General Description
Osteoporosis is a skeletal disorder characterized by compromised
bone strength and an increased risk of fractures, especially of
the hip, spine, and wrist. It is estimated that 10 million people
in the U.S. have osteoporosis and an additional 18 million have
low bone mass, placing them at increased risk for the disease.1
Although it is the underlying cause of most fractures in older people,
in most cases osteoporosis remains undetected until a fracture occurs.
In the U.S., osteoporosis is responsible for more than 1.5 million
fractures annually, including approximately 300,000 hip fractures,
700,000 vertebral fractures, 250,000 wrist fractures, and more than
300,000 fractures at other sites.1 While the
disease is most commonly seen in post-menopausal white and Asian
women, osteoporosis occurs in all ethnic and gender groups. Once
considered to be a natural part of aging, osteoporosis is now recognized
as a largely preventable disease.
Contributing factors
Bone strength is a reflection of two main features: bone density
and bone quality. Bone density is expressed as grams of mineral
per volume and is determined by peak bone mass and amount of bone
loss. Bone quality refers to architecture, turnover, damage accumulation
(e.g., microfractures) and mineralization. Currently there is
no accurate measure of overall bone strength. Bone mineral density
(BMD), which accounts for approximately 70 percent of bone strength,
is frequently used as a proxy measure. Osteoporosis is diagnosed
when BMD measurements are markedly below the average for healthy
young adults. This often results from accelerated bone loss associated
with aging, but may also occur without accelerated bone loss in
individuals who do not achieve optimal bone mass during childhood
and adolescence. Thus, sub-optimal bone growth in childhood is
as important as bone loss to the development of osteoporosis.2
Optimization of bone health is a process that must occur throughout
one's lifetime. Factors that influence bone health at all ages
are essential to the prevention of osteoporosis.
Osteoporosis is characterized as primary or secondary. Primary
osteoporosis can occur in both genders at all ages, but is most
often seen in post-menopausal women and elderly men. Secondary
osteoporosis is caused by medication side effects or other diseases
or conditions such as alcoholism, genetic disorders, gastrointestinal
diseases, endocrine disorders, connective tissue diseases, hypogonadism,
and nutritional deficiencies.2 These secondary
causes can aggravate primary osteoporosis.
The development of primary osteoporosis is often associated
with aging, largely because of the role hormones play in bone
preservation. The female hormone estrogen helps protect bones
against mineral loss. After menopause, women's estrogen levels
decline drastically, which can lead to bone loss and osteoporosis.
Men have less risk of developing osteoporosis because they do
not experience the same kinds of hormone losses as women. Because
of this, osteoporosis does not normally affect men until they
reach advanced age.
Conventional treatment
Treatment of osteoporosis aims to stop bone loss and prevent falls.
Falls often cause the bone fractures that typify osteoporosis.
Many doctors prescribe hormone replacement therapy (HRT) to restore
declining hormone levels and slow the rate of bone loss. However,
the long-term safety of HRT is not yet known. The naturally occurring
hormone calcitonin can increase bone density in the spine and
reduce the pain of fractures.3 The prescription
drug alendronate (Fosamax¬) helps maintain bone mass in postmenopausal
women by inhibiting the activity of cells that draw calcium out
of bone tissues.4,5
Nutritional/lifestyle considerations
Osteoporosis is viewed as a preventable disease, with diet and
exercise as the primary interventions. Because bones are composed
mostly of calcium, a calcium-rich diet, or supplemental calcium,
is important for all people at risk for osteoporosis. These people
should also be sure they have adequate vitamin D, a nutrient the
body needs in order to absorb calcium. Because peak bone density
is established during childhood and adolescence, intake of calcium
and vitamin D during these years is important for reducing the
risk of osteoporosis later in life. Several other minerals such
as magnesium, zinc, copper, boron, and silica along with vitamin
K, also contribute to bone formation. A combination of healthy
diet and exercise is the best way to prevent osteoporosis. Exercise
builds bone strength and helps prevent bone loss. Weight-bearing
exercises such as walking, jogging, or playing tennis, done on
a regular basis, are best for preventing osteoporosis.3
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