Defining Reference Ranges for Serum Anti-Mullerian Hormone on a Large Cohort of Normozoospermic Adult Men Highlights New Potential Physiological Functions of AMH on FSH Secretion and Sperm Motility

Background Few studies to date have attempted to measure serum anti-Mullerian hormone (AMH) levels in adult men, and solid references ranges have not yet been defined in a large cohort. Objective In this study, we aimed, first, to establish the reference ranges for serum AMH and AMH-to-total testosterone ratio (AMH/tT) in adult males. Second, we investigated the relationship between serum AMH and both reproductive hormones and semen parameters. Methods This single-center retrospective study included 578 normozoospermic adult men. Serum AMH concentrations were determined with an automated sandwich chemiluminescent immunoassay. Results The median serum AMH was 43.5 pmol/L. The 2.5th and 97.5th percentile values for serum AMH and AMH/tT were 16.4 and 90.3 pmol/L and 0.45 and 3.43, respectively. AMH was positively correlated with inhibin B and sperm concentration and negatively correlated with age, follicle-stimulating hormone (FSH), and progressive sperm motility. Interestingly, using immunofluorescence, we documented for the first time that AMH type II receptor (AMH-R2) is expressed in ejaculated human spermatozoa and gonadotrophic cells in the postmortem pituitary gland. Conclusions We establish a new age-specific reference range for serum AMH and AMH/tT. Moreover, AMH-R2 expression in human spermatozoa and gonadotrophic cells, together with the relationship between serum AMH levels and sperm motility or mean FSH levels, highlight new potential functions of AMH in regulating sperm motility or FSH secretion in adult men.