Abstract
F2-isoprostanes (F2-IsoPs), byproducts of arachidonic acid oxidation, are one of the most reliable indices for assessing lipid peroxidation in vivo. This study aimed at evaluating the seminal F2-IsoP level in 147 patients with different reproductive conditions (varicocele, urogenital infection, idiopathic infertility) and 45 fertile controls to establish a cut-off value discriminating physiological and pathological ranges. Semen analyses were performed following WHO guidelines; F2-IsoP levels were measured by gas chromatography/negative-ion chemical ionization tandem mass spectrometry. Considering the whole group of patients, F2-IsoPs correlated negatively with normal morphology (r = -0.283, p < 0.01), viability (r = -0.245, p < 0.01), total progressive motility (r = -0.309, p < 0.01) and rapid motility (r = -0.535, p < 0.01). The area under the ROC curve for F2-IsoP levels was 0.839, indicating a good performance of the test; the Youden index showed a cut-off value of 29.96 ng/mL. Fertile men (except one) were distributed in the group of patients with F2-IsoP level < 29.96 ng/mL. Varicocele and urogenital infection groups showed the highest levels of F2-IsoPs in semen. For the first time, a cut-off for F2-IsoPs is identified in human semen. It allows discriminating different male infertility conditions by the semen F2-IsoP amounts, as an additional parameter for clinical evaluation.