Evaluation of the serum zinc concentration in male infertility patients: an analysis of 2010 cases

Zinc is an important trace element, and its importance for male infertility has been reported. The aim of the study was to assess whether the serum zinc concentrations were related to semen quality in male infertility patients. In 2010 subjects who consulted at our male infertility clinic between November 2018 and May 2021, serum zinc concentrations were assessed along with age, sperm concentration, sperm motility, endocrine panel, and body mass index (BMI). A normal zinc concentration was observed in 1069 (53.2%), subclinical deficiency in 845 (42.0%), and deficiency in 79 subjects (3.9%). On the other hand, high a zinc level was observed in only 17 subjects (0.9%). The serum zinc concentration did not relate with age, sperm concentration, sperm motility, luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, and body mass index (BMI). However, normozoospermic subjects showed significantly higher zinc concentrations than among azoospermic (included non-obstructive; NOA and obstructive; OA) and cryptozoospermic patients. Furthermore, the zinc concentration was lower in NOA subjects when comparing to oligozoospermia and/or asthenozoospermia. An association between zinc concentration and semen analysis remained unclear. This study was cross-sectional and retrospective, however, this is a largest investigation of the zinc concentration during reproductive life span in Japan. Further accumulation of cases are required to further examine the potential relationship between zinc concentration and semen quality.