porosis
- an overview.
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by The Osteoporosis and Related Bone Diseases
National Resource Center (USA
Osteoporosis, or porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue. leading to bone fragility and an increased susceptibility to fractures of the hip, spine and wrist. Men as well as women suffer from osteoporosis, a disease that can he prevented and treated.
What is Bone?
Bone is living, growing tissue. It is made mostly of collagen, a protein
that provides a soft framework, and calcium phosphate, a mineral that adds
strength and hardens the framework. This combination of collagen and
calcium makes bone strong yet flexible to withstand stress. More than 99%
of the body’s calcium is contained in the bones and teeth. The remaining
1% is found in the blood.
Throughout
your lifetime, old bone is removed (resorption) and new bone is added to
rhe skeleton (formation). During childhood and teenage years, new bone is
added faster than old bone is restored. As a result, bones become larger,
heavier and denser. Bone formation continues at a pace faster than
resorption until peak bone mass (maximum bone density and strength) is
reached during the mid-20s. After age 30, bone resorption slowly begins to
exceed bone formation. Bone loss is most rapid in the first few years
after menopause but persists into the postmenopausal years. Osteoporosis
develops when bone resorption occurs too quickly or if replacement occurs
too slowly. Osteoporosis is more likely to develop if you did not reach
optimal bone mass during your bone building years.
Risk Factors
Certain factors are linked to the development of osteoporosis or
contribute to an individual’s likelihood of developing the disease.
These are called “risk factors.” Many people with osteoporosis have
several of these risk factors, but others who develop osteoporosis have no
identified risk factors. There are some risk factors that you cannot
change, and others that you can.
Risk factors you cannot change
-
Gender – Your chances of developing osteoporosis are greater if you are a woman. Women have less bone tissue and lose bone more rapidly than men because of the changes involved in menopause.
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Age – The older you are, the greater your risk of osteoporosis. Your bones become less dense and weaker as you age.
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Body size – Small, thin-boned women are at greater risk.
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Ethnicity – Caucasian and Asian women are at highest risk. African-American and Hispanic women have a lower but significant risk.
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Family history – Susceptibility to fracture may he, in part, hereditary. People whose parents have a history of fractures also seem to have reduced bone mass and may be at risk for fractures.
Risk factors you can change:
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Sex hormones: abnormal absence of menstrual periods (amenorrhea), low estrogen level (menopause), and low testosterone level in men.
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Anorexia.
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A lifetime diet low in calcium and vitamin D.
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Use of certain medications, such as glucocorticoids' or some anticonvulsants.
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An inactive lifestyle or extended bed rest.
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Cigarette smoking.
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Excessive use of alcohol.
Prevention
To reach optimal peak bone mass and continue building new bone tissue as
you get older, there are several factors you should consider:
Calcium
–
An inadequate supply of calcium over the lifetime is thought to play a
significant role in contributing to the development of osteoporosis. Many
published studies show that low calcium intakes appear to be associated
with low bone mass, rapid bone loss, and high fracture rates. National
nutrition surveys have shown that many people consume less than half the
amount of calcium recommended to build and maintain healthy bones. Good
sources of calcium include low fat dairy products, such as milk, yoghurt,
cheese and ice cream; dark green, leafy vegetables, such as broccoli,
collard greens, bok choy and spinach; sardines and salmon with bones;
tofu; almonds; and foods fortified with calcium, such as orange juice,
cereals and breads. Depending upon how much calcium you get each day from
food, you may need to take a calcium supplement.
Calcium needs change during one's lifetime. The body’s demand for
calcium is greater during childhood and adolescence when the skeleton is
growing rapidly, and during pregnancy and breast feeding. Postmenopausal
women and older men also need to consume more calcium. This may be caused
by inadequate amounts of Vitamin D, which is necessary for intestinal
absorption of calcium. Also, as you age, your body becomes less efficient
at absorbing calcium and other nutrients. Older adults also are more
likely to have chronic medical problems and to use medications that may
impair calcium absorption.
Vitamin D. Vitamin D plays an important role in calcium absorption and in bone health. It is synthesized in the skin through exposure to sunlight. While many people are able to obtain enough Vitamin D naturally, studies show that Vitamin D production decreased in the elderly, in people who are house-bound, and during the winter. These individuals may require Vitamin D supplementation to insure a daily intake of between 400 to 8OO IU of Vitamin D. Massive doses are not recommended.
Exercise.
Like muscle, bone is living tissue that responds to exercise by becoming
stronger. The best exercise for your bones is weight-bearing exercise,
that forces you to work against gravity. These exercises include walking,
hiking, jogging, stair-climbing, weight training, tennis and dancing.
Smoking.
Smoking is bad for your bones as well as for your heart and lungs. Women
who smoke have lower levels of estrogen
compared to non-smokers and frequently go through menopause
earlier. Postmenopausal women who smoke may require higher doses of
hormone replacement therapy and may have more side effects. Smokers also
may absorb less calcium from their diets.
Alcohol.
Regular
consumption of 2 to 3 ounces a day of alcohol may be damaging to the
skeleton, even in young women and men. Those who drink heavily are more
prone to bone loss and fractures, both because of poor nutrition as well
as increased risk of falling.
Medications that cause bone loss. The long-term use of glucocorticoids (medications prescribed for a wide range of diseases, including Addison’s, arthritis, asthma, Crohn’s, lupus and other diseases of the lungs, kidneys and liver) can lead to a loss of bone density and fractures’. Other forms of drug therapy that can cause bone loss include long-term treatment with certain anti-seizure drugs, such as phenytoin (Dilantin), barbiturates, and valproate (Depakote); gonadotropin releasing hormone (GnRH) analogs used to treat endometriosis; excessive use of aluminium-containing antacids; certain cancer treatments; and excessive thyroid hormone; It is important to discuss the use of these drugs with your physician, and not to stop or alter your medication dose on your own.
Symptoms
Osteoporosis is often called the "silent disease” because bone loss
occurs without symptoms. People may not know that they have osteoporosis
until their bones become so weak that a sudden strain, bump, or fall
causes a hip fracture or a vertebra to collapse. Collapsed vertebrae may
initially be felt or seen in the form of severe back pain, loss of height,
or spinal deformities such as kyphosis, or severely stooped posture.
Detection
Following a comprehensive medical assessment, your doctor may recommend
that you have your bone mass measured. Bone mineral density (BMD) tests
measure bone density in the spine, wrist, and/or hip (the most common
sites of fractures due to osteoporosis), while others measure bone in the
heel or hand. These tests are painless, non-invasive, and safe. Bone
density tests can:
- Detect
low bone density before a fracture occurs.
- Confirm
a diagnosis of osteoporosis if you have already fractured,
- Predict
your chances of fracturing in the future.
- Determine
your rate of bone loss and/or monitor the effects of treatment if the
test is conducted at intervals of a year or more.
To find the location of a bone density testing centre near you, call the National Osteoporosis Foundation at 1-800-464-6700 (In the USA only).
Treatment
A comprehensive osteoporosis treatment program includes a focus on proper
nutrition, exercise, and safety issues to prevent falls that may result in
fractures. In addition, your physician may prescribe a medication to slow
or stop bone loss, increase bone density, and reduce fracture risk.
- Nutrition: The foods we eat contain a variety of vitamins, minerals, and other important nutrients that help keep our bodies healthy. All of these nutrients are needed in a balanced proportion. In particular, calcium and vitamin D are needed for strong bones as well as for your heart, muscles, and nerves to function properly.
- Exercise: Exercise is an important component of an osteoporosis prevention and treatment program. Exercise not only improves your bone health, but it increases muscle strength, coordination, and balance and leads to better overall health. While exercise is good for someone with osteoporosis, it should not put any sudden or excessive strain on your bones. As extra insurance against fractures, your doctor can recommend specific exercises to strengthen your back.
Therapeutic
Medications:
Currently, estrogen , calcitonin, and alendronate are approved by the U.
S. Food and Drug Administration (FDA) for the treatment of post-menopausal
osteoporosis. Estrogen, raloxifene and alendronate are approved for the
prevention of the disease.
- Estrogen - Estrogen replacement
therapy (ERT) has been shown to reduce bone loss, increase bone
density in both the spine and hip, and reduce the risk of hip and
spinal fractures in postmenopausal women. ERT is administered most
commonly in the form of a pill or skin patch and is effective even
when started after age 70. When estrogen
is taken alone, it can increase a woman’s risk of developing
cancer of the uterine lining (endometrial cancer). 1'o eliminate this
risk, physicians prescribe the hormone progestin in combination with
estrogen (hormone replacement therapy or HRT) for those women who have
not had a hysterectomy ERT/HRT relieves menopause symptoms and has
been shown to have beneficial effects on both the skeleton and heart.
Experts recommend ERT for women at high risk for osteoporosis. ERT is approved for both the prevention and treatment of osteoporosis. ERT is especially recommended for women whose ovaries were removed before age 50. Estrogen replacement should also be considered by women who have experienced natural menopause and have multiple osteoporosis risk factors, such as early menopause, family history of osteoporosis,. or below-nor-mal bone mass for their age. As with all drugs, the decision to use estrogen should be made after discussing the benefits and risks and your own situation with your doctor. - Raloxifene – Raloxifene (brand name Evista) is a drug that was recently approved for the prevention of osteoporosis. It is from a new class of drugs called Selective Estrogen Receptor Modulators (SERMs) that appear to prevent bone loss at the spine, hip and total body. Raloxifene’s effect on the spine does not appear to be as powerful as either estrogen replacement therapy or alendronate, but its effect on the hip and total body are more comparable. While side effects are not common with Raloxifene, those reported include hot flashes and deep vein thrombosis, the latter of which is also associated with estrogen therapy. Additional research studies on Raloxifene will be ongoing for several more years.
- Alendronate – Alendronate (brand name Fosamax) is a medication from the class of drugs called bisphosphonates. Like estrogen, alendronate is approved for both the prevention and treatment of osteoporosis. In post-menopausal women with osteoporosis, the bisphosphonate alnidronate reduces bone loss, increases bone density in both the spine and hip, and reduces the risk of both spine fractures and hip fractures. Side effects from alendronate are uncommon, but may include abdominal or musculoskeletal pain, nausea, heartburn, or irritation of the oesophagus. The medication should be taken on an empty stomach and with a full glass of water first thing in the morning. After taking alendronate, it is important to wait in an upright position for at least one half hour, or preferably one hour, before the first food, beverage, or medication of the day.
- Calcitonin
– Calcitonin is a naturally occurring non-sex hormone involved in
calcium regulation and bone metabolism. In women who are at least five
years beyond menopause, calcitonin slows bone loss, increases spinal
bone density and, according to anecdotal reports, relieves the pain
associated with bone fractures. Calcitonin reduces the risk of spinal
fractures and may reduce hip fracture risk as well. Studies on
fracture reduction are ongoing. Calcitonin is currently available as
an injection or nasal spray. While it does not affect other organs or
systems in the body, injectable calcitonin may cause an allergic
reaction and unpleasant side effects including flushing of the face
and hands, urinary frequency, nausea, and skin rash. The only side
effect reported with nasal calcitonin is a runny nose.
Fall
Prevention
Fall prevention is a special concern for men and women with osteoporosis.
Falls can increase the likelihood
of
fracturing a bone in the hip, wrist, spine or other part of the skeleton.
In addition to the environmental factors list-ed below, falls can also be
caused by impaired vision and/or balance, chronic diseases that impair
mental or physical functioning, and certain medications, such as sedatives
and antidepressants. It is important that individuals with osteoporosis be
aware of any physical changes they may be experiencing that affect their
balance or gait, and that they discuss these changes with their health
care provider.
Some tips to help eliminate the environmental factors that lead to falls include:
- Outdoors
– Use a cane or walker for added stability; wear rubber-soled shoes
for traction; walk on grass when sidewalks are slippery; in winter,
carry salt or kitty litter to sprinkle on slippery sidewalks; be
careful on highly polished floors that become slick and dangerous when
wet. Use plastic or carpet runners when possible.
- Indoors
– Keep rooms free of clutter, especially floors; keep floor surfaces
smooth but not slippery; wear supportive, low-healed shoes even at
home; avoid walking in socks, stockings, or slippers; be sure carpets
and area rugs have skid-proof backing or are tacked to the floor; be
sure stairwells are well lit and that stairs have handrails on both
sides; install grab bars on bathroom walls near tub, shower, and
toilet; use a rubber bath mat in shower or tub; keep a flashlight with
fresh batteries beside your bed; if using a step-stool for
hard-to-reach areas, use a sturdy one with a handrail and wide steps;
add ceiling fixtures to rooms lit by lamps. Consider purchasing a
cordless phone so that you don’t have to rush to answer the phone
when it rings or you can call for help if you do fall.
Addison’s Disease sufferers who rely on glucocorticoids as replacement therapy must bear in mind that their levels of replacement hormone are minimal, mimicking the missing but natural levels of steroids, and should not cause significant increases in bone loss. Since cortisone replacement in Addison’s disease is prescribed to simulate the body’s normal physiologic production, it is unlikely that the person who is being closely monitored would he exposed to excessive doses, which can cause osteoporosis. But some Addisonians have experienced osteoporosis. Therefore, calcium supplements and periodic bone density testing may be considered as a hedge against bone loss from a variety of factors. The National Osteoporosis Foundation (NOF) welcomes calls to locate a bone-density testing location in your area (USA only). They also offer educational pamphlets on products or programs for people with osteoporosis.
This article first published in NADF News Sprint & Summer 1998
The
Osteoporosis and Related Bone Diseases National Resource Center seeks to
create an awareness of osteoporosis, Paget's disease and osteogenesis
imperfecta, and of the general possibilities for therapy. Remedial
action in each individual case should be determined with professional
medical advice directed toward the individual's particular circumstances
and condition.
