BACKGROUND: Present knowledge on the impact of varicoceles on testicular function is largely based on studies of subfertile and infertile men, making it difficult to extrapolate the impact of varicocele on the general population.

OBJECTIVE: To describe associations between varicocele and testicular function assessed by semen analysis and reproductive hormones in men from the general population.

DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional multicentre study of 7035 young men, median age 19 yr, from the general population in six European countries (Denmark, Finland, Germany, Estonia, Latvia, and Lithuania) were investigated from 1996 to 2010.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We analysed results from physical examination, conventional semen variables, and serum reproductive hormones using multivariable regression analyses.

RESULTS AND LIMITATIONS: A total of 1102 (15.7%) had grade 1-3 varicocele. Increasing varicocele grade was associated with poorer semen quality, even in grade 1 varicocele. In grade 3 varicocele, sperm concentration was less than half of that in men with no varicocele. Presence of varicocele was also associated with higher serum levels of follicle-stimulating hormone, lower inhibin B, and higher levels of luteinising hormone; testosterone and free testosterone were not significantly different between men with and without varicocele. This study cannot draw a conclusion on the progressiveness of varicocele or the effect of treatment.

CONCLUSIONS: We demonstrated an adverse effect of increasing grade of varicocele on testicular function in men not selected due to fertility status.

PATIENT SUMMARY: The presence and increasing grade of varicocele is adversely associated with semen quality and reproductive hormone levels in young men from the general population.