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Selected Scientific Advances in
Preventing and Treating Osteoporosis
Identification of a gene essential
for the formation of bone. Through a
convergence of efforts by
investigators around the world,
research has shown that normal
skeletal development--in both mice
and humans--requires two active
copies of the gene Cbfa1. This
discovery is expected to open a
number of exciting new research
areas.
Finding that estrogen causes
"programmed cell death" in cells
that are responsible for degradation
of bone (osteoclasts). By paving the
way for future assessment of whether
drugs can also affect the programmed
cell death of osteoclasts (thereby
making them potentially useful as
bone-protecting treatments), this
discovery represents an exciting
link between basic research and
tangible patient benefit.
Finding that one of a collection of
molecules created by researchers
(called peptidomimetics)
successfully blocks part of the bone
resorption process. This is the
first clear indication that a
particular synthetic antagonist may
be effective in the prevention of
osteoporosis. The finding may hold
promise for combating bone loss in
women who cannot tolerate estrogen.
Patient-based research showing that
elderly women who already had
several spine fractures at the start
of a study experienced the greatest
health benefit from calcium
supplementation (both in terms of
reducing the rate of new spine
fractures and stopping bone loss).
This finding has clear implications
for developing and targeting new
preventive strategies.
Low-dose estrogen study. A recent
study supported by NIAMS tested the
usefulness of daily low-dose
estrogen plus progesterone in women
over age 65 and found that these
women showed significant increases
in spine, forearm, and total body
bone mineral density. This study
provides proof that low-dose
estrogen can be an effective
preventive and therapeutic option.
Study of osteoporotic fractures (SOF).
The development of risk-prediction
models for osteoporotic fractures
that incorporate clinical risk
factors along with bone mineral
density measurements is an important
advance in identifying persons at
greatest risk for fractures and for
whom intervention measures may be
suitable. The SOF, a study of
postmenopausal Caucasian women, led
to the identification of 14 clinical
risk factors. Possession of five or
more of these factors greatly
increased the risk of fracture in
the women in the study.
Secondary osteoporosis. Information
regarding the diseases, physical
states, medical treatments, and
drugs that can lead to the
development of secondary
osteoporosis is now available to
physicians. The information alerts
physicians to the appropriate use of
treatment, the monitoring of
patients at risk, and, where
possible, the use of intervention
measures to prevent the development
of osteoporosis. For example, it is
generally agreed that patients on
glucocorticoid therapy for 2 months
or longer and patients whose
conditions place them at high risk
for osteoporotic fractures should be
considered for bone density
measurement.
Screening in the general population.
Because there is a lack of
sufficient evidence regarding the
cost-effectiveness of routine
screening or the efficacy of early
initiation of preventive drugs, an
individualized approach is
recommended for testing for bone
loss.
Testosterone study. Circulating
levels of testosterone are known to
decline in men as they age, leading
to bone loss. A recent clinical
trial of testosterone
supplementation in a group of older
men with low hormone levels revealed
little difference in bone mineral
density between the placebo- and
testosterone-treated men, indicating
that hormone therapy to replace bone
mass is not necessary for most older
men.
Gene for osteoporotic fractures. A
recent study showed that women 65
and older with the apolipoprotein E
(APOE*4) gene on chromosome 19 were
nearly twice as likely as those
without the gene to suffer hip and
wrist fractures. Women with this
gene experience weight loss that
contributes to bone loss and may
have reduced levels of vitamin K,
which stimulates bone formation and
reduces bone-cell loss.
Body mass index. Suboptimal bone
growth in childhood and adolescence
is as important as bone loss to the
development of osteoporosis. Growth
hormone and insulin-like growth
factor-I, which are secreted the
most during puberty, play a role in
acquiring and maintaining bone mass
and in determining body composition
into adulthood. Children and youth
with low body mass index (BMI) are
likely to have a lower-than-average
peak bone mass. There is a direct
association between BMI and bone
mass throughout the adult years, and
several studies of fractures in
older persons have shown an inverse
relationship between fracture rates
and BMI.
Nutritional studies. It is known
that calcium is essential for
building strong bones and reducing
fracture risk. Vitamin D is required
for optimal calcium absorption by
the body. Both substances should be
part of any osteoporosis treatment.
Recent studies have shown that while
some substances, such as high
dietary protein, caffeine,
phosphorus, and sodium, can
adversely affect calcium balance,
their effects appear not to be
important in individuals who have an
adequate calcium intake.
Gender/ethnicity. Caucasian
postmenopausal women experience
almost three-quarters of hip
fractures. However, women of other
age, racial, and ethnic groups, as
well as men and children, are also
affected by osteoporosis. Much of
the difference in fracture rates
among these groups appears to be
explained by differences in peak
bone mass and rate of bone loss.
Differences in bone geometry,
frequency of falls, and presence of
other risk factors also appear to
play a role.
New drugs. Bisphosphonates and
selective estrogen receptor
modulators (SERMs) are fairly recent
prevention and treatment options for
osteoporosis. Randomized
placebo-controlled trials and
meta-analysis of bisphosphonates (etidronate,
alendronate, and risedronate) show
that all increase bone mineral
density at the spine and hip in a
dose-dependent manner and reduce the
risk of vertebral fractures by 30 to
50 percent. In large clinical
trials, raloxifene, a SERM recently
approved by the Food and Drug
Administration, reduced the risk of
vertebral fracture by 36 percent.
Exercise and falls. There is some
evidence that childhood exercise,
particularly resistance and
high-impact exercise (such as weight
training), contributes to higher
peak bone mass. While there are
health benefits to low-impact
exercise, such as walking, it has
minimal benefit for bone mineral
density. Acknowledging that falls
are a major risk factor for
osteoporotic fractures, researchers
conducted randomized clinical
studies of exercise during adulthood
and later in life that showed that
the conditioning, balance-enhancing,
and muscle-building effects of
exercise reduce falls by
approximately 25 percent.
Ultrasound. Clinical trials of drug
therapy for osteoporosis have most
often used dual energy x-ray
absorptiometry (DXA) to measure bone
mineral density. Studies of the less
cumbersome and less expensive
quantitative ultrasound (QUS) of the
heel show that QUS predicts hip
fracture and other nonvertebral
fractures nearly as well as DXA at
the femoral neck.
Biomarkers. Biomarkers of bone
remodeling (formation and
breakdown), such as alkaline
phosphatase and osteocalcin (serum
markers) and pyridinolines and
deoxypyridinolines (urinary
markers), are of limited utility in
evaluating individual patients
because they do not predict bone
mass or fracture risk. However,
research studies show that
biomarkers correlate with changes in
indices of bone remodeling and may
provide insights into the mechanisms
of bone loss
Content Courtesy : www.niams.nih.gov
Note : Information herein is
provided for informational purposes
only and is not a substitute for
professional medical advice. You
should not use this information for
diagnosing or treating a medical or
health condition. If you have or
suspect you have a medical problem,
promptly contact your professional
healthcare provider. Please consult
your healthcare provider before
beginning any course of
supplementation or treatment.
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