There are two general forms found in adult men who had normal hormone levels through puberty and young adulthood and who experience normal sexual development. One form, analogous to female menopause, as associated with the rapid drop of testosterone levels. Acute andropause in men is relatively uncommon, compared to acute menopause in women, because testicular function declines gradually in most men. The second form of this syndrome is more insidious since it occurs gradually. It is often confused with male midlife psychological adjustment disorders because it exactly mimics depression in midlife men.
Male hormones decline gradually.
For many men, this does not occur until their 60s or 70s but there are older where it occurs much earlier. In addition, there is proteins in the blood which bind testosterone in a biologically inactive form. These are called sex human binding proteins or globulins. As an example, there is some data suggesting that men on low fat or vegetarian diets have lower testosterone levels. The overall effect of rising sex hormone binding proteins is that there is less bio-available testosterone.