Osteoporosis

Osteoporosis 

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 44 million people in the United States are at risk for 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 is 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 is 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, which is referred to as primary osteoporosis. The condition also can be caused by other disease processes or prolonged use of certain medications that result in bone loss. If so, this is called secondary osteoporosis.

Osteoporosis occurs most often in older people and in women after menopause. It affects nearly half of men and women over the age of 75. Women are about 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 is more awareness that osteoporosis is an important health issue for them as well. In fact, a 2003 report noted that one in every eight men over age 50 will suffer a hip fracture as a result of osteoporosis.

Causes and symptoms

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

Osteoporosis is often called the "silent" disease, because bone loss occurs without symptoms. People often do not know they have the disease until a bone breaks, frequently in a minor fall that would not 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 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 this 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 exam, and orders x rays, as well as blood and urine tests, to rule out other diseases that cause loss of bone mass. The doctor also may recommend a bone density test. This is the only way to know for certain if osteoporosis is present. It also can show how far the disease has progressed.

Several diagnostic tools are available to measure bone density. The ordinary x ray is one, though it is the least accurate for early detection of osteoporosis, because it does not 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 one-fiftieth that of a chest x ray.

Doctors do not routinely recommend the test, partly because access to densitometers is still not widely available. People should talk to their doctors about their risk factors for osteoporosis and if, and when, they should get the 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

There are a number of good treatments for primary osteoporosis, most of them medications. Two medications, alendronate and calcitonin (in nose spray form), have been approved by the Food and Drug Administration (FDA). They provide people who have osteoporosis with a variety of choices for treatment. For people with secondary osteoporosis, treatment may focus on curing the underlying disease.

Drugs

For many women who have gone through menopause, the treatment of choice for osteoporosis has been hormone replacement therapy (HRT), also called estrogen replacement therapy. Many women choose HRT when they undergo menopause to alleviate symptoms such as hot flashes, but hormones increase a woman's supply of estrogen, which helps build new bone, while preventing further bone loss. A 2002 report from a large clinical trial called the Women's Health Initiative helped verify HRT's positive effects in preventing osteoporosis in postmenopausal women.

However, the WHI also revealed several risks with taking combined HRT (estrogen and progesterone). In fact, the trial was stopped early because the incidence of invasive breast cancer in women on HRT passed a threshold that was considered too risky for the benefits they were receiving. The study also found that the women on combined hormone therapy were at increased risk for coronary heart disease and stroke. Whether or not a woman takes hormones and for how long is a decision she should make carefully with her doctor. Women should talk to their doctors about personal risks for osteoporosis, as well as their risks for heart disease and breast cancer.

Since estrogen may no longer be recommended for prevention of osteoporosis, selective use of alendronate and calcitonin are possible alternatives. 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 has been targeted by bone-eating osteoclasts, protecting the bone from these cells. Osteoclasts help the body break down old bone tissue.

Calcitonin is a hormone that has 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, which may not be enough for some women to recover the bone they lose. Fosamax has proven safe in large, multi-year studies, but not much is known about the effects of its long-term use. Several medications under study include other bisphosphonates that slow bone breakdown (like alendronate), sodium fluoride, vitamin D metabolites, and selective estrogen receptor modulators. Some of these treatments are already being used in other countries, but have not yet been approved by the FDA for use in the United States.

In early 2003, a report announced that the FDA had recently approved the first drug that could form bone in osteoporosis patients. The drug is a form of the human parathyroid hormone called teriparatide. It shows promise for those patients at highest risk for fracture from the disease. There are some patients who cannot use the drug, so all considering the new treatment must check with their physician and may need to undergo bone densitometry scans or other testing.

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. Though the surgery itself is usually successful, complications of the hip fracture can be serious. Those individuals have a 5-20% greater risk of dying within the first year following the injury than do others in their age group. A large percentage of those who survive are unable to return to their previous level of activity, and many move self-care to a supervised living situation or nursing home. That is why getting early treatment and taking steps to reduce bone loss are vital.

Alternative treatment

Alternative treatments for osteoporosis focus on maintaining or building strong bones. A healthy 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), and weight-bearing exercises are important components of both conventional prevention and treatment strategies and alternative approaches to the disease. In addition, alternative practitioners recommend a variety of botanical medicines or herbal supplements. Herbal supplements designed to help slow bone loss emphasize the use of calcium-containing plants, such as horsetail (Equisetum arvense), oat straw (Avena sativa), alfalfa (Medicago sativa), licorice (Glycyrrhiza galbra), marsh mallow (Althaea officinalis), and yellow dock (Rumex crispus). Homeopathic remedies focus on treatments believed to help the body absorb calcium. These remedies are likely to include such substances as Calcarea carbonica (calcium carbonate) or silica. In traditional Chinese medicine, practitioners recommend herbs thought to slow or prevent bone loss, including dong quai (Angelica sinensis) and Asian ginseng (Panax ginseng). Natural hormone therapy, using plant estrogens (from soybeans) or progesterone (from wild yams), may be recommended for women who cannot or choose not to take synthetic hormones.

Prognosis

There is no cure for osteoporosis, but it can be controlled. Most people who have osteoporosis fare well once they receive 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 to prevent 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, doctors advise:

Getting calcium from foods

Experts recommend 1,500 milligrams (mg) of calcium per day for adolescents, pregnant or breastfeeding 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.

Taking calcium supplements

Many people, especially those who do not like or can not eat dairy foods, do not get enough calcium in their diets and may need calcium supplements. Supplements vary in the amount of calcium they contain. Those with calcium carbonate have the most amount of useful calcium. Supplements should be taken with meals and accompanied by six to eight glasses of water a day.

Getting 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.

Avoiding smoking and alcohol

Smoking reduces bone mass, as does heavy drinking. Avoiding smoking and limiting alcoholic drinks to no more than two per day reduces risks. An alcoholic drink is one-and-a-half ounces of hard liquor, 12 ounces of beer, or five ounces of wine.

Exercise

Exercising regularly builds and strengthens bones. Weight-bearing exercises—where 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. Exercising three to four times per week for 20-30 minutes each time helps.

Resources

Periodicals

Doering, Paul L. "Treatment of Menopause Post-WHI: What Now?" Drug Topics April 21, 2003: 85.

Elliott, William T. "HRT, Estrogen, and Postmenopausal Women: Year-old WHI Study Continues to Raise Questions." Critical Care Alert July 2003: 1.

LoBuono, Charlotte. "New Osteoporosis Drug is First to Form Bone." Drug Topics January 6, 2003: 24.

"More Men at Osteoporosis Risk than Commonly Believed." Tufts University Health and Nutrition Letter August 2003: 8.

Nelson, Heidi D. "Postmenopausal Osteoporosis and Estrogen." American Family Physician August 15, 2003: 606.

"Osteoporosis Gene Identified." Diagnostics and Imaging Week March 13, 2003 4.

"Three Out of Four Women Currently Taking Prescriptions for Osteoporosis Are Not Receiving Full Treatment, According to Recent Data from a National Physician Audit." Drug Cost Management Report January 2003: 11.

Key terms

Alendronate — A nonhormonal drug used to treat osteoporosis in postmenopausal women.

Anticonvulsants — Drugs used to control seizures, such as in epilepsy.

Biphosphonates — Compounds (like alendronate) that slow bone loss and increase bone density.

Calcitonin — A hormonal drug used to treat postmenopausal osteoporosis

Estrogen — A female hormone that also keeps bones strong. After menopause, a woman may take hormonal drugs with estrogen to prevent bone loss.

Glucocorticoids — Any of a group of hormones (like cortisone) that influence many body functions and are widely used in medicine, such as for treatment of rheumatoid arthritis inflammation.

Hormone replacement therapy (HRT) — Also called estrogen replacement therapy, this controversial treatment is used to relieve the discomforts of menopause. Estrogen and another female hormone, progesterone, are usually taken together to replace the estrogen no longer made by the body.

Menopause — The ending of a woman's menstrual cycle, when production of bone-protecting estrogen decreases.

Osteoblasts — Cells in the body that build new bone tissue.

Osteoclasts — Cells that break down and remove old bone tissue.

Selective estrogen receptor modulator — A hormonal preparation that offers the beneficial effects of hormone replacement therapy without the increased risk of breast and uterine cancer associated with HRT.

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osteoporosis /os·teo·po·ro·sis/ (-por-o´sis) abnormal rarefaction of bone; it may be idiopathic or occur secondary to other diseases.osteoporot´ic

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posttraumatic osteoporosis  loss of bone substance following a nerve-damaging injury, sometimes due to an increased blood supply caused by the neurogenic insult, or to disuse secondary to pain; a component of reflex sympathetic dystrophy.

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os·te·o·po·ro·sis (st--p-rss) n. pl. os·te·o·po·ro·ses (-sz) A disease characterized by decrease in bone mass and density, occurring especially in postmenopausal women, resulting in a predisposition to fractures and bone deformities such as vertebral collapse. oste·o·po·rotic (-rtk) adj.

osteoporosis Top: detail of normal femur Bottom: detail of osteoporotic femur

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osteoporosis,

n bone disorder characterized by porosity, low mass, and structural deterioration, which leads to fragility and increased likelihood of fracture, especially of the spine, hip, and wrist.

Osteoporosis.

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osteoporosis (os´tēōpôrō´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 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.

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osteoporosis

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.

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disuse osteoporosis

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 osteoporosis

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.