Semen quality in healthy adolescents related to available norms

Andrological assessment during adolescence is crucial for evaluating and preventing future fertility issues, however, current semen analysis relies on adult reference ranges from the WHO Manual, lacking specific standards for adolescents. This study aimed to evaluate sperm quality in healthy adolescent boys and compare the findings with established adult norms.

Forty-four healthy adolescents aged 15-17 years, all in Tanner stage 5 of puberty, were prospectively enrolled. Exclusion criteria included genitourinary diseases or relevant medical conditions affecting future fertility. Two semen samples were collected 4 weeks apart from each participant after 3-4 days of abstinence and analyzed according to the WHO Manual (volume, sperm count, concentration, morphology, and progressive motility). Additionally, functional sperm parameters such as percentage of vital (non-apoptotic) sperm, sperm with permeable acrosome, and DNA fragmentation were assessed using flow cytometry. Abnormal findings were considered if present in both samples. We determined the frequency of pathological findings for each parameter and their frequency in the study group. We also calculated the intraindividual variability of the parameters, established a reference range of the 25th-75th percentiles for each parameter and compared the results with existing reference values for adult males.

At least one repeatedly detected abnormal standard sperm parameter was found in 16 (36.3 %) boys, while 35 (79%) showed at least one repeatedly detected abnormal functional sperm parameter. The most common pathological finding in standard semen analysis was low progressive motility in 10 (22.7 %) cases. Functional abnormalities included a low proportion of non-apoptotic sperm in 15 (34 %) and high acrosome permeability in 24 (55 %) boys. Notably, all adolescents had a normal proportion of sperm with fragmented DNA. Descriptive parameters such as sperm count, concentration, and morphology were largely normal or superior to adult reference values. Although Spearman's coefficients showed moderate parameter stability (0.53-0.60), the mean relative difference between the two analyses was high, reaching 62% for total count and 74% for concentration.

This is the first study encompassing both descriptive and functional semen parameters in healthy adolescent boys. Our findings demonstrate that, even in healthy adolescents, a single semen analysis is insufficient to accurately evaluate semen quality. A significant proportion of these healthy boys exhibited abnormal functional semen parameters, even when their descriptive parameters were within or better than adult norms. This highlights the inadequacy of adult WHO reference ranges for this age group and the need for age-specific standards to guide clinical decisions.