of reversible causes (varicocele, hypogonadotropic hypogonadism) as well as timely diagnostics of genetic forms (Klinefelter syndrome, Y-chromosome microdeletions). This ensures a personalized therapeutic strategy and improves the effectiveness of assisted reproductive technologies.