ABSTRACT
INTERPRETATION OF SEMEN PARAMETERS AND FUNCTION IN AGING MALES Studies on semen parameters so far were inconsistent: No changes of semen volumes were observed between men younger then 37 years and those older than 60 years (12), while Ng et al. (13) revealed significantly different seminal volumes between young and old men (Table 1). Because of reduced semen volumes, the sperm concentrations were increased in older men, while total sperm numbers were reduced. Moreover, significantly increased follicle stimulating hormone serum levels could be observed in older men, reflecting to some extent testicular spermatogenic function (14). Inhibin B as a possible marker for spermatogenesis shows a moderate but significant decrease reflecting the aging process that possibly affects spermatogenesis (15). Concerning sperm motility, a significant decrease is observed with increasing age as well as decreased normal sperm morphology (Fig. 1) (16-18). For sperm morphology, an increasing decline of normally formed spermatozoa can be observed with a percentage of 0.2% to 0.9% per year (16,19). In old men with normozoospermia, a reduction of the percentage of progressively motile sperm was observed (20). Decreased sperm motility may be a result of increased abstinence time with aging because of reduced frequency of cohabitation or masturbation (21). However, Eskenazi et al. (22) showed in a sample of healthy men that semen volume and sperm motility decrease continuously between 22 and 80 years of age with no evidence of a threshold. Recently, Hellstrom et al. (23) demonstrated in a screening population of 1174 men aged 45 to 80 (mean 52.9 years), showing up for participation in a study for erectile dysfunction treatment that the normal WHO criteria for semen analysis were met only by 46% of the study population (24). Moreover, they demonstrated a significant decline of the median semen volume, sperm motility, and morphology (Fig. 2) (23).
