There is a progressive decline in testosterone production in men with age. These changes can be dramatic, such that 50% of men >60 years old have low levels of testosterone. Although the rate of decline varies widely, a general rule of thumb is that testosterone levels decrease about 1% yearly after age 50.
Despite the fact that it is not as rapid a drop in hormones as women get with menopause, it certainly is just as real. This has been termed male menopause, male climacteric, andropause, or more appropriately, partial androgen deficiency in the aging male (PADAM).
Serum testosterone levels in men fall progressively from the third decade to the end of life, mainly due to a decline in the cells in the testis that make the hormone (Leydig cells). This decline may also be due to changes in hormones (GnRH, LH) and proteins (SHBG, albumin) that regulate testosterone production.
