Relationship between blood and seminal fluid zinc levels and semen parameters among Nigerian men

Background: Zinc plays an important role in testicular development, spermatogenesis and sperm motility via its antioxidant properties in scanvenging reactive oxygen species. Objectives: This study sets out to determine the correlation of blood and seminal fluid zinc levels and semen parameters in Nigerian men with normal and abnormal semen parameters who were seen for infertility. Methods: A prospective case-control study of eighty five men with abnormal semen parameters (cases) and equal number with normozoospermia (controls) enrolled from the Institute of Fertility Medicine and the gynaecological outpatient clinic was carried out. The cases were further sub-grouped as oligozoospermic (n=64), asthenozoospermic (n=13) and azoospermic (n=8). Blood and seminal fluid concentrations of zinc were determined by microwave plasma-atomic emission spectrophotometer. Results: The median zinc concentrations in blood and seminal seminal fluid were significantly lower in the cases compared with the controls; 1.7 μmol/L(IQR 0.6,2.7) versus 3.2 μmol/L (IQR 1.6,5.2), p<0.001 and 9.0 μmol/L (IQR 6.1,11.0) versus 19.4 μmol/L (IQR 14.0,25.5), p<0.001 respectively. Blood zinc levels showed a significant positive correlation with sperm count (r=0.311 p=0.012), progressive motility (r=0.252 p= 0.045) and total motility (r=0.285 p=0.022) in the oligozoospermic men. Seminal fluid zinc level however was significantly correlated only with progressive sperm motility (r=0.251 p=0.045) in the oligozoospermic men. Conclusion: This study revealed that blood and seminal plasma zinc levels were significantly lower in men with abnormal semen parameters compared with normal controls. In oligozoospermic men, blood zinc levels were significantly positively correlated with semen parameters while the seminal fluid zinc levels showed significant positive correlation only with progressive motility.