Racial differences in male fertility parameters in 2,996 men examined for infertility in a single center.

Objectives: Several studies have demonstrated racial variations in various diagnostic clinical parameters in different fields of medicine including andrology. Yet, clinical andrological diagnostic is following the lower reference values recommended by the World Health Organization irrespective of the racial descent of men. Therefore, this study aimed to investigate racial differences in hormonal and semen parameters including sperm DNA fragmentation (SDF) and seminal oxidative stress in a large group of patients from Sub-Saharan, Caucasian, Central/South Asian, Middle Eastern, North African, and Southeast Asian descent.

Methods: In a total of 2,996 infertile men, testis volume, sperm concentration, total sperm count, total and progressive motility, normal morphology, sperm vitality, SDF, oxidation-reduction potential (ORP), and standard hormones were determined and compared.

Results: Significant racial differences for various parameters including the incidence of normal ranges values in the racial groups were found. The highest mean sperm concentration had men of Central/South Asian descent (median: 38.0 × 10⁶/mL) while Southeast Asian men had the lowest (median: 22.0 × 10⁶/mL; p < 0.0001). The highest total sperm motility (median: 55.0%) was observed in Caucasian, Central/South Asian, and Southeast Asian men, while Sub-Saharan African men had the lowest (median: 45.0%; p < 0.0001). For SDF, Caucasian men had the lowest sperm DNA fragmentation (median: 16.0%) and ORP values (median: 1.3 mV/10⁶ sperm/mL) as compared to Central/South Asian men (median: 28.0%; p = 0.0263) and Southeast Asian men (median: 2.4 mV/10⁶ sperm/mL; p = 0.0045), respectively.

Conclusions: Our results show not only significant racial differences for many of the parameters investigated but also for the incidence of normal values. Therefore, it might be prudent to revisit the concept of globally standardized reference values for all men. Yet, as a limitation, the small number (53) of Caucasian men needs to be mentioned. Larger studies that include functional sperm parameters need to be conducted.