Testosterone supplementation therapy as a treatment of hypogonadism

A substantial proportion of older men (ranging from 20% of 60-year-old to 50% of 80-year-old men) have total serum testosterone levels below the normal range for younger men (1). At the age of 75 years, mean plasma testosterone levels are only 65% of levels in young adults, whereas over 25% of these men have bioavailable testosterone levels below the lowest normal limit in young adults. The interindividual variations in the plasma levels are, however, very important and a quarter of men over 75 years old have still testosterone levels within the upper quartile of values in young men (2). Many symptoms associated with aging in men, including muscle atrophy and weakness, osteoporosis, reduced sexual functioning, and increased fat mass, are similar to changes associated with testosterone deficiency in young men. These similarities suggest that testosterone supplementation may prevent or reverse the effects of aging (3), improve the general well being, sexual characteristics and behaviour of elderly men (Fig. 4, Ref. 71).