March 8, 2015 For male senior citizens age 70 and older, decreased
sexual activity and desire may be the cause, not an effect, of low
testosterone level, according to research presented yesterday at the
Endocrine Society meeting in San Diego.
"We found that over two years, men
with declining serum concentrations of testosterone were more likely to
develop a significant decrease in their sexual activity and sexual
desire, ," said lead study author Benjumin Hsu, MPH, PhD candidate in
the School of Public Health and the ANZAC Research Institute of the
University of Sydney in New South Wales, Australia.
In older men, decreased sexual
activity and desire may be a cause - not an effect - of low circulating
Whether decreasing sexual function
is a cause or an effect of reduced androgen status in older men, or
whether some other age-related factor may be involved, has not been clear.
To explore the relationship between
declining reproductive hormones and decreasing sexual function in older
men, Hsu and his colleagues assessed men 70 years of age and above in
Sydney, Australia, who took part in the Concord Health and Ageing in Men
Project (CHAMP). The researchers tested the men at baseline (n=1,705)
and again two years later (n=1,367).
At both visits, the participants
answered questions about their sexual functions, including,
● "How often are you able to get and keep an erection that is firm
enough for satisfactory sexual activity?";
● "How many times over the last month have you had sexual activity
(including intercourse and masturbation) reaching ejaculation?"; and,
● "How much desire for sex do you have now, compared with when you
At both visits the researchers
also measured the men's serum testosterone, dihydrotestosterone (DHT),
estradiol (E2), and estrone (E1) by liquid chromatography-tandem mass
spectrometry; and they measured the men's sex hormone-binding globulin (SHBG),
luteinizing hormone (LH), and follicle-stimulating hormone (FSH) by
Over two years, baseline serum
testosterone, DHT, E2 and E1 did not predict decline in sexual activity,
sexual desire and erectile function.
By contrast, the decline in
testosterone (but not in DHT, E2 or E1) over time, though less than 10%,
was strongly related to decreased sexual activity and desire, but not to
The National Health and Medical Research Council,
Sydney Medical School Foundation and Ageing and Alzheimer's
Institute funded the CHAMP study.
For every one standard deviation drop in testosterone from baseline
to follow-up, the adjusted odds ratio of further decline in sexual
activity was 1.23.
The decline in testosterone was strikingly
small, the researchers noted, at less than 10 percent. Declines in
estrogen were also associated with declines in sexual activity.
Founded in 1916, the Endocrine
Society is the world's oldest, largest and most active organization
devoted to research on hormones and the clinical practice of
endocrinology. The Endocrine Society is based in Washington, DC. To
learn more about the Society and the field of endocrinology, visit
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