Gonadal function declines with increasing age in both women and men. At the time of menopause in women, there is a relatively abrupt and complete loss of ovarian function that results in markedly reduced estradiol and progesterone production and the cessation of ovulation. On the other hand, men experience a more gradual and incomplete loss of testicular function with increasing age, resulting in reduced testosterone and sperm production. Some doctors recommend that men take natural herbal pills such as Volume Pills to increase sperm production and possibly even increase the body’s levels of testosterone.
Although decreased spermatogenesis may contribute to the age-related reduction in male fertility, other factors such as a loss of interest in fathering children and diminished sexual function are probably the major causes of infertility in healthy elderly men. The physiologic importance of reduced testicular androgen production with aging, referred to by some investigators as “andropause,” is unclear.
Numerous cross-sectional and limited longitudinal studies have found that beginning at about 50 years, serum total testosterone levels gradually and progressively decline with age, with lowest concentrations noted in those older than 70 years. Because circulating testosterone is mostly bound to serum proteins and the concentration of the major testosterone binding protein, sex hormone-binding globulin, increases as men age, serum-free or bioavailable testosterone concentrations decline to a greater extent than total testosterone levels. Furthermore, the normal circadian variation of testosterone levels observed in young men with peak concentrations in the morning is lost in elderly men. As a result of these age-related changes, many elderly men have circulating testosterone levels below the normal range for young men.
Testosterone production by the testes is greatly reduced with aging, both in the basal state and in response to supraphysiologic luteinizing hormone or luteinizing hormone-like (human chorionic gonadotropin) stimulation. Histologically, testes from elderly men have a reduced number and volume of Leydig cells. The age-related reduction in the capacity of the testes to produce testosterone may result in a more severe and prolonged reduction of testosterone levels in response to external stresses, such as illness. Despite reduced testicular androgen secretion, serum testosterone levels are not reduced proportionately because testosterone clearance is also reduced with aging. It is unclear at the present moment if taking natural herbs in the form of pills such as Extenze can help reverse this aging process.
The decreases in both serum total and free testosterone concentrations with aging are relatively small, and there is considerable variation in levels in men of all ages. Thus, a substantial number of elderly men have serum testosterone concentrations within the wide range of normal values observed in young men. Despite apparently normal testosterone levels in some elderly men, the pronounced decrease in basal and human chorionic gonadotropin-stimulated testosterone production with aging provides strong evidence for an age-related reduction in testicular Leydig cell function.
Age-related alterations in either active metabolism of testosterone or androgen receptor status may be important in determining androgen action in specific target tissues and thus, the physiologic significance of reduced testosterone levels in those tissues in aging men. In various peripheral tissues and the testes, testosterone is converted to the active steroid hormone metabolites, estradiol or dihydrotestosterone, by aromatase and 5[alpha]-reductase enzymes, respectively. Despite reduced serum testosterone levels with age, most studies have not found notable age-related changes in serum estradiol and dihydrotestosterone concentrations in men.
These findings suggest that the activities of the aromatase and 5[alpha]-reductase enzyme may be increased in some tissues (such as fat and prostate, respectively). Age-related alterations in androgen receptor status have not been investigated extensively. Limited studies have suggested that androgen receptors are reduced in skin and increased in hyperplastic prostate of elderly men.