osteoporosis

Osteoporosis Ways to prevent brittle bones.

More about Osteoporosis: Causes and symptoms Diagnosis Treatment Alternative treatment Prognosis Prevention Resources

Definition

The word osteoporosis literally means "porous bones." It occurs when bones lose an excessive amount of their protein and mineral content, particularly calcium. Over time, bone mass, and therefore bone strength, is decreased. As a result, bones become fragile and break easily. Even a sneeze or a sudden movement may be enough to break a bone in someone with severe osteoporosis.

Description

Osteoporosis is a serious public health problem. Some 28 million people in the United States are affected by this potentially debilitating disease, which is responsible for 1.5 million fractures (broken bones) annually. These fractures, which are often the first sign of the disease, can affect any bone, but the most common locations are the hip, spine, and wrist. Breaks in the hip and spine are of special concern because they almost always require hospitalization and major surgery, and may lead to other serious consequences, including permanent disability and even death.

To understand osteoporosis, it is helpful to understand the basics of bone formation. Bone is living tissue that's constantly being renewed in a two-stage process (resorption and formation) that occurs throughout life. In the resorption stage, old bone is broken down and removed by cells called osteoclasts. In the formation stage, cells called osteoblasts build new bone to replace the old. During childhood and early adulthood, more bone is produced than removed, reaching its maximum mass and strength by the mid-30s. After that, bone is lost at a faster pace than it's formed, so the amount of bone in the skeleton begins to slowly decline. Most cases of osteoporosis occur as an acceleration of this normal aging process. That's referred to as primary osteoporosis. The condition can also be caused by other disease processes or prolonged use of certain medications that result in bone loss—if so, it's called secondary osteoporosis.

Osteoporosis occurs most often in older people and in women after menopause. It affects nearly half of all those, men and women, over the age of 75. Women, however, are five times more likely than men to develop the disease. They have smaller, thinner bones than men to begin with, and they lose bone mass more rapidly after menopause (usually around age 50), when they stop producing a bone-protecting hormone called estrogen. In the five to seven years following menopause, women can lose about 20% of their bone mass. By age 65 or 70, though, men and women lose bone mass at the same rate. As an increasing number of men reach an older age, there's more awareness that osteoporosis is an important health issue for them as well.

— Barbara Boughton

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n., pl. -ses (-sēz).

A disease in which the bones become extremely porous, are subject to fracture, and heal slowly, occurring especially in women following menopause and often leading to curvature of the spine from vertebral collapse.

[New Latin : OSTEO– + Greek poros, passage, pore; see pore² + –OSIS.]

osteoporotic os'te·o·po·rot'ic (-rŏt'ĭk) adj.

A metabolic bone disease in which the amount of bone tissue is reduced sufficiently to increase the likelihood of fracture. Fractures of the vertebrae, femur (hip), and wrist are the most common osteoporotic fractures, but other bones such as the ribs, upper arm, and pelvis may also fracture.

Although low bone mass is the major factor in osteoporotic fractures, there may also be qualitative and architectural changes in bone with aging that lead to increased fragility. Osteoporosis can be primary or secondary. Primary osteoporosis occurs independently of other causes. The secondary osteoporoses result from identifiable causes, such as exogenous cortisone administration, Cushing's disease, hyperparathyroidism, hyperthyroidism, hypogonadism, multiple myeloma, prolonged immobilization, alcoholism, anorexia nervosa, and various gastrointestinal disorders. Primary osteoporosis occurring in children is called juvenile osteoporosis; that occurring in premenopausal women and middle-aged or young men is known as idiopathic osteoporosis. Osteoporosis, which is found in older persons, can be classified as postmenopausal (type I) or involutional (type II) osteoporosis. See also Alcoholism; Anorexia nervosa; Gastrointestinal tract disorders; Metabolic disorders.

Goals should include prevention of both the underlying disorder (the disease) and its effects (osteoporotic fractures). Secondary osteoporoses are managed by eliminating the underlying disorder. To prevent primary osteoporosis, good health-related behavior during childhood and young adulthood has been suggested as the most important factor. Such behavior includes avoiding cigarette smoking and excess alcohol intake, maintaining a normal body weight, and maintaining optimal dietary intake of calcium. It has been suggested that the recommended daily allowance (RDA) for calcium in the postmenopausal period and the recommended intake of vitamin D in the aged should be increased. At menopause, the possibility of estrogen replacement therapy should be considered for women who are at high risk for osteoporosis. Fracture prevention should be a lifelong effort. During childhood and the premenopausal years, a maximal peak bone mass should be developed through weight-bearing exercise. Exercise to improve coordination and flexibility and to maintain good posture is also useful. See also Estrogen; Nutrition; Vitamin D.

The diagnosis of primary osteoporosis is made in the presence of either low bone mass or a characteristic fracture that cannot be attributed to some other cause.

The goals of treatment are rehabilitation and minimization of the risk of future fractures. Goals for rehabilitation include restoring a positive outlook on life, treating depression if it exists, increase of physical activity, restoring independence, relieving pain, restoring muscle mass, and improving posture. Various medications, including estrogen and calcitonin, can maintain bone mass. See also Aging; Bone; Skeletal system disorders.

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Osteoporosis is a condition in which the bones become porous and weak, and therefore fracture easily. The bone tissue is normal with a normal shape but it has lost mass and density and so lacks sufficient strength to withstand the forces which normally occur in daily life. There are no symptoms initially and the condition is often diagnosed only when a bone fracture occurs unexpectedly. These fractures occur in a third of all women and in one in twelve men. Post-menopausal and senile osteoporosis are recognized. The former is due to loss of oestrogen, the latter includes a time-dependent loss of bone common to men and women. Osteoporosis also occurs as a side-effect of some drug treatments, with oral corticosteroids for example, and occasionally, in a severe and little understood form at much younger ages.

Osteoporosis is often confused with osteoarthritis, another chronic problem of later life. However, osteoarthritis is a disease of the joints which is rare in those who have osteoporosis (unless they have been treated with corticosteroids).

Osteoporosis is not a disease like those caused by viral or bacterial infection, but a long term consequence of a small imbalance in the natural process of bone remodelling. Bone is a living tissue which constantly remodels itself through a process of resorption and formation known as bone turnover. Most processes in the body slow down as we grow older but bone turnover speeds up and the balance tips in favour of resorption, resulting in net bone loss. A greater imbalance develops in some people than in others and they are the ones who will suffer from osteoporosis, especially if they began with relatively low bone mass in middle age. This variation is to a large extent genetically determined, but lifestyle factors also contribute, including smoking, lack of exercise, low dietary calcium intake and, in the elderly, lack of vitamin D. Individuals who are small and thin are at greater risk because of their low bone mass compared with heavier individuals. Women who had an early menopause, or whose menstrual periods failed when they were young perhaps due to anorexia, are also at increased risk because the skeleton has had more prolonged exposure to a low oestrogen level. Although the process of resorption and formation is at the root of the osteoporotic condition, it is nevertheless a useful process which ensures that bone can repair minor damage and remodel itself in response to changing mechanical loads. It means that bone can respond positively to exercise and to drug treatments. Most of the effective drugs, such as bisphosphonates and hormone replacement therapy (HRT), act by slowing down resorption and therefore slowing the rate of loss of bone or tipping the balance in favour of formation.

The sites most commonly affected by osteoporosis are the wrist, the vertebrae in the spine, and the top of the femur (the hip). Vertebral fractures lead to collapse of the vertebrae which results in substantial loss of height or marked curvature of the spine (the Dowager's hump) and sometimes severe pain. Hip fractures occurring in the elderly in Britain cost the NHS nearly £1 billion in 1997 and the fracture rate has been rising faster than the increase in the number of elderly people in the population. The mortality rate following hip fracture is high and survivors usually suffer loss of independence and mobility. Both of these manifestations of osteoporosis were considered to be part of the normal ageing process until the middle of the twentieth century, and it was not until 1986 that the National Osteoporosis Society was established to provide support for sufferers, and advice and reliable information about the disease, which are still not widely available.

The osteoporotic condition develops slowly until so much bone has been lost that a threshold of vulnerability is reached and irreversible damage is likely. Preventative strategies are needed before this fragile state is reached. HRT is particularly useful for preventing post-menopausal loss in potentially vulnerable women. Adequate dietary calcium is essential. Dairy products such as cheese, yoghurt, and milk are rich in calcium. A pint of skimmed milk contains 700 mg which is the daily intake recommended in Britain. Smoking should be avoided, including passive smoking: it is known to interfere with the effect of oestrogen on bone. Excessive amounts of alcohol or caffeine (in tea, coffee, and coke) are also associated with a higher risk of osteoporosis.

The natural stimulus for bone to maintain its functional strength is the loading which results from gravitational forces and the tensions exerted by muscular activity. Astronauts lose bone while floating in space and so do patients who are confined to bed for long periods. Conversely, physically active people have higher bone mineral density compared with those who are sedentary. Exercise therefore has a role in reducing the long-term risk of osteoporotic fracture. The most effective exercise provides a regular series of varied short sharp loads to the sites which are most vulnerable for fracture. Brief exposure such as running up and down stairs a few times each day may be enough. Intermittent jogging (‘scouts' pace’) is useful, and so is weight-training, provided that over 70% of personal maximum effort is used in lifting slowly with a few repetitions. Research is still ongoing to find the best prescriptions. Improvements can probably occur at any age, but the increases appear to be largest before adolescence, and in later life vigorous exercise is obviously only safe for those who still have a robust skeleton. Bone changes slowly, improvements take months, and if the exercise is discontinued they are gradually lost again. In older people moderate exercise may prevent further loss of bone, and since fracture risk is only likely when bone density has fallen below a threshold value, maintenance is useful.

— Joan Bassey

Bibliography

• The National Osteoporosis Society publishes booklets. Helpline 01761 471771

See also bone; hormone replacement therapy; menopause.

Degeneration of the bones with advancing age due to loss of bone mineral and protein as a result of decreased secretion of hormones (oestrogens in women and testosterone in men). A high calcium intake in early life may be beneficial, since this may result in greater bone density at maturity.

brittle bone disease

A group of diseases characterized by a reduction in bone mass due to bone reabsorption outpacing bone deposition. The disease is usually associated with loss of weight. Other symptoms include feelings of lassitude, bone pains, and acute back pain. However, the most harmful effect of the disease is that bone becomes porous, brittle, and inclined to fracture. Over 250 000 Americans, most of them elderly, fall and break their hips each year, resulting in a $10 billion medical bill. Worldwide, the disease affects 1.7 million people each year. The number is expected to grow to over 6 million a year by 2050. A quarter of these people are expected to die within six months because of complications, usually linked to hip fractures.

Osteoporosis is an age-related disease, primarily affecting post-menopausal women, although it can occur much earlier in life (figure 47). There is always some degree of bone weakening with age, but insufficient exercise and a low calcium diet (especially in early life) may exacerbate this. Excessive exercising and weight-loss dieting are also linked with development of the disease. Development of the disease may be determined to some extent by a single gene. A gene affecting Vitamin D metabolism has been found in Australians which may be responsible for more than 75 per cent of the genetic variation in their bone density. If this gene occurs in a broader population, it may not be long before genetic screening can be used to identify those who are predisposed to the disease, so that preventative measures can be taken.

Figure 47 Osteoporosis. Images such as these have been used by the National Osteoporosis Society (UK) to heighten awareness and to encourage women to take preventative measures

Physical exercise reduces the risk of osteoporosis. Moderate weight-bearing exercises, such as leisurely cycling, dancing, walking, and tennis, stimulate the deposition of calcium, strengthen bones, and reduce the risk of osteoporosis. However, young people benefit most from exercise; strong and healthy bones are more easily established in adolescents and young adults. A modest amount of jumping (as little as 50 jumps a day) can increase the density of hips in premenopausal women by as much as 3 per cent. Although exercise may offer some protection against acquiring the disease, those already suffering from osteoporosis should avoid contact sports and exercise that put undue stress on bones and joints. In particular, flexion exercises of the spine (e.g. sit ups) should be avoided because of the risk of vertebral fractures. Swimming is an especially good exercise for those with the disease.

Slightly overweight post-menopausal women are less likely to suffer from brittle bones than slim women. Possible reasons are that fat acts as a protective cushion; bones of plump women may be heavier and stronger; and the extra fat of plumper women enables them to produce more oestrogen which offers some protection against demineralization of bones.

A diet that includes a good intake of calcium-rich food (e.g. milk, yogurt, and cheese) may help prevent and minimize problems associated with this disease. It appears that it is particularly important for pre-menopausal women to have adequate calcium intakes so that they can achieve maximum peak bone densities. At present, the UK Reference Nutrient Intake is thought by The National Osteoporosis Society (UK) to be too low. They recommend the following calcium intakes:

• children 7-12 years	800 mg per day
• teenagers/adults	1000 mg per day
• women over 45 (not on HRT)	1500 mg per day
• women over 45 (on HRT)	1000 mg per day
• pregnant and lactating teenagers	1500 mg per day
• pregnant and lactating adults	1200 mg per day
• men over 45 years	1500 mg per day

Some doctors believe that the best way to prevent osteoporosis in post-menopausal women is hormone replacement therapy (see menopause), but this treatment is not suitable for all women. See also amenorrhoea and parathyroid hormone.

(os′tē ōpôrō′sis)
n

An enlargement of the soft marrow and haversian spaces resulting from a decreased rate of formation of the hard bone matrix. With the exception of immobilized parts, it is a systemic disorder that occurs in advanced age (senile osteoporosis), during ACTH and cortisone therapy, during and after menopause, in limited physical activity, in Cushing’s syndrome, during malnutrition, and in other disorders of matrix formation such as hyperadrenalism, hyperthyroidism, vitamin C deficiencies, and deficiency of androgenic steroids. See also atrophy, bone and bone rarefaction.

Definition

The word osteoporosis literally means porous bones. It occurs when bones lose an excessive amount of their protein and mineral content, particularly calcium. Over time, bone mass, and therefore bone strength, is decreased. As a result, the bones become fragile and break easily. Even a sneeze or a sudden movement may be enough to break a bone in someone with severe osteoporosis.

Description

Osteoporosis is a serious public health problem. Some 28 million people in the United States are affected by this potentially debilitating disease, which is responsible for 1.5 million fractures (broken bones) annually. These fractures, which are often the first sign of the disease, can affect any bone, but the most common locations are the hip, spine, and wrist. Breaks in the hip and spine are of special concern because they almost always require hospitalization and major surgery; and may lead to other serious consequences, including permanent disability and even death.

To understand osteoporosis, it is helpful to understand the basics of bone formation. Bone is living tissue that's constantly being renewed in a two-stage process (resorption and formation) that occurs throughout life. In the resorption stage, old bone is broken down and removed by cells called osteoclasts. In the formation stage, cells called osteoblasts build new bone to replace the old. During childhood and early adulthood, more bone is produced than removed, reaching its maximum mass and strength by the mid-30s. After that, bone is lost at a faster pace than it's formed, so the amount of bone in the skeleton begins to slowly decline. Most cases of osteoporosis occur as an acceleration of this normal aging process. That is referred to as primary osteoporosis. The condition can also be caused by other disease processes or prolonged use of certain medications that result in bone loss; if so, it is called secondary osteoporosis.

Osteoporosis occurs most often in older people, especially in women after menopause. It affects nearly half of all adults, men and women, over the age of 75. Women, however, are five times more likely than men to develop the disease. They have smaller, thinner bones than men to begin with, and they lose bone mass more rapidly after menopause (usually around age 50), when they stop producing a bone-protecting hormone called estrogen. In the five to seven years following menopause, women can lose about 20% of their bone mass. By age 65 or 70, though, men and women lose bone mass at the same rate.

As an increasing number of men live longer, health professionals are increasingly aware that osteoporosis is an important health issue for men as well. In fact, men account for about 20% of all spinal fractures and up to 30% of all hip fractures due to osteoporosis.

Causes & Symptoms

A number of factors increase the risk of developing osteoporosis. They include:

• Age. Osteoporosis is more likely as people grow older and their bones lose strength.
• Sex. Women are more likely to have osteoporosis because they start out with less bone. They also lose bone tissue more rapidly as they age. While women commonly lose 30%–50% of their bone mass over their lifetimes, men lose only 20%–33% of theirs.
• Race. Caucasian and Asian women are most at risk for the disease, but African American and Hispanic women can get it too.
• Body type. Women with small bones or thin frames are more liable to develop osteoporosis.
• Early menopause. Women who begin menopause early because of heredity, surgery, or lots of physical exercise may lose large amounts of bone tissue early in life. Such conditions as anorexia and bulimia may also lead to early menopause and osteoporosis.
• Lifestyle. People who smoke or drink too much, or do not get enough exercise, have an increased chance of getting osteoporosis.
• Medications. Certain prescription medications may speed up the loss of bone. These drugs include methotrexate, cimetidine, corticosteroids, and heparin.
• Diet. Adults who do not get enough calcium or protein may be more likely to have osteoporosis. People who constantly diet are more prone to the disease.

Osteoporosis is often called the silent disease, because bone loss occurs without symptoms. People often don't know they have the disease until a bone breaks, frequently in a minor fall that wouldn't normally cause a fracture. A common occurrence is compression fractures of the spine. These can happen even after a seemingly normal activity, such as bending or twisting to pick up a light object. The fractures can cause severe back pain, but sometimes they go unnoticed. Either way, the vertebrae collapse down on themselves, and the person actually loses height. The hunchback appearance of many elderly women, sometimes called dowager's hump or widow's hump, is due to the effect of osteoporosis on the vertebrae.

Diagnosis

Certain types of doctors may have more training and experience than others in diagnosing and treating people with osteoporosis. These include a geriatrician, who specializes in treating the aged; an endocrinologist, who specializes in treating diseases of the body's endocrine system (glands and hormones); and an orthopedic surgeon, who treats fractures, such as those caused by osteoporosis.

Before making a diagnosis of osteoporosis, the doctor usually takes a complete medical history, conducts a physical examination, and orders x rays, as well as blood and urine tests, to rule out other diseases that cause loss of bone mass. The doctor may also recommend a bone density test. This is the only way to know for certain if osteoporosis is present. It can also show how far the disease has progressed.

Several diagnostic tools are available to measure the density of a bone. The ordinary x ray is one, though it's the least accurate for early detection of osteoporosis, because it doesn't reveal bone loss until the disease is advanced and most of the damage has already been done. Two other tools that are more likely to catch osteoporosis at an early stage are computed tomography scans (CT scans) and machines called densitometers, which are designed specifically to measure bone density.

The CT scan, which takes a large number of x rays of the same spot from different angles, is an accurate test, but uses higher levels of radiation than other methods. The most accurate and advanced of the densitometers uses a technique called DEXA (dual energy x-ray absorptiometry). With the DEXA scan, a double x-ray beam takes pictures of the spine, hip, or entire body. It takes about 20 minutes to do, is painless, and exposes the patient to only a small amount of radiation—about 1/50 that of a chest x ray.

In late 2001, Medicare began reimbursing for a test that measures bone resorption, an important measure for tracking a patient's response to osteoporosis therapy. The relatively inexpensive test measures a baseline amount, then compares amounts from later tests to track progress. The test consists of simple urine collection.

People should talk to their doctors about their risk factors for osteoporosis and if and when to have a bone density test. Ideally, women should have bone density measured at menopause and periodically afterward, depending on the condition of their bones. Men should be tested around age 65. Men and women with additional risk factors, such as those who take certain medications, may need to be tested earlier.

Treatment

Alternative treatments for osteoporosis focus on maintaining or building strong bones. They include nutritional and herbal therapies and homeopathy.

Nutritional Therapy

A healthful diet low in fats and animal products and containing whole grains, fresh fruits and vegetables, and calcium-rich foods (such as dairy products, dark-green leafy vegetables, sardines, salmon, and almonds), along with nutritional supplements (such as calcium, magnesium, and vitamin D) are important components of nutritional approaches to treating this disease.

Women should also eat more soy products such as tofu, soy burgers, or miso. Soy beans contain a substance called isoflavones which have estrogen-like activity. Isoflavones may help to increase bone density, alleviate hot flashes and other menopausal symptoms, lower the risk of cancer, and even reduce the risk of heart attacks. Natural hormone therapy, such as the use of soy products, is a safer alternative to synthetic estrogenic hormones, which may increase the risk of breast cancer.

In addition, women should avoid foods that may accelerate bone loss. They should avoid having too much salt in their diet, not only because salt raises the blood pressure but also because it may contribute to osteoporosis. They should also cut down on coffee, caffeinated sodas, and alcohol. High consumption of these beverages, studies have shown, are associated with accelerated drop in bone density and increase risk of bone fracture in old age. Caffeinated sodas are especially bad for the bones because in addition to containing caffeine, they also have high amounts of phosphoric acid. Phosphoric acid increases bone resorption, thus decreasing bone density.

Herbal Supplements

Herbal supplements for osteoporosis emphasize such calcium-containing plants as horsetail (Equisetum arvense), oat straw (Avena sativa), alfalfa (Medicago sativa), licorice (Glycyrrhiza glabra), marsh mallow (Althaea officinalis), and sourdock (Rumex crispus). There are, however, few data from clinical trials to support the use of these herbs.

Homeopathy

Homeopathic remedies for osteoporosis focus on treatments believed to help the body absorb calcium. These remedies may include such substances as Calcarea carbonica (calcium carbonate) or Silica (flint). Again, there are few data other than isolated case reports regarding the effectiveness of these remedies.

Allopathic Treatments

There are a number of good treatments for primary osteoporosis, most of them medications. For people with secondary osteoporosis, treatment may focus on curing the underlying disease.

Drugs

For most women who've gone through menopause, the best treatment for osteoporosis is hormone replacement therapy (HRT), also called estrogen replacement therapy. In addition to alleviating hot flashes, synthetic estrogens protect women against heart disease and they help to relieve and prevent osteoporosis. HRT increases a woman's supply of estrogen, which helps build new bone while preventing further bone loss.

Some women, however, do not want to take hormones because they have been linked to an increased risk of breast or uterine cancer. Other studies suggest that the risk is due to increasing age. Whether or not a woman takes hormones is a decision she should make carefully with her doctor. Most women take estrogen along with a synthetic form of progesterone, another female hormone. The combination helps protect against cancer of the uterus.

For people who can't or decide not to take estrogen, two other medications can be good choices. These are alendronate and calcitonin. Alendronate and calcitonin both stop bone loss, help build bone, and decrease fracture risk by as much as 50%. Alendronate (sold under the name Fosamax) is the first nonhormonal medication for osteoporosis ever approved by the FDA. It attaches itself to bone that's been targeted by bone-eating osteoclasts. It protects the bone from these cells. Osteoclasts help your body break down old bone tissue.

Calcitonin is a hormone that's been used as an injection for many years. A new version is on the market as a nasal spray. It too slows down bone-eating osteoclasts. Side effects of these drugs are minimal, but calcitonin builds bone by only 1.5% a year. Fosamax (alendronic acid) has proven safe in very large multi-year studies, and is now indicated for treatment of osteoporosis in most men. Several medications under study include other biphosphonates that slow bone breakdown (like alendronate), sodium fluoride, vitamin D metabolites, and selective estrogen receptor modulators.

Surgery

Unfortunately, much of the treatment for osteoporosis is for fractures that result from advanced stages of the disease. For complicated fractures, such as broken hips, hospitalization and a surgical procedure are required. In hip replacement surgery, the broken hip is removed and replaced with a new hip made of plastic, or metal and plastic. Despite often-successful surgeries, a large percentage of those who survive are unable to return to their previous level of activity, and many end up moving from self-care to a supervised living situation or nursing home. That's why prevention, getting early treatment, and taking steps to reduce bone loss are vital.

Expected Results

There is no cure for osteoporosis, but it can be controlled. Most people who have osteoporosis fare well once they get treatment. The medicines available now build bone, protect against bone loss, and halt the progress of this disease.

Prevention

Building strong bones, especially before the age of 35, and maintaining a healthy lifestyle are the best ways of preventing osteoporosis. To build as much bone mass as early as possible in life, and to help slow the rate of bone loss later in life:

Get Calcium in Foods

Experts recommend 1,500 milligrams (mg) of calcium per day for adolescents, pregnant or breast-feeding women, older adults (over 65), and postmenopausal women not using hormone replacement therapy. All others should get 1,000 mg per day. Foods are the best source for this important mineral. Milk, cheese, and yogurt have the highest amounts. Other foods that are high in calcium are green leafy vegetables, tofu, shellfish, Brazil nuts, sardines, and almonds.

Take Calcium Supplements

Many people, especially those who don't like or can't eat dairy foods, don't get enough calcium in their diets and may need to take a calcium supplement. Supplements should be taken with meals and accompanied by six to eight glasses of water a day.

Get Vitamin D

Vitamin D helps the body absorb calcium. People can get vitamin D from sunshine with a quick (15–20 minute) walk each day or from foods such as liver, fish oil, and vitamin D fortified milk. During the winter months it may be necessary to take supplements. Four hundred mg daily is usually the recommended amount.

Avoid Smoking and Alcohol

Smoking reduces bone mass, as does heavy drinking. To reduce risk, do not smoke; and limit alcoholic drinks to no more than two per day. An alcoholic drink is 1.5 ounces of hard liquor, 12 ounces of beer, or 5 ounces of wine.

Exercise Regularly

Exercising regularly builds and strengthens bones. Weight-bearing exercises, in which bones and muscles work against gravity, are best. These include aerobics, dancing, jogging, stair climbing, tennis, walking, and lifting weights. People who have osteoporosis may want to attempt gentle exercise, such as walking, rather than jogging or fast-paced aerobics, which increase the chance of falling. Try to exercise three to four times per week for 20–30 minutes each time.

Resources

Books

Brown, Susan E. Better Bones, Better Body: A Comprehensive Self-Help Program for Preventing, Halting and Overcoming Osteoporosis. New Canaan, CT: Keats Publishing, 1996.

The Burton Goldberg Group. Alternative Medicine: The Definitive Guide. Fife, WA: Future Medicine Publishing, 1995.

Hammond, Christopher. The Complete Family Guide to Homeopathy: An Illustrated Encyclopedia of Safe and Effective Remedies. New York: Penguin Books, 1995.

Murray, Michael and Joseph Pizzorno. Encyclopedia of Natural Medicine. Rocklin, CA: Prima Health, 1998.

Notelovits, Morris, with Marsha Ware and Diana Tonnessen. Stand Tall! Every Woman's Guide to Preventing and Treating Osteoporosis, 2nd ed. Gainesville, FL: Triad Publishing Co., 1998.

Zand, Janet, Allan N. Spreen, and James B. LaValle. Smart Medicine for Healthier Living: A Practical A-to-Z Reference to Natural and Conventional Treatments for Adults. Garden City Park, NY: Avery Publishing Group, 1999.

Periodicals

"Brittle bone relief for men." Chemist and Druggist (December 15, 2001):25.

"Test Gains Mandatory National Medicare Coverage." Health and Medicine Week (December 31, 2001):29.

Organizations

Arthritis Foundation. 1330 W. Peachtree St. PO Box 7669. Atlanta, GA 30357-0669. (800) 283-7800. http://www.arthritis.org.

National Osteoporosis Foundation. Suite 500, 1150 17th Street, NW. Washington, DC 20036-4603. (800) 223-9994. http://www.nof.org.

[Article by: Mai Tran; Teresa G. Odle]

Osteoporosis (literally "porous bone") is a condition characterized by bone fragility and fracturing. The World Health Organization (WHO) defines osteoporosis as a 25 percent reduction of bone mineral density (BMD) compared to that of a healthy young adult female.

Eight million Americans have osteoporosis, and over 20 million have osteopenia (thin bones, or a loss of 10 to 25% of bone mineral density). Osteoporosis is most prevalent in Caucasians, less prevalent in Hispanics, and least prevalent in African Americans. Key predisposing factors are early menopause and a family history of osteoporosis. Other medical, psychological, and social factors may also contribute to the condition.

Osteoporosis commonly leads to fractures. Medical, social, and environmental factors that predispose people to osteoporosis-related fractures include impairment of hearing, vision, balance and cognition; debilitating illnesses; medications; postoperative conditions; and unsafe environments. In the United States, one of three females over age sixty-five will have at least one vertebral fracture. The ratio of female to male fractures of a hip is 2.5 to one. Two hundred and fifty thousand hip or wrist fractures and 500,000 vertebral fractures occur annually in the United States. Up to 15 percent of hip fractures will result in death within one year, and one of three survivors become long-term nursing home residents. The annual cost of osteoporosis in the United States is estimated to be as high as $18 million and is projected to reach $240 million by the year 2040.

There are several methods to measure bone mineral density for osteoporosis detection. The most precise is dual energy X-ray absorptiometry (DXA) of the hip. Blood and urine tests for bone resorption and formation are also used to help measure the response to therapy.

The four components of treatment are nutrition, medication, exercise, and safety. Nutritional factors are particularly important during childhood and adolescence when the bones are growing. Key components are calcium and vitamin D, supplemented by magnesium; and vitamins C and K for individuals with chronic diarrhea or on a low-vegetable diet.

Hormonal therapies—estrogens for postmenopausal females and testosterone for hypogonadal males—are widely utilized. Estrogens may be contraindicated by breast or uterine cancer or by susceptibility to vascular clotting, and prostatic disorders may preclude the use of testosterone. Bisphosphonates are potent antiresorptive drugs that can yield reductions in hip and vertebral fracturing. Use of calcitonin, another antiresorptive drug, has also shown reductions in vertebral fracturing.

Exercise and safety are essential components of fracture prevention. Vigorous weight-bearing activities are beneficial but not feasible for the elderly or infirm. Walking has not proved efficacious. Resistive exercises increase the muscle strength and bone mineral density essential to fracture prevention. Balance–enhancing activities such as dancing, careful attention to minimizing hazards in the home and work environments, and selective use of padded hip protectors for the aged and infirm all help reduce the risk of osteoporosis-related fractures.

Osteoporosis is a major and growing public health concern. Appropriate screening to identify those who are susceptible, accurate diagnosis of osteoporosis and related disorders, and prompt institution and monitoring of appropriate therapies are all essential to minimize the risks of fracture and the attendant mortality and morbidity.

(SEE ALSO: Hip Fractures)

Bibliography

Melton, L. J., III (2000). "Perspective: Who Has Osteoporosis? A Conflict Between Clinical and Public Health Perspectives." Journal of Bone and Mineral Research 15(12):2309–2314.

Scheiber, L. B., II, and Torregrosa, L. (1988). "Evaluation and Treatment of Postmenopausal Osteoporosis." Seminars in Arthritis and Rheumatism 27(4):245–261.

Swezey, R. L. (2000). "Osteoporosis: Diagnosis, Pharmacological, and Rehabilitation Therapies." Critical Reviews in Physical and Rehabilitation Medicine 12(3):229–269.

Youm, T.; Koval, K. J.; and Zuckerman, J. D. (1999). "The Economic Impact of Geriatric Hip Fractures." American Journal of Orthopedics 28(7):423–428.

— ROBERT L. SWEZEY

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For more information on osteoporosis, visit Britannica.com.

brittle bone disease

A group of diseases characterized by decreased bone mineral content that increases bone porosity, and causes them to become more brittle and more inclined to fracture. Osteoporosis is an age-related disease, which primarily affects post-menopausal women. Physical exercise when young can reduce the risk of developing the disease in later life. Moderate weight-bearing exercise (e.g. dancing, walking, and tennis) stimulates the deposition of calcium, strengthening bones. Women with osteoporosis should avoid contact sports and high-impact exercise which puts undue stress on bones and joints. Sit-ups are also harmful because of the stress they impose on vertebrae. A premenopausal diet rich in calcium and vitamin D also reduces the risk of osteoporosis.

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(os-tee-oh-puh-roh-sis)

A softening of the bones that gradually increases and makes them more fragile. It is caused by the gradual loss of the mineral calcium, which helps make bones hard. Osteoporosis occurs most often in elderly women.

Many experts now believe that osteoporosis can be prevented through regular exercise, mineral supplements, and a diet high in calcium.

A pathological loss of bone but the remaining bone is structurally normal. There is an imbalance in bone formation and resorption in favor of resorption. Bone becomes light and porous and fragile so that it fractures easily. It is associated with general undernutrition rather than specific nutritional deficiencies. Other causative factors are disuse, senility, lactation, weightlessness.

• disuse o. — that occurring when the normal laying down of bone is slowed because of lack of the normal stimulus of functional stress on the bone.
• post-traumatic o. — loss of bone substance after an injury in which there is nerve damage, sometimes due to decreased blood supply caused by the neurogenic insult, or to disuse secondary to pain.

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Dansk (Danish)
n. - osteoporosis, knogleskørhed

Nederlands (Dutch)
osteoporose, ontkalking van botten, breuk veroorzaakt door ontkalking

Français (French)
n. - ostéoporose

Deutsch (German)
n. - Osteoporose

Ελληνική (Greek)
n. - (παθολ.) οστεοπόρωση

Italiano (Italian)
osteoporosi

Português (Portuguese)
n. - osteoporose (f)

Русский (Russian)
остеопороз

Español (Spanish)
n. - osteoporosis

Svenska (Swedish)
n. - osteoporis (benskörhet)

中文（简体）(Chinese (Simplified))
骨质疏松症

中文（繁體）(Chinese (Traditional))
n. - 骨質疏鬆症

한국어 (Korean)
n. - 골다공증

日本語 (Japanese)
n. - 骨多孔症, 骨粗鬆症

العربيه (Arabic)
‏(الاسم) مرض هشاشه العظام‏

עברית (Hebrew)
n. - ‮בריחת סידן, אוסטיאופורוזיס‬

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