Quellen
: Institute of Medicine (IOM), The Food and Drug
Administration FDA and Harvard Medical School
Testosteron-Therapie
bei gesunden älteren Männern wirkungslos
?
Allein
in den USA erhielten im Jahr 2002 rund 800.000 Männer
- oft auf deren ausdrücklichen Wunsch - von
ihren Ärzten das männliche Sexualhormon
Testosteron verordnet - meist in Form von Testosteron-Gel.
Jetzt legte eine hochrangige Untersuchergruppe die
Resultate einer kritischen Durchleuchtung der vorliegenden
wissenschaftlichen Beweise für die Wirksamkeit
der Therapie vor.
Im
Gegensatz zu den aggressiv vorgetragenen Werbeaussagen
der Produzenten von Testosteron-Präparaten
konnten die unabhängigen Wissenschaftler bei
ansonsten gesunden Männern im fortgeschrittenen
Lebensalter keinerlei Hinweise auf eine Wirkung
der Therapie mit Testosteron finden. Damit wird
die These bestätigt, dass Testosteron nur bei
jenen Männern Anwendung finden sollte, deren
Testosteronproduktion, z.B. aufgrund der operativen
Entfernung der Hoden, völlig versiegt ist.
Im Gegensatz zu den Frauen nimmt die Hormonproduktion
im Alter bei den meisten Männern nicht nahezu
automatisch ab. Wenn aber kein deutlicher Hormonmangel
vorliegt, kann die Zufuhr von zusätzlichen
Sexualhormonen keine positive Wirkung entfalten.
Zumindest beim Sexualhormon Testosteron gilt der
Spruch "Viel hilft auch viel!" offenbar
nicht.
Testosterone
Derided As a Health Supplement - Report Discourages
Widespread Use
There
is no evidence that the testosterone being used
by a growing number of American men to boost their
strength, mood or virility is doing them any good
despite the claims being made for the hormone, an
expert panel of doctors concluded recently.
In
a major report from the congressionally chartered
Institute of Medicine (IOM), the panel said testosterone
is "inappropriate for wide-scale use to prevent
possible future disease or to enhance strength or
mood in otherwise healthy older men." The Food
and Drug Administration has approved its use only
for men with a particular medical condition, but
many more have sought it.
Testosterone
was prescribed for more than 800,000 men last year,
the panel found, including many who believe it can
help them build muscle, sharpen their thinking,
increase their libido and slow aging. But the IOM
panel concluded that there is insufficient research
to document these benefits in otherwise healthy
men, or to gauge the magnitude of known increased
risks of prostate cancer and blood clotting.
"For
men whose testosterone is already in the normal
range, there is no proof that it makes them better
in any way," said panel member Deborah Grady
of the University of California at San Francisco.
"If there is no proven benefit for them, they
shouldn't be taking testosterone no matter what
the risk."
Although
women undergo a sudden decline in the female sex
hormone estrogen during menopause, most men experience
a gradual tapering off in testosterone production
that begins in their forties and continues at about
1 percent a year. That decline, sometimes referred
to as "andropause," is the subject of
medical debate, with some researchers saying it
is predictable and normal and others saying it is
associated with diseases and conditions that can
be kept at bay by taking additional testosterone.
The
FDA has approved testosterone only for hypogonadism,
a steep decline in hormone production triggered
by surgery or disease that harms the testes or pituitary
gland. But the IOM panel concluded that a significant
majority of the more than 1.75 million testosterone
prescriptions in 2002 were for men who did not have
the condition. Once the FDA has approved a drug
for one condition, doctors can legally prescribe
it for any medical purpose. Such "off-label"
uses are widespread -- and sometimes controversial.
The
sharp increase in testosterone use since 1999 coincided
with the FDA's approval of new and easier ways to
administer the drug. Testosterone used to be given
only by monthly injections, but men can now get
it as a patch or a gel. Because of the way testosterone
acts in the body, it is not given in pill form in
the United States.
The
panel, which the National Institute on Aging and
the National Cancer Institute asked to review the
issue, called for a series of small studies to determine
whether the hormone can help men cope with some
of the predictable effects of aging. It said the
studies, which have been on hold while the IOM studied
the issue, should not include younger men because
they were expected to receive less benefit for the
same risks.
At
several points in its report, the panel referred
to the dramatic turnaround among researchers and
doctors regarding the usefulness and safety of estrogen
therapy for post-menopausal women. The hormone had
been widely prescribed to reduce the physical discomforts
that can accompany menopause and to potentially
improve the long-term health of older women until
a major federal study found last year that the risks
of estrogen outweigh the limited benefits. As a
result, usage has plummeted.
But
even as the medical consensus on estrogen was changing
sharply, men were increasingly asking doctors for
testosterone. The IOM study reported that the number
of men taking it more than doubled between 1999
and 2002, and the number of prescriptions almost
tripled. Panel Chairman Dan G. Blazer of Duke University
Medical Center said the number of men taking the
drug has continued to increase sharply, with more
than 2 million prescriptions expected this year.
Some
of the increase has been driven by aggressive advertising,
much of which holds out the hope of the very benefits
that the report said have never been confirmed by
rigorous clinical trials. On the Web site for the
market leader AndroGel, for instance, manufacturer
Solvay Pharmaceuticals asks: "Fatigued? Depressed
mood? Low sex drive? Could be your testosterone
is running on empty."
Gabrielle
Braswell, spokeswoman for Solvay, said the company
is pleased by the IOM recommendation for more study
and did not quarrel with the panel's concerns about
broad testosterone use. "We believe it is appropriate
to use [AndroGel] for the conditions approved by
the FDA," she said.
Blazer
said that his group was not urging doctors to stop
prescribing testosterone off-label for otherwise
healthy men, but that physicians and their patients
need to "be thinking more carefully about its
use."
William
Hazzard, a professor at the University of Washington
School of Medicine, said the testosterone issue
is becoming increasingly important with the aging
of the baby-boom generation. "We're concerned
that a population-based drive to increase testosterone
use could be trumping science at this instance,"
he said.
In
a statement, the National Institute on Aging said
it would consider conducting new studies. The statement
added that "although some older men who have
tried these treatments report feeling 'more energetic'
or 'younger,' testosterone therapy remains a scientifically
unproven method for preventing or relieving any
physical or psychological changes that men with
normal testosterone levels may experience as they
get older."
Some
doctors, however, said the report seems to miss
the fact that testosterone has been beneficial to
many men. "There is a disconnect between some
of the conclusions and recommendations that come
out of this, and what I and other doctors see in
clinical practice," said Abraham Morgentaler,
a professor at Harvard Medical School.
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