A team of Australian researchers set out to determine the levels of testosterone and its two bioactive metabolites—dihydrotestosterone (DHT) and estradiol (E2)—among men aged 35 to 100 living in three major Australian cities. The investigators noted several specific factors associated with the decline in these androgens and made a suggestion regarding future research.
The experts evaluated 10,904 serum samples from the men and documented serum levels of testosterone, DHT, and E2 using liquid chromatography-mass spectrometry. They also noted age, height, and weight of the study population.
The authors reported in the European Journal of Endocrinology that serum testosterone, DHT, and E2 levels declined gradually from age 35, with a more significant decrease apparent after age 80. Factors associated with reduced testosterone, DHT, and E2 included greater body weight, higher body mass index, and higher body surface area, as well as shorter stature. They suggested that future research concerning age-related declines in androgens focus on the progressive presence of other medical conditions.
In an earlier study conducted in the United States, a team at the New England Research Institutes reported a population-wide drop in testosterone levels among men in Massachusetts over a 20-year period that was not related to normal aging, health, or lifestyle factors known to have an impact on testosterone levels. The decline was reported to be 1.2 percent annually, or about 17 percent overall, from 1987 to 2004.