[Pharmwaste] Men's testosterone levels declined in last 20 years

[DeBiasi,Deborah]

Men's testosterone levels declined in last 20 years
Tue Oct 31, 2006 2:23 PM ET



By Anne Harding

NEW YORK (Reuters Health) - A new study has found a "substantial" drop
in U.S. men's testosterone levels since the 1980s, but the reasons for
the decline remain unclear. This trend also does not appear to be
related to age.

The average levels of the male hormone dropped by 1 percent a year, Dr.
Thomas Travison and colleagues from the New England Research Institutes
in Watertown, Massachusetts, found. This means that, for example, a
65-year-old man in 2002 would have testosterone levels 15 percent lower
than those of a 65-year-old in 1987. This also means that a greater
proportion of men in 2002 would have had below-normal testosterone
levels than in 1987.

"The entire population is shifting somewhat downward we think," Travison
told Reuters Health. "We're counting on other studies to confirm this."

Travison and his team analyzed data from the Massachusetts Male Aging
Study, a long-term investigation of aging in about 1,700 Boston-area
men. Data from the men were collected for three time intervals:
1987-1989, 1995-1997, and 2002-2004.

While a man's testosterone level will fall steadily as he ages, the
researchers observed a speedier decline in average testosterone levels
than would have been expected with aging alone.

They hypothesized that the rising prevalence of obesity as well as the
sharp decline in cigarette smoking might help explain their findings,
given that testosterone levels are lower among overweight people and
smoking increases testosterone levels. But these factors accounted for
only a small percentage of the observed difference.

It's likely that some sort of environmental exposure is responsible for
the testosterone decline, Travison said, although he said attempting to
explain what this might be based on the current findings would be "pure
conjecture."

The researchers used body mass index, the ratio of height to weight, to
estimate obesity levels, he noted, but this is not a very accurate way
to gauge the real adiposity, or fat content of the body, so it's
possible that obesity might be more of a factor than it appears in this
analysis.

"I think like most things that are complex, it's likely that there is no
one cause," he said.

SOURCE: Journal of Clinical Endocrinology and Metabolism, January 2007.

 

Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
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