Proposed age-stratified reference intervals of FSH derived from normozoospermic men

Objective: To demonstrate that serum follicle-stimulating hormone (FSH) in men rises with age, and to explore FSH reference intervals of age-related partitioning. Methods: Men aged 20-50 years (n=1 190) underwent semen analysis according to World Health Organization (2010) methods. Serum was frozen prior to measurement of FSH by using the Siemens ADVIA Centaur® XP immunoassay system. FSH central 95% intervals after logarithmic transformation based on age were derived from 1 037 normozoospermic men. These were then applied to oligozoospermic and azoospermic men. Men producing azoospermic semen samples were further classified as having non-obstructive azoospermia by clinical diagnostic criteria, including genetic analysis and surgical exploration. Results: Serum FSH in normozoospermic men increased with age (P Conclusions: FSH concentrations increase in men between 20-50 years, and clinical interpretation of serum FSH results in men must be made by using age-based reference intervals.