Seminal Homocysteine Levels in Men With Asthenozoospermia: Correlation With Sperm Parameters and Vitamin B₆ Levels

In this study, we aim to assess the seminal plasma levels of homocysteine in men with asthenozoospermia compared with normozoospermic men and to investigate their correlations with sperm parameters and seminal plasma vitamin B₆ levels. The levels of homocysteine and vitamin B₆ were measured in 108 asthenozoospermic and 64 normozoospermic semen samples. Homocysteine levels in seminal plasma were determined using high-performance liquid chromatography, whereas vitamin B₆ levels were measured by liquid chromatography-tandem mass spectrometry. The results showed that seminal plasma levels of homocysteine were significantly higher in the asthenozoospermic group than in the normozoospermic group (3.08 ± 0.320 vs. 1.23 ± 0.320  μmol/L, p < 0.0001). Notably, the receiver operating characteristic (ROC) curve analysis demonstrated that the area under the curve was 0.999 (p < 0.0001), indicating a strong diagnostic performance of seminal plasma homocysteine in distinguishing asthenozoospermic men from normozoospermic men. In addition, the cutoff value was > 1.87 μmol/L, with a specificity of 100.0% (95% CI: 94.3%-100%) and a sensitivity of 99.1% (95% CI: 94.9%-99.9%). In the normozoospermic group, there was no statistically significant association between seminal plasma levels of homocysteine and progressive motility (p = 0.675, r² = 0.00286) or total motility (p = 0.178, r² = 0.0291) of spermatozoa. However, in the asthenozoospermic group, progressive and total motility were inversely correlated with the seminal plasma levels of homocysteine (p = 0.0025, r² = 0.0827, p = 0.0048, r² = 0.0725, respectively). No significant correlation was found between homocysteine levels and sperm concentration, semen volume, age, or seminal plasma vitamin B₆ levels in either group. These findings suggest that seminal plasma levels of homocysteine are associated with impaired sperm motility and may serve as a potential biomarker for asthenozoospermia. However, further studies are needed to confirm these findings.