From the age of 30 yrs on, the (free) testosterone {(F)T} levels decrease continuously with age, mean total T level at age70yrs, being only 2/3rds of the mean level at age 25yrs, whereas mean FT level is only 40% of the mean level in young adults. However, inter-individual variations are wide and whereas at least 30% of men over age 70 yrs have clearly subnormal (F)T levels, 20% have still levels in the upper range of values in young men. Aging in males is accompanied by a series of signs and symptoms, reminiscent of androgen deficiency in young adults, such as decrease in muscle mass and strength, increase in abdominal, mainly visceral, fat with insulin resistance and atherogenic lipid profile, decrease in libido and sexual hair, osteopenia, decrease in cognitive performances, insomnia, excessive sweating and decrease in general well-being, and it is tempting to relate these symptoms to the age associated decrease in androgen levels, the more that often a significant, albeit generally weak, correlation of these symptoms with the (F)T levels is observed. Moreover, the preliminary data suggest favourable effects of androgen supplementation in the elderly.

The decrease in (F)T levels is, however, only one of the factors responsible for the signs and symptoms of the aging male which have a multifactorial origin. Hence, the diagnosis of androgen deficiency in elderly men should be based on both the clinical symptomatology and the biochemistry, i.e. decreased (F)T levels, the latter being defined, more or less arbitrary, as levels below the lowest 1% of levels in young healthy males.