STUDY QUESTION
Is prior testicular torsion associated with testicular function (semen quality and reproductive hormones) in young men from the general population?

SUMMARY ANSWER
In young men from the general population, no differences in semen parameters were observed in those who had experienced testicular torsion compared to controls and observations of higher FSH and lower inhibin B were subtle.

WHAT IS KNOWN ALREADY
Testicular function may be impaired after testicular torsion, but knowledge is sparse and based on studies with small sample sizes and no control group or a less than ideal control group.

STUDY DESIGN, SIZE, DURATION
A cross-sectional population-based study was carried out including 7876 young Danish men with unknown fertility potential, examined from 1996 to 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS
All men (median age 19.0 years) had a physical examination, provided a blood and semen sample, and filled in a questionnaire including information about prior testicular torsion, birth, lifestyle and current and previous diseases. Markers of testicular function, including testis volume, semen parameters and reproductive hormones, were compared between men operated for testicular torsion and controls, using multiple linear regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE
The average participation rate was 24% for the entire study period. In total, 57 men (0.72%) were previously operated for testicular torsion (median age at surgery 13.4 years) of which five had only one remaining testicle. Men with prior testicular torsion were more often born preterm (25% versus 9.5% among controls), and they had significantly higher FSH and lower inhibin B levels, and a lower inhibin B/FSH ratio than controls in crude and adjusted models. The association was mainly driven by the subgroup of men who had undergone unilateral orchiectomy. No differences in semen parameters were observed.

LIMITATIONS, REASONS FOR CAUTION
A limitation is the retrospective self-reported information on testicular torsion. Also, results should be interpreted with caution owing to the high uncertainty of the observed differences.

WIDER IMPLICATIONS OF THE FINDINGS
Overall, the results of our study are reassuring for men who have experienced testicular torsion, especially when treated with orchiopexy, for whom reproductive hormone alterations were subtle and without obvious clinical relevance. Our study found no differences in semen parameters, but follow-up studies are needed to assess any long-term consequences for fertility.

STUDY FUNDING/COMPETING INTEREST(S)
Financial support was received from the Danish Ministry of Health; the Danish Environmental Protection Agency; the Research fund of Rigshospitalet, Copenhagen University Hospital; the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); A.P. Møller and wife Chastine Mckinney Møllers Foundation; Svend Andersens Foundation; the Research Fund of the Capital Region of Denmark; and ReproUnion (EU/Interreg). The authors have nothing to declare.