Melatonin is a hormone produced by the pineal gland. There is much controversy about its relationship to the male reproductive process. In this study, seminal plasma as well as the serum melatonin levels were studied in different infertile male groups and were correlated with their semen parameters and hormonal levels. One hundred twenty male cases subdivided into six equal groups were consecutively included; fertile normozoospermic men, oligoasthenozoospermia (OA), OA with leucocytospermia, OA with varicocele, non-obstructive azoospermia (NOA) with high serum follicle stimulating hormone (FSH) and NOA with normal FSH. Semen analysis, estimation of melatonin, FSH, testosterone (T) and prolactin (PRL) hormone was carried out. Mean level of serum melatonin was higher than its corresponding seminal concentrations in all investigated groups with a positive correlation between their levels (r = 0.532, p = 0.01). Serum and seminal plasma melatonin levels in all infertile groups were reduced significantly compared with their levels in the fertile group. The lowest concentrations were in OA with leucocytospermia group. Melatonin in both serum and semen demonstrated significant correlation with sperm motility (r = 607, 0.623 respectively, p = 0.01). Serum melatonin correlated positively with serum PRL (r = 0.611, p = 0.01). It may be concluded that melatonin may be involved in the modulation of reproductive neuroendocrine axis in male infertility. Also, low levels of melatonin in semen were observed in infertile groups having reduced sperm motility, leucocytospermia, varicocele and NOA.

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Zusammenfassung Lactat‐ und Pyruvat‐Werte in der Vena testicularis von subfertilen Männern als Test für die Theorie der vorhandenen Hypoxie Um die These von der testikulären Hypoxie bei subfertilen Männern mit Varikocele zu überprüfen wurden die Blutwerte von Lactat und Pyruvat aus der Vena testicularis mit denen einer Kontrollgruppe verglichen. Statistisch ergab sich ein niedrigerer Mittelwert für Lactat und Pyruvat bei den Varikocele‐Patienten. Daraus wird die Schlußfolgerung gezogen, daß bei Varikocele keine Akkumulation von Milchsäure erfolgt und daß damit eine Hypoxie ausgeschlossen werden kann. Als die Mittelwerte der Konzentrationen für Lactat und Pyruvat in der Vena testicularis miteinander korreliert wurden, deutete sich an, daß bei Vorhandensein einer Varikocele eine gestörte Glykolyse besteht, die dem Stadium der Pyruvatbildung vorhergeht.