Coenzyme Q10: another biochemical alteration linked to infertility in varicocele patients?

Previously we demonstrated that coenzyme Q10 (CoQ10) is present in human seminal fluid and shows a direct correlation with seminal parameters except in patients with varicocele (VAR). We have now evaluated CoQ10 distribution in VAR, versus control subjects, in order to discover metabolic abnormalities within this condition. We studied 32 patients with VAR (11 with oligoasthenozoospermia, 13 with asthenozoospermia, and 8 with normozoospermia), and, as controls, the following groups of subjects, matched with VAR patients according to seminal parameters: 16 patients with idiopathic oligozoospermia, 11 patients with isolated asthenozoospermia, and 14 normal fertile men. CoQ10 was assayed in total seminal fluid, plasma, or cell pellet by high-performance liquid chromatography (HPLC). We found a significantly higher proportion of CoQ10 in seminal plasma in VAR; cellular CoQ10 showed an inverse correlation with sperm concentration and motility in VAR, at variance with controls. As seminal plasma ubiquinone reflects an interchange between intracellular and extracellular compartments, the different distribution in VAR patients could represent a greater sensitivity to peroxidative damage and could suggest reduced utilization for energy, which in turn could cause a defective motility even in patients with a normal cell count. These data suggest a pathophysiological role of CoQ10 in seminal plasma and a possible molecular defect in VAR.