Persistence of fertility despite semen alterations in a pinealectomised patient treated with melatonin.

OBJECTIVES: Little is known about the effect of chronic melatonin treatment on human reproductive function. We report here on the effect of 10 months treatment with a controlled-release melatonin preparation (Circadin®, 2 mg) on spermatogenesis and gonadotropic hormone status in a pinealectomised patient whose melatonin secretion was abolished.

METHODS: Semen analysis, hormone (Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), inhibin B, prolactin, testosterone and estradiol) and Sex Hormone-Binding Globulin (SHB G) concentrations were determined before and at the end of 4 and 10 months of, treatment.

RESULTS: At the end of treatment, testosterone, sex hormone-binding globulin, prolactin and inhibin B levels did not display significant variation with time, whereas FSH and LH levels showed a tendency to a decrease, but remained in the normal range. Sperm concentration and total spermatozoa count dropped below the lower limit of the reference range during melatonin treatment, whereas motility and normal form percentages remained in the normal range. Fertility was preserved, since the patient's wife became pregnant during month 10 of melatonin treatment and gave birth to a healthy female baby.

CONCLUSIONS: this isolated clinical observation shows that more investigations in large patient series are needed to document possible side-effects of melatonin administration on male reproductive function. One should therefore be cautious about melatonin prescription for circadian rhythm sleep disorders in young males.