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Osteoporosis

WHAT IS OSTEOPOROSIS?

Osteoporosis is a disease of the skeleton in which bones become brittle and prone to fracture. In other words, the bone loses density. Osteoporosis is diagnosed when bone density has decreased to the point where fractures will happen with mild stress. [ For determining this point, see how is Osteoporosis Diagnosed, below.]

Until a healthy person is around 40, the process of breaking down and building up bone by cells called osteoclasts and osteoblasts is a nearly perfectly coupled system, with one phase stimulating the other. [For a brief description of this process see Box The Bones, below.] As a person ages, however, or in the presence of certain conditions, this system breaks down and the two processes become out of sync. The reasons why this occurs during aging are not clear. Some individuals have a very high turnover rate of bone; some have a very gradual turnover, but the breakdown of bone eventually overtakes the build-up.

THE BONES

The Function of Bones

The skeleton has a dual function:

It provides structural support for muscles and organs.
It also serves as a depot for the body's calcium and other essential minerals, such as phosphorus and magnesium.

The skeleton holds 99% of the body's calcium. The remaining one percent is freed to circulate in the blood and is essential for crucial bodily functions, ranging from muscle contraction to nerve function to blood clotting.

Bone Turnover: the Breakdown and Growth of Bones

Like other organs in the body, bone tissue is constantly being broken down and reformed again. This turnover is necessary for growth, for repair of minor damage that occurs from everyday stress, and for the maintenance of a properly functioning body. Two essential cells are involved in this process:

Osteoclast cells are formed from certain blood cells and are responsible for the breakdown, or resorption, of the skeleton. These cells dig holes into the bone and release the small amounts of calcium into the bloodstream that are necessary for other vital functions.
Osteoblast cells are produced by bone cells and are the bone builders. They rebuild the skeleton, first by filling in the holes with collagen, and then by laying down crystals of calcium and phosphorus.

Each year, approximately 10% to 30% of the adult skeleton is remodeled in this way. The osteoclast-osteoblast balance is controlled by a complex mix of hormones and chemical factors.

Primary Osteoporosis

There are two primary kinds of osteoporosis: type I and type II.

Type I. Type I, or high-turnover, osteoporosis occurs in 5% to 20% of women, most often between the ages of 50 and 75 because of the sudden postmenopausal decrease in estrogen levels, which results in a rapid depletion of calcium from the skeleton. It is associated with fractures that occur when the vertebrae compress together causing a collapse of the spine, and with fractures of the hip, wrist, or forearm caused by falls or minor accidents. Type 1 accounts for the significantly greater risk for osteoporosis in women than in men.
Type II. Type II, or low turnover, osteoporosis (also known as age-related or senile osteoporosis) results when the process of resorption and formation of bone are no longer coordinated, and bone breakdown overcomes bone building. (This occurs with age in everyone to some degree.) Type II osteoporosis affects both men and women and is primarily associated with leg and spinal fractures. Older women can have both type I and type II osteoporosis.

The determining factor for the actual existence of osteoporosis, whether type I or type II, is the amount of calcium left in the skeleton and whether it places a person at risk for fracture. [ See Box Determining Osteoporosis.] Someone who has exceptionally dense bones to begin with will probably never lose enough calcium to reach the point where osteoporosis occurs, whereas a person who has low bone density could easily develop osteoporosis despite losing only a relatively small amount of calcium.

Secondary Osteoporosis

Secondary osteoporosis is caused by other conditions, such as hormonal imbalances, certain diseases, or medications (such as corticosteroids). Details on the many other causes of secondary disease are included throughout this report.

Determining Osteoporosis

Osteoporosis is diagnosed when bone density has decreased to the point where fractures will happen with mild stress, the so-called fracture threshold. This threshold is defined by the World Health Organization (WHO) and is determined as follows:

Bone mass density (BMD) is measured, usually in the hipbone, using testing instruments. [ See Measuring Bone Densit y under How Is Osteoporosis Diagnosed?]
The patient's BMD is compared to normal bone density. This is defined by WHO as the average BMD in the hipbones of premenopausal Caucasian women. (This group is used as the basis for the norm because of their high risk.)
The health professional then estimates the patient's risk for fracture by determining her standard deviation from this norm. Each standard deviation below this norm is equivalent to a 2.6-fold increased risk in hip fracture.

In general, the following measurements are used to determine osteoporosis and degrees of risk:

1 or less standard deviations (SDs) indicate normal BMD.
Between 1 and 2.5 SDs below normal defines osteopenia, which is low bone density.
Greater than 2.5 SDs defines osteoporosis.
Greater than 2.5 SDs plus risk factors for fracture defines severe osteoporosis. Risk factors, including low weight, smoking status, risks for falling, and especially a history of previous fractures. For example, in women 65 years old with low bone density but no other adverse factors, the risk for fracture is 4.3% in one year and 28.6% over five years. In similar women with a previous fracture, the probability of fracture at one year is 11% and at five years is 71.8%.

Note: Because the standards are based on Caucasian women, they do not necessarily apply to men, children, or to non-Caucasian women. For example, men have a lower risk for fracture at the same SDs as women. Researchers are attempting to establish risk guidelines for these groups as well.

WHAT CAUSES OSTEOPOROSIS?

Because the patterns of reforming and resorbing bone often vary from patient to patient, experts believe a number of different factors account for this problem. Important chemicals (such as estrogen, parathyroid, and vitamin D) and blood factors that affect cell growth are involved with this process. Changes in levels of any of these factors could play a role in the development of osteoporosis.

The Role of Sex Hormones in Bone Breakdown

Although ordinarily associated with women, sex hormones play a role in osteoporosis in both genders, most likely by controlling the birth and duration of life of both osteoclasts (bone breakers) and osteoblasts (bone builders).

Women and Estrogen. Experts are still puzzled by the rapid decline in bone density after menopause when a woman's ovaries stop producing estrogen. Estrogen comes in several forms:

The most potent form of estrogen is estradiol. Estradiol deficiency appears to be a very strong factor in the development of osteoporosis.
The other important but less powerful estrogens are estrone and estriol. In one study, high levels of estrone were associated with high risk for spinal fracture, but the researchers said these results might have been due to chance.

Most of the estrogens in the body are produced by the ovaries, but they can also be formed by other tissues, such as body fat, skin, and muscle. After menopause, some amounts of estrogen continue to be manufactured in the peripheral body fat. And even though the ovaries have stopped producing estrogens directly, they continue to be a source of the male hormone testosterone, which converts into estradiol.

Estrogen may have an impact on bone density in various ways:

Estrogen's most important effect on osteoporosis appears to be prevention of bone break down (resorption). Some research suggests that estrogen may control the life span of osteoclasts, the cells responsible for bone breakdown.
One study reported that part of estrogen's beneficial actions may involve maintaining normal levels of vitamin D, an important nutrient in bone protection.

Men and Androgens and Estrogen. In men, the most important male hormone (androgen) is testosterone, which is produced in the testes. Other androgens are produced in the adrenal glands. Androgens are converted to estrogen in various parts of a man's body, including bone.

Studies in 2000 and 2001 have suggested that the loss of estrogen as well as testosterone may contribute to bone loss in elderly men. In one 2000 study, elderly men were first given a drug that blocked their normal hormones and then were given estrogen and testosterone patches. When the estrogen patch was removed, the bone breakdown process accelerated. When both patches were removed, the number of the bone building cells (the osteoblasts) decreased. In other words, both hormones appeared to be integral to bone function in men.

The Roles of Vitamin D and Parathyroid Hormone

A 1999 study reported that a significant number of postmenopausal women with hip fracture had lower levels of vitamin D and higher levels of parathyroid hormone (PTH) than two comparison groups of women with and without osteoporosis who did not have hip fractures.

Vitamin D is a vitamin and a hormone. It is essential for the absorption of calcium into the bone and for normal bone growth. Lower levels result in impaired calcium absorption, which in turn causes an increase in PTH.
High persistent levels of PTH stimulate bone resorption (bone loss). In one study, women with low estrogen levels (as occurs after menopause) were even more sensitive to the resorptive action of PTH.

Genetic Factors

A number of studies on twins and family members have strongly suggested that genetic factors help determine bone density. Some examples include the following:

Of particular interest are genetic factors that affect vitamin D, which is a critical nutrient for calcium absorption in the body.
A 1998 study has introduced another suspect, a genetic mutation that controls production of a type of collagen, a structural protein that is critical in bone formation.
Many studies are currently looking at abnormalities in genes that may cause deficiencies in estrogen receptors , molecules that help estrogen work on cells. Estrogen is important in maintaining bone density in both men and women.
An interesting 2000 study on mice suggests that the enzyme leptin may play a role in bone build-up and loss. Mice that have genetic mutations causing them to be deficient in leptin (the so-called "obesity gene") are not only obese but they also have extremely strong bones. Leptin is a hormone produced in the brain and is associated with thinness in high levels and obesity in low levels. If leptin proves to affect bone density, by implication the brain becomes an important player in osteoporosis.

Some Causes of Secondary Osteoporosis

Predisposing Medical Conditions. Osteoporosis can be secondary to a number of other conditions, including alcoholism, hyperthyroidism, chronic liver or kidney disease, celiac disease, scurvy, rheumatoid arthritis, leukemia, cirrhosis, gastrointestinal diseases, vitamin D deficiency, hypogonadism (impaired development of reproductive organs), lymphoma, and rare genetic disorders, such as Marfan's and Ehlers-Danlos syndrome. Hyperparathyroidism is a condition where the body either underproduces or doesn't recognize a hormone called parathyroid hormone. It may occur spontaneously or as a result of other diseases such as cancer.

Corticosteroids. More than 30 million Americans have disorders that are commonly treated using corticosteroids (also called glucocorticoids or steroids). It has been known for some time that oral glucocorticoid therapy reduces bone mass, although studies have been mixed on the effects of inhaled steroids on bone loss. Important studies in 2001 have strongly suggested that postmenopausal women (but not premenopausal women) are at risk for bone loss and possibly for fractures from inhaled steroids. The risk is higher with increasing doses, and is still lower than with oral steroids. (Children on inhaled steroids may have temporary impaired growth, but they do not appear to be at risk for bone loss.)

Other Medications. Other agents that increase the risk for bone loss include heparin, progestin without estrogen (such as Depo-Provera or other progestin-based contraceptives), hormonal agents that suppress estrogen (such as gonadotropin-releasing hormone agonists), seizure medications, and high-dose loop diuretics.

WHAT ARE THE SYMPTOMS OF OSTEOPOROSIS?

Many confuse osteoporosis with arthritis and believe they can wait for symptoms, such as swelling and joint pain, to occur before seeing a doctor. It should be stressed that the mechanisms that cause arthritis are entirely different from those in osteoporosis, which usually becomes quite advanced before its symptoms appear.

All too often osteoporosis becomes apparent in dramatic fashion: a fracture of a vertebra (back bone), hip, forearm, or any bony site if sufficient bone mass is lost. These fractures frequently occur after apparently minor trauma, such as bending over, lifting, jumping, or falling from the standing position.

In the latter stages of the disease, pain, disfigurement, and debilitation are common. Early spinal compression fractures may go undetected for a long time, but after a large percentage of calcium has been lost, the vertebrae in the spine start to collapse, gradually causing a stooped posture called kyphosis, or commonly, a dowager's hump. Although this is usually painless, patients may lose as much as 6 inches in height.

HOW SERIOUS IS OSTEOPOROSIS?

Fractures

Osteoporosis is a major cause of disability and death in the elderly, mostly due to subsequent fractures. Women at highest risk for fractures are those with low bone density plus a history of fractures, particularly nonviolent fractures.

Each year, there are an estimated 500,000 spinal fractures, 300,000 hip fractures, 200,000 broken wrists and 300,000 fractures of other bones. About 80% of these fractures occur after relatively minor falls or accidents. Often, apparently, not even doctors recognize the link between fractures and osteoporosis. In one Mayo Clinic study of women with an average age of 45, doctors did not provide advice about osteoporosis to 71% of those who sustained fractures.

Between 25% and 60% of women over 60 years old develop spinal compression fractures. By age 90, one third of all women and 17% of men have sustained a hip fracture. Between 35% and 50% of these patients lose their previous walking capacity after a fracture, between 20% and 15% become house bound, and as many as 20% require institutionalization.

Higher Mortality Rates

Even worse, an estimated 2.8% of 50-year old Caucasians and between 14% and 36% of elderly people die within a year of hip fracture. The increased mortality rates after major fractures are associated with poor general health and appear to be higher in older men than older women. One 1999 study reported that even tiny spinal fractures that go unnoticed by physicians in older female patients are associated with higher mortality rates, mostly from serious illnesses, including lung disease and cancer. Kyphosis, which occurs with severe osteoporosis, puts pressure on the lungs and is probably the major factor in the higher rates of death from lung disease. The connection with a higher risk for cancer is unclear. Small fractures may be a sign of cancer rather than a cause, but there is some indication that vertebral fractures and certain cancers may share a common cause in some cases. (Minor fractures in younger women pose no such risk.) Another study also reported an association between osteoporosis and a higher-than-average decline in mental functioning in women; both conditions may be due to estrogen deficiency.

WHO GETS OSTEOPOROSIS?

Eight million women and two million men already have the disease. Eighteen million more are at risk.

Specific Risk Factors for Low Bone Density in Women

An estimated 28 million US adults have osteoporosis or are at risk for osteoporosis in the hip. After age 65, about 30% of women have osteoporosis, and nearly all of them are unaware of their condition. Events associated with estrogen deficiencies are the primary risk factors for osteoporosis in women.

Natural and Surgical Causes of Estrogen Deficiency.

Menopause. Within the five years after menopause, the risk for fracture increases dramatically. Fractures occurring during this period are more likely to occur in the wrist or spine than the hip, but their occurrence is a strong predictor of later severe osteoporosis and hip fracture.
Surgical removal of ovaries.
Missing a periods for three months or longer.
Never giving birth.

Paradoxically, pregnancy and nursing do not increase the risk for osteoporosis even though during those times calcium is diverted from the mother to the baby. A factor believed to be associated with reduced bone density is elevated at a constant level during nursing, but as the baby is weaned, levels of the factor decline and bone formation is restored.

Female Athlete Triad. In the small community of athletes, excessive exercise plays a major role in many cases of anorexia (and, to a lesser degree, bulimia), which in turn increases the risk for low estrogen levels and bone loss. The term "female athlete triad" in fact, is now a common and serious disorder facing young female athletes and dancers and describes the combined presence of the following problems:

Eating disorders.
Amenorrhea (absence or irregular menstruation). Evidence is mounting that overly restricting calories may be more important than low weight in causing menstrual problems. Studies suggest that amenorrhea occurs even in women with normal weight if they severely diet.
Osteoporosis. Bone loss, on the other hand, appears to be related to low weight. The more severe the weight loss, the more bone is lost.

In one study, female athletes who consumed a high-fat diet (35% of daily calories) performed longer and with greater intensity than those with a standard athletic low-fat diet (27% of daily calories). And such a diet appeared to be more estrogen-protective.

Specific Risk Factors for Bone Density Loss in Men

A 2000 statement by an expert panel of National Institutes of Health asserted "Osteoporosis, once thought to be a natural part of aging among women, is no longer considered... gender-dependent." Men start with higher bone density and lose calcium at a slower rate than women, which is why their risk is far lower. Nevertheless, after age 50, bone loss increases, and, according to one 2000 study, more rapidly than previously thought. Men have a 6% risk for hip fracture and between 16% and 25% risk for any fractures related to osteoporosis. And the actual numbers of osteoporosis and fractures in men is bound to grow as baby boomers age. Some risk factors include the following:

Hormonal deficiencies, including both testosterone and estrogen, which occur in older men (although much more slowly than in women). Estrogen deficiencies may also a play a major role in osteoporosis in older men. It is unknown yet what normal estrogen levels are in men.
Medical conditions that can reduce testosterone levels, such as prostate cancer treatments, testicular surgery, and mumps.
Hypogonadism, which is a severe deficiency in the primary hormone that signals the process leading to the release of testosterone and other important reproductive hormones.

Risk Factors in Children and Adolescents

The maximum density that bones achieved during the growing years is a major factor in whether a person goes on to develop osteoporosis. Persons, usually women, who never develop peak bone mass in early life are at high risk for osteoporosis later on. Children at risk for low peak bone mass include the following:

Children born prematurely.
Children with anorexia nervosa (more common in girls).
Young, highly competitive athletes.
Children who take oral corticosteroid drugs. (Inhaled steroids, which are common in asthma treatments, appear to pose a very low risk or none at all.)
Children with certain medical conditions, including cystic fibrosis, inflammatory bowel disease, and celiac disease.
Children with delayed puberty.

Although to a large extent genetics predict bone health, exercise and good nutrition during the first three decades of life, when peak bone mass is reached, are still benign safeguards against osteoporosis (and countless other health problems).

Risk Factors for Osteoporosis in Both Genders

Dietary Factors. Diet plays an important role in preventing and speeding up bone loss in men and women. Deficiencies in or excessive amounts of certain nutrients may increase the risk for low bone density and osteoporosis. Calcium and vitamin D deficiencies, of course, are important factors in the risk for osteoporosis. Of note in this regard was a 2000 Italian study, which reported that postmenopausal women who dieted to lower cholesterol levels by reducing dairy products put themselves at risk for bone loss. Eating low-fat dairy products or taking calcium supplements can offset this risk without increasing cholesterol levels. [For a more detailed discussion of both positive and negative dietary factors see What Lifestyle Changes can Help Prevent Further Progression of Osteoporosis?]

Too Little Exercise. Lack of exercise can put people at risk for osteoporosis. Inactivity that results in weak thigh muscles and poor balance particularly puts people at risk for fracture. One study conducted in a rural part of Turkey where women did all the physical work showed that men had a higher rate of fractures than women.

Being Underweight. Being underweight is a risk factor for osteoporosis in men as well as women. (Shortness, thinness, and narrow hips all increase the risk for fracture in people with low bone density.)

Lack of Sunlight. The photochemical effect of sunlight on the skin is a primary source for vitamin D. Bone formation peaks in the summer and bone breakdown increases in the winter. People who avoid sun exposure to prevent skin cancer may be at risk for vitamin D deficiency, particularly it they are elderly. (One 2000 study of three different countries confirmed a higher winter-risk for hip fractures even in countries without snowfall.)

Smoking. Women who smoke, particularly after menopause, have a significantly greater chance of spine and hip fractures than those who don't smoke. Men who smoke also have less bone density.

Cultural Differences. A number of studies have reported cultural differences in both bone density loss and risk for fractures. For example, Asian women have a higher risk for osteoporosis than other ethnic groups. One study of Japanese and Americans suggested, however, that Japanese women experience fewer hip fractures. One explanation might be that many Japanese women are used to sitting with knees flexed and they stand up from a position near the floor, thus ensuring the development of strong hip muscles and balancing skills, which help prevent falling. Most studies have been done on women, but men in the same ethnic groups may also carry a parallel although lower risk. [See Table Ethnic Differences in Bone Density and Osteoporosis.]

Ethnic Differences in Bone Density and Osteoporosis
Women by Ethnic Group	Low Bone Density Incidence	Osteoporosis Incidence
Asian	65.1%	8.2%
Native Americans	58.9%	9.5%
Caucasian	50.5%	5.2%
Hispanic	55.5%	4.3%
African Americans	38%	4%
From a Report at 1998 joint meeting of the American Society for Bone and Mineral Research.

Factors Associated with Osteoporosis

Depression. One study found an association between major depression and low bone mineral density in women. More than a third of premenopausal women who suffered from major depression had low bone density comparable to that of postmenopausal women. One explanation for this association is that depressed women have higher levels of the stress hormone cortisol, which may contribute to bone density loss.

Premature Gray Hair. One study reported that men and women whose hair turns gray in their 20s or was half gray by 40 have an incidence of thin bones that is four times higher than those who go gray later. Smoking, which also contributes to thin bones, has been associated with premature gray hair and may help explain the connection.

Specific Risk Factors for Fracture in People with Low-Bone Density

The risk for fracture itself in people with low bone density is compounded by certain features. Having multiple risk factors for osteoporosis itself poses a higher risk for fractures. Additional factors that increase the risk for falls:

Poor physical function, importantly slow gait and reduced muscle strength.
Poor concentration.
Impaired vision.
Hazardous environment (such as the presence of throw rugs in the house).

HOW IS OSTEOPOROSIS DIAGNOSED?

Osteoporosis is diagnosed when bone density has decreased to the point where fractures will happen with mild stress, the so-called fracture threshold. This is determined by measuring bone density and comparing the results with the norm. It should be noted that low scores on bone density are not very accurate in determining fracture risk without consideration of other risk factors for fracture. [ See Box Determining Osteoporosis.]

Candidates for Bone Density Screening or Testing

Experts now recommend bone density tests for the following people:

All women over age 65.
Postmenopausal women with one or more risk factors for osteoporosis.
Any older adult who suffers a fracture should be tested for osteoporosis. Fracture in the elderly is a major indicator of osteoporosis. Nevertheless, studies suggest that only a minority of these patients are evaluated and treated for osteoporosis.
Women on prolonged hormone replacement therapy or considering drug therapy for osteoporosis.
Anyone who has taken corticosteroids for two months or more.
Some experts believe that women as young as 21 who have strong risk factors for osteoporosis (such as anorexia or absence of menstruation from over-exercising) should consider being tested.
People with diseases (including those that require steroids) that put them at risk for osteoporosis.

Whether perimenopausal women should be screened is unclear. (Perimenopause is the period that extends a few years before and after menopause, approximately ages 50 to 59.) Even among Caucasian women, the risk for one fracture over a five year period is one out of every 750 women screened. High-risk women, however, (eg, thin Caucasian smokers) should discuss this with their physician.

Measuring Bone Density

The most important step in diagnosing osteoporosis is measuring bone density. A number of approaches are available.

Dual-Energy X-Ray Absorptiometry (DEXA). Currently, the standard technique for determining bone density is dual-energy x-ray absorptiometry (DEXA). It is simple and painless and takes two to four minutes. DEXA measures bone density by detecting the extent to which bones absorb photons that are generated by very low-level x-rays. (Photons are atomic particles with no charge.) Bone density is usually measured at the hip (rather than spine or wrist), which appears to be the most predictive of hip fracture. Hip fractures are the most dangerous, particularly in women older than sixty.

Ultrasound. Ultrasound techniques measure bone density in the heels, fingers, and leg bones. In early studies, they have not been as precise as DEXA, but advanced ultrasound techniques, such as quantitative ultrasound (QUS) are promising for improving accuracy in predicting fractures. Ultrasound itself is less expensive than DEXA and uses no radiation.

Other Techniques. Simpler techniques that measure density in specific parts of the body may prove to be accurate measures of overall bone loss and potential risk for fracture and be less costly. As bone density appears to differ from site to site within the same person, however, particularly in people younger than 65, some researchers currently question the efficacy of these non-hip techniques.

Single-energy x-ray absorptiometry measures the forearm and heel.
Dental x-rays of bone may prove to be helpful.
Quantitative computed tomography (QCT) scans, a form of CT scans, can provide highly detailed information about spinal density. Whether QCT predicts fracture risk accurately is, however, unknown.

Laboratory Tests

Laboratory blood or urine tests for identifying certain markers of bone loss may prove to be useful in certain cases:

High levels of the chemicals deoxypyridonoline and C-telopeptide in the blood may indicate increased risk for hip fracture. These substances are produced when bone is broken down.
A urine test detecting a substance called N-telopeptide may indicate bone loss (although it is not associated with any risk for fracture).

WHAT LIFESTYLE CHANGES CAN HELP OSTEOPOROSIS?

Because osteoporosis affects such a considerable portion of the female population, total prevention may not be possible, particularly in high-risk groups, and once a woman goes through menopause and more rapid bone depletion occurs, the line between prevention and treatment blurs. It should be noted that, despite their lower risk for osteoporosis, men should also protect their bones with the same healthy lifestyle habits.

Exercise

Exercise is very important for slowing the progression of osteoporosis. Even moderate exercise (two to four hours a week) reduces the risk for fracture in older men and women. Everyone who is in good health should aim for more, however. Exercise should be regular and life-long. Before beginning any strenuous exercise program, older patients or those at risk or who have serious medical conditions should have a general physical examination. Specific exercises may be better than others depending on the age group:

Children should begin exercising before adolescence, since bone mass increases during puberty and reaches its peak between ages 20 and 30. In fact, one study suggests that exercise may help develop bone mass in teenagers more effectively than high calcium intake. Exercises involving high-intensity jumping may be particularly bone strengthening in young children.
Weight-bearing exercise applies tension to muscle and bone and, in young people, encourages the body to compensate for the added stress by increasing bone density by as much as 2% to 8% a year. In premenopausal women these exercises are very protective. (Young men need high-intensity exercises to increase bone mass.) Careful weight training is also very beneficial for elderly people, especially women. A recently designed successful program for older women employs weighted vests instead of traditional weights. In a 2001 study, after more than five years women on the program lost less than 1% of hip bone mass compared to 3.8% in women not on the program.
Although low-impact aerobic exercises such as swimming and bicycling do not increase bone density, they are excellent for cardiovascular fitness and should be part of a regular regimen. Regular brisk long walks also improve bone density and mobility and may even relieve osteoarthritic pain. Most older individuals should avoid high-impact aerobic exercises, such as step aerobics, which increase the risk for osteoporotic fractures. Older people, particularly women who engage in jumping exercises should do so under supervision. In general, they should jump about 4 to 5 inches in the air and land flat-footed.
Exercises specifically targeted to strengthen the back help prevent fractures later on in life and can be beneficial in improving posture and reducing kyphosis (hunchback), even in people with existing severe conditions.
Low impact exercises that improve balance and strength, particularly yoga and tai chi, have been found to decrease the risk of falling. In one study, tai chi reduced the risk by almost half.

Calcium Supplements

Supplements of calcium plus vitamin D may help maintain bone density and reduce the risk for a first fracture in both men and women. One study reported that calcium slowed bone loss in portions of the hips where fracture is most serious. Even people already taking medication to prevent osteoporosis should take calcium (and vitamin D) daily. The benefits do not last when people stop taking these supplements.

Appropriate Daily Doses. Evidence is unclear about the best dosage. In general the amount taken depends on age and risk factors:

In young people, calcium intake should be 800 mg/day for children ages three to eight and 1,300 mg/day for children and adolescents ages nine to 17.
The standard recommended dose for people over 50 is about 1,200 mg per day, but may be higher or lower depending on risk factors. Even doses of 1,000 mg may help preserve bone in many postmenopausal women without osteoporosis, including during winter months (when bone loss is greatest). In women who have already experienced osteoporosis-related fractures, however, 1,000 mg daily may not add any protective benefits without bone-building medication.
Some experts suggest that all pregnant women, adolescents, and those on corticosteroids take 1,000 to 1,300 mg of calcium every day.
Breast-feeding women should have 2,000 mg per day.

Because of potential side effects with high amounts of calcium, an upper limit of 2,500 mg is recommended.

Forms of Calcium Supplements. Calcium supplements exist in different compounds, such as calcium carbonate (Caltrate, Os-Cal, Tums), calcium citrate (Citracal), calcium gluconate, and calcium lactate. Although all of these provide calcium, they have different calcium concentrations, absorption capabilities, and other actions. Their value in preserving bones depending on may different factors:

Calcium Concentrations: 40% of calcium carbonate is actually calcium, whereas calcium citrate is 24% calcium, and calcium gluconate is only 9% calcium.
Calcium Absorption Capabilities. The calcium must also be absorbed from the stomach into the bloodstream. Calcium citrate is better absorbed than many other calcium compounds. It was reported to be the first calcium supplement to preserve bone density after menopause. (Calcium citrate also increases iron absorption; milk and other calcium compounds tend to reduce iron absorption.) One simple method for testing the absorbency of a particular brand of calcium tablet is to place it in a glass of white vinegar at full strength and check to be sure that it breaks up within 30 minutes. Taking large amounts of antacids can impair calcium absorption. Supplements should be taken after meals.

Side Effects. High doses (over 2,500 mg per day) of calcium supplements may increase the risk for kidney stones. (Because many commercial foods are now fortified with calcium, this upper limit may be easier to reach than people think.) Calcium may boost the effects of drugs used to treat osteoporosis.

Although not a specific side effect of calcium, there has been much public concern about reports of small amount of lead in calcium supplements. Although exposure to high levels of lead can cause health problems, the amount in such supplements is very small and experts believe they pose no hazard.

Vitamin D and Other Vitamins

Vitamin D. Vitamin D is necessary for the absorption of calcium in the stomach and gastrointestinal tract and is the essential companion to calcium in maintaining strong bones.

Vitamin D is manufactured in the skin using energy from the ultraviolet rays in sunlight. It can also be obtained from dietary supplements. As a person ages, vitamin D levels decline. They also fall during winters months and when people have inadequate sunlight. Pollution may also contribute to less sunlight and declining vitamin D levels.

Current adult guidelines recommend the following:

400 IU (10 mcg) for people between ages 50 and 60.
600 IU (15 mcg) for those over 70 who do not have sufficient exposure to sunlight.

Diet and sunlight supply most people's need for vitamin D. Supplements or prescription form of vitamin D may be needed for people who have poor exposure to sunlight. It should be stressed that high amounts of vitamin D can be toxic. No one should take supplements over 800 IU a day without a doctor's guidance.

A number of vitamin D derivative have been developed and are being studied for osteoporosis. Calcitriol (Calcijex, Rocaltrol), for example, is a prescription-form of vitamin D that can increase bone mass and decrease the rate of spinal fractures. However, calcitriol increases the risk for high blood calcium levels (hypercalcemia) and requires frequent monitoring. Others vitamin D analogues under investigation include doxercalciferol (Hectorol), 22-oxacalcitriol (Maxacalcitol), and alfacalcidol. It should be noted that some studies suggest that vitamin D agents can protect against osteoporosis only in combination with calcium and that they do not appear to be protective themselves.

Vitamin K. Studies suggest that vitamin K has properties that protect bone and prevent fracture. Vitamin K2 (menatetrenone), a form of vitamin K, is proving to prevent fractures in people with osteoporosis. Intestinal bacteria produce vitamin K, and the vitamin is found in leafy vegetables, so deficiencies are rare, although there is some evidence that people may not be consuming enough of this nutrient. Vitamin K affects blood clotting, and supplements are not recommended without specific physician instruction.

Vitamin B12. One study reported that in people with osteoporosis and pernicious anemia, taking vitamin B12 (which is used to treat the anemia) also increased bone density.

Vitamin C and E. There has been some positive association between vitamin C and E intake and bone density. For example, a 2001 study reported better bone health in women who were taking estrogen therapy as well as calcium and vitamin C. More evidence is needed, however, to prove any direct benefits.

Vitamin A. High amounts of dietary vitamin A reduces bone density and may even increase the risk for fracture in postmenopausal women. (A form of vitamin A, retinoic acid, has been found to stimulate bone break down.)

Dietary Recommendations

Calcium from Diet. The effect of dietary calcium on bones is unclear. In one well-publicized 2000 study of 78,000 nurses, those who drank one to two glasses of milk reported higher fractures than those who drank less. The study had limitations, however, and did not establish any causal effect. Most other studies have reported that diary products benefit the bones. One report even suggests that milk proteins actually slow bone break down. Until more is known people should be sure their diets have sufficient calcium. Dietary calcium is available from many good sources.

Milk and Dairy Products. The best source of calcium in the diet is from milk fortified with vitamin D. Four glasses of milk provide about 1,200 mg of calcium. Skim milk and non-fat dairy products are the best choices and provide the same calcium as dairy products with fat. Adolescents should drink about three 8-ounce glasses of low-fat milk daily. (Teenage girls who fear that milk is fattening can take comfort in a study reporting that girls who consumed lots of dairy products were no more likely to become overweight than their milk-shunning peers.) In fact drinking carbonated beverages, particularly cola, increases the risk for bone fractures.
Other Calcium-Rich Foods. Other calcium-rich foods include shrimp, canned salmon or sardines, black strap molasses, calcium-fortified tofu, and almonds. A number of commercial foods, including orange juice and some cereals, are now calcium fortified. Dark green vegetables (broccoli, kale, turnip greens) are rich in calcium but little of it is absorbed (kale is best).

Soy and Isoflavones. Soy products (not soy sauce, however), which are high in plant estrogens called isoflavones, are provoking interest. Studies are suggesting that isoflavones-rich soy products may actually improve bone health in women of all ages. Tofu prepared with calcium may be particularly beneficial. In such cases 3 ounces of tofu supply 60% of daily calcium requirements. Some experts recommend 25 to 45 milligrams of isoflavones a day. Many soy products, including milk and powdered supplements, now list amounts of isoflavones per serving. (To date, evidence suggests that supplements that contain only selected soy isoflavones do not provide the benefits of the whole protein.)

Mineral-Rich Fruits and Vegetables. Studies suggest that diets rich in fresh fruits and vegetables reduce elimination of calcium from the body and help preserve bones. At least part of their benefits are derived from the minerals they contain, particularly magnesium and potassium.

Potassium. Potassium may be very important for strong bones and may help counteract negative effects of high-protein diets. Potassium-rich fruits include bananas, oranges, prunes, and cantaloupes, and vegetables that contain potassium include carrots, spinach, celery, alfalfa, mushrooms, lima beans, potatoes, avocados and broccoli.
Magnesium. Some studies have observed that low levels of magnesium may contribute to thinning bones. A 1998 study suggested that magnesium supplements help suppress the cycle that leads to bone loss. Experts recommend 350 mg a day. It should be noted, however, that excessive magnesium may be harmful in people with diabetes or kidney disease. Foods rich in magnesium include dairy products, spinach, potatoes, beets, nuts, sole, and halibut.
Other Minerals. Phosphorous, boron, and zinc have also been associated with bone protection.

Protein. The role of protein in osteoporosis is not entirely clear. An important 2000 study confirmed earlier reports that adequate protein is important for bone health. Animal protein, which has been associated with bone loss in some studies, was not detrimental. Other studies have also reported thinner bones in people who were deficient in protein. The effect of protein on bone is complicated, however, and laboratory studies suggest that high protein intake may increase calcium loss. And indeed some studies have particularly reported higher bone loss associated with a high intake of protein, particularly when calcium or potassium intake was low. The bottom line may be that in order for protein to be protective, or even not harmful, individuals should also eat plenty of mineral-rich foods. [ See Calcium in Diet and Mineral-Rich Fruits and Vegetables.] In any case, the best sources of protein are fish and soy.

Fats. Although no one wants to be overweight, even a slight excess of fat helps protect bones. In fact, in one 2000 study, women who ate more fat in their diet were, on average, better able to absorb calcium than were women who had been put on a low-fat, high-fiber diet. Fats are best obtained from fish or monounsaturated oils, such as olive or canola oils. Saturated fats (found in animal products) should be avoided. Everyone should, of course, be aware of excess calories and not use this advice as an excuse to overeat. A balanced diet is always the best advice.

Alcohol. Alcohol has different effects on bones depending on how much is consumed. One 2000 study found that women older than 65 who drank one to two drinks (one to two ounces) of alcohol weekly had higher bone density than non-drinkers. Alcohol in moderate amounts may reduce parathyroid hormone and increase estrogen levels. Excessive drinking, however, has been associated with brittle bones.

Coffee and Caffeine. There has been some concern that caffeine consumption, particularly from coffee, may increase calcium levels in urine and reduce levels in the body. In one trial, consumption of lots of coffee, nine or more cups per day, was associated with an increased risk of hip fractures in women, but not in men. Nevertheless, a 2001 animal study reported that coffee consumption did not produce bone loss. And other studies suggest that when calcium intake is sufficient, coffee does not harm bones.

Limiting Sodium and Avoiding Junk Food. Reducing salt may be useful. High sodium intake interferes with calcium retention; the higher the level of sodium the more calcium the body needs to meet its daily requirements. Fast foods and commercial snacks, which are high in sodium, have been linked with weak bones. In one study, women who tended to eat health foods (fruits, vegetables, milk, and cereal) had higher bone density, while those who tended to eat mainly "junk" food (soda, pizza, salty snacks) had the very lowest bone mass.

Oral Contraceptives Before Menopause

Researchers have hoped that oral contraceptives (OCs) containing estrogen may help protect bones. Studies have been conflicting. One study reported that women who took oral contraceptives for more than two years had a 20% higher risk for bone fractures than women who did not take OCs. Few of the women were over 50, however, so the risks for bone loss in older women with a history of OC usage are unknown. A 2000 study found that women who took low-dose OCs during perimenopause increased their bone density compared to those who took no oral contraceptives. More research is needed.

Smoking

Everyone should quit smoking. The risk for osteoporosis from smoking appears to diminish after quitting.

Preventing Falls and Fractures

An important component in reducing the risk for fractures is preventing falls. Risk factors for falling include the following:

Slow walking.
Inability to walk in a straight line.
Certain medications (such as tranquilizers).
Low blood pressure when rising in the morning.
Poor vision.

Some recommendations for preventing falls or fractures from falls in elderly people include the following:

Exercise to maintain strength and balance if there are no conflicting medical conditions.
Do not use throw or loose rugs on the floors.
Move any obstructions to walking, such as loose cords or very low pieces of furniture, away from traveled areas.
Rooms should be well lit.
Have regular eye check-ups.
Wear hip pads. Hip pads are specially designed to protect hipbones against falls and are worn under clothing. Studies are reporting that they can reduce the risk of hip fractures by nearly 85% if people are wearing them when they fall. The biggest problem with hip protectors is that many patients do not wear them.
Wear thinner, hard-soled shoes. Studies indicate these shoes are just as comfortable as the popular resilient-soled footwear, but they may be difficult to find. Soft-soled high-resilient so-called athletic footwear may contribute to impaired balance and dangerous falls, in part, because these cushioned shoes offer less stability.

WHAT ARE THE MEDICATIONS FOR OSTEOPOROSIS?

General Guidelines

Major drug therapies now exist for treating osteoporosis. Many of these drugs also have other advantages and disadvantages for postmenopausal women. [ See Table Bone-Protective Drugs with Other Health Effects after Menopause.]

Antiresorptive Agents. Most drugs currently used for osteoporosis are antiresorptives; that is, they slow the rate of bone remodeling but cannot rebuild bone. Such agents include bisphosphonates, hormone replacement therapy, SERMS, and calcitonin.
Anabolic, or Bone-Forming, Agents. Agents that rebuild bone are known as anabolics. Fluoride is one of the few bone-building agents, but it has limitations. Injections of parathyroid hormone increase bone mass and are proving to be very effective.

These agents may have side effects, and because osteoporosis has no symptoms, their benefits may not be apparent to patients. Many people, therefore, quit taking their medication. No one should discontinue treatment if their medication is preserving bone density and there are no severe side effects. It should be noted that some women taking these agents actually lose bone density the first year. Of interest in this regard was a 2000 study reporting that the women who lost the most bone during the first year of treatment experienced the greatest gains during subsequent years. Researchers recommend continuing treatment after the first year, even if a bone mass density (BMD) test is unpromising.

BisphosphonatesThe bisphosphonates inhibit osteoclast activity, increase bone mass, and are among the primary drugs against osteoporosis in postmenopausal women and in people taking corticosteroids or hormonal agents that suppress estrogen. They are proving to reduce the risk of both spinal and hip fractures, including in women who have had prior bone breaks.

Brands. A number of bisphosphonates in different forms are available or under investigation.

Alendronate (Fosamax) and risedronate (Actonel) are the standard oral bisphosphonates. Studies on both these agents are very favorable and report a reduction in spinal and hip fracture in people with osteoporosis. They also prevent osteoporosis in people taking corticosteroids. Both are taken orally. Both can be taken daily and alendronate is now available as a weekly dose. (In fact, a 2001 study found that a the high weekly dose appears to have the same effects on bones as daily dosing.)
Injected bisphosphonates are pamidronate (Aredia) and ibandronate. A 2001 study found that pamidronate prevents bone loss in the hip and lumbar spine in men receiving androgen-deprivation therapy for prostate cancer. Ibandronate is available in an injectable form and can be administered every three months. Although quarterly administration of ibandronate would greatly improve patient tolerance, studies to date do not show much protection against fractures with this agent.
An older bisphosphonate, etidronate (Didronel) can prevent early bone loss in menopausal women, help prevent fractures, and protect against bone loss in patients receiving high doses of corticosteroids. Some studies have not found it as effective as alendronate, however.
Investigative bisphosphonates include clodronate and tiludronate. A 2001 study of clodronate reported that it prevented bone loss in patients with osteoporosis and helped prevent fractures.

Candidates. National Osteoporosis Foundation's guidelines recommend that the following people should take or consider bisphosphonates:

Women with a below-normal bone density of 2.5 SD or greater and who have no history of fractures should take bisphosphonates.
Women with below-normal bone density 1 SD or more and have a history of fractures should consider bisphosphonates.

Alendronate has also now been approved for men with osteoporosis. Both alendronate and risedronate are approved for both men and women who take corticosteroids.

Side Effects. The most distressing side effects are gastrointestinal problems, particularly stomach cramps and heartburn, which are very common, occurring in nearly half of patients. Patients should strictly adhere to instructions for taking the drug (although gastrointestinal problems may still occur).

It is generally recommended that alendronate and risedronate be taken on an empty stomach in the morning with 6 to 8 ounces of water (not juice or carbonated or mineral water).
The patient should remain upright and not eat for 30 minutes after taking the pill.
Anyone taking the drug who develops chest pain, heartburn, or difficulty swallowing should stop taking the drug and see the physician. (It should be noted, however, that patients who stop taking the drug because of GI symptoms may be able to safely resume taking a bisphosphonate.)

Some physicians are concerned about the possibility for long-term injury to the gastrointestinal tract from bisphosphonates. In one 2000 study, risedronate was linked with a far lower number of gastrointestinal ulcers (4.1%) than was alendronate (13.2%). The study, however, and others have reported no higher than average risk for serious ulcers, such as bleeding ulcers even in those taking alendronate. In fact, one study reported that it was safe and effective in patients with Crohn's disease, an inflammatory bowel disease that increases the risk for osteoporosis.) Another study suggested that alendronate may not even add to the risk of stomach problems in people who are also taking nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, which are known to increase the risk for ulcers and bleeding. More research is needed to confirm the long-term safety of these agents, but recent evidence is reassuring.

Hormone Replacement Therapy

Hormone replacement therapy (HRT) contains estrogen with or without progesterone and is available in many brands and forms. HRT increases bone density. It also appears to improve balance and protects against falling. However, although studies report reductions in fractures, it is unclear whether HRT significantly reduces fractures in women over 60 years old. In any case, women who stop taking HRT begin to lose bone density, and after five years all protection is lost. It appears that estrogen must be taken life long for maximum protection against osteoporosis, which then increases the risk for breast cancer. Many experts now recommend other agents as first line therapies against osteoporosis. [For more information, see Report #40, Menopause, Estrogen Loss, and Their Treatments. ]

Candidates. HRT is important for premenopausal women who have had a hysterectomy that involved removal of both ovaries and uterus. HRT is also useful for reducing menopausal symptoms and may provide protection against fractures, at least in women younger than 60. Estrogen therapy has been investigated for young anorexic women, but studies have not reported any benefits. Studies have indicated that even low doses of estrogen increase bone density.

Side Effects and Complications. In spite of early reports of significant benefits, there are now many questions about long-term use of hormone therapies. Low doses would pose fewer health risks than standard higher-dose regimens and appear to reduce bone breakdown. It is not yet known, however, whether improvements will translate into lower fracture rates. [ See Table Bone-Protective Drugs with Other Health Effects after Menopause, above.]

In spite of estrogen's positive effects on cholesterol levels, recent studies are not finding HRT protective in women at risk for heart disease. Of note, in July 2001, the American Heart Association sent out an advisory regarding the use of HRT in postmenopausal women. These guidelines state that women with previous heart disease and those who have heart attacks while on HRT should stop the therapy. In addition, they recommend that doctors stop telling women that hormone replacement therapy has any cardiovascular benefits. Whether HRT prevents heart disease at all is the subject of two ongoing large trials. Data from these trials are expected within the next five years.
Studies are indicating some risk for breast cancer with long-term estrogen use. Hormone therapy that uses only estrogen increases the risk of uterine cancer; the addition of progesterone to the regimen significantly reduces this danger.
Hormone therapy with or without progesterone increases the risk for blood clots.

SERMs and Other Designer Hormones

A number of drugs known as selective estrogen-receptor modulator (SERM) have been designed with the goal of producing the same benefits that estrogen has on the bones and cholesterol levels without increasing the risk for hormone-related cancers. Some studies have been performed with SERMs in men, but benefits to date are not strong. More studies are needed.

Brands.

Raloxifene (Evista). Raloxifene (Evista) is the first SERM to be approved for preventing spinal fractures. (It does not appear to have any protective effect on other fractures, including those in the hip.) According to a 1999 study, raloxifene reduced the risk of invasive breast cancer by 76% during three years of treatment among postmenopausal women with osteoporosis. Longer studies are needed. Raloxifene does not effect ovulation and may be an option for women at risk for osteoporosis who are still menstruating, but it should not be used in pregnant or breastfeeding women. Raloxifene also increases risk for deep vein thrombosis, in which clots form in the large veins of the legs. Such clots can travel to the lungs, causing an embolism that may lead to complications, including death.
Tamoxifen (Nolvadex). Tamoxifen (Nolvadex) is the best-studied SERM. Low-dose tamoxifen may reduce the risk for fractures, but it has not been approved for this purpose. Tamoxifen has some beneficial effects on cholesterol levels (although not as strong as estrogen's) and does not increase the risk of uterine or breast cancer, as estrogen does. Taking tamoxifen for five years may lower breast cancer risk, at least in high-risk women, although protective benefits after that appear to be weak. Tamoxifen, like estrogen, however, increases the risk for uterine cancer and blood clots.
Tibolone (Livial). Tibolone (Livial) is showing promise in improving bone mineral density, most effectively in the lower spine. It has minimal side effects and patient compliance in clinical trials has been high.
Lasofoxifene. Early studies on lasofoxifene, an investigative SERM, are promising and reporting increased bone density and improvement in cholesterol levels.

Common Side Effects. Most SERMs do not relieve menopausal symptoms, and some exacerbate them. It should be noted that any beneficial effects of the SERMs on the heart (as with estrogen) are still unclear. Long term studies are also still needed to confirm or refute any effect on breast cancer for any of these agents. Because of the common risks for blood clots, anyone taking these agents should stop three days before any prolonged immobilization, such as long air flights or surgery.

Calcitonin

Produced by the thyroid gland, natural calcitonin regulates calcium levels by inhibiting the osteoclastic activity, the breakdown of bone. The drug version is derived from salmon and is available as a nasal spray (Miacalcin) and in injected form (Calcimar). Calcitonin is not used to prevent osteoporosis; it is used to treat osteoporosis. It may be effective for spinal protection (but not hip) in both men and women. Calcitonin may be an alternative for patients who cannot take alendronate or estrogen.

Calcitonin has been shown to slow bone loss progression and reduce spinal fractures, but some doctors question the design and methodology of important recent studies on the drug, particularly one in which the drop-out rate was 60%. Its effect on the hip is not known. It may also help relieve bone pain associated with established osteoporosis.

Side Effects. Side effects include headache, dizziness, anorexia, diarrhea, skin rashes, and edema (swelling). The most common adverse effect experienced with the injection is nausea, with or without vomiting; this occurs less often with the nasal spray. The nasal spray may cause nose bleeds, sinusitis, and inflammation of the membranes in the nose. Also, because calcitonin is a protein, a large number of people taking the drug develop resistance or allergic reactions after long-term use.

Parathyroid Hormone

Low-Dose Parathyroid Injections. Although high persistent levels of parathyroid hormone can cause osteoporosis, daily injections of low and intermittent doses of this hormone actually stimulates bone production. Unlike most treatments for osteoporosis, including bisphosphonates, the benefits may persist even after the injections have been stopped. Teriparatide (Forteo), an agent made from selected amino acids found in parathyroid hormone, has now been approved for treatment of osteoporosis in postmenopausal women. Studies suggest it significantly lowers the risk of fracture and increases bone mineral density. In one small study, parathyroid significantly reduced spinal fractures compared to hormone replacement therapy. Although not yet approved for men with osteoporosis, it may be effective for these patients as well.

Although the treatment requires injections, experts believe that patients will get used to them, just as people with diabetes grow accustomed to insulin shots. No significant side effects in humans have been reported to date, although early studies showed that long-term parathyroid use caused bone tumors in lab mice. Such effects have not been observed in humans to date. (Of note in this regard, persons with Paget disease, a disorder in which bone thickens but also, oddly, weakens, should not partake in clinical trials of parathyroid hormone, since they are at higher than normal risk for bone tumors.)

Parathyroid Suppression in People with Hyperparathyroidism. Individuals with acute hyperparathyroidism (excessive parathyroid hormone) tend to have marked osteoporosis. In one study, they experienced significant improvement in bone mineral density after undergoing a parathyroidectomy (removal of the parathyroid gland).

Fluoride

Fluoride contributes to rebuilding bone. Early studies had suggested that fluoride (along with calcium) might reduce risk of spinal fractures, but a more recent meta-analysis found that fluoride had little effect on bone growth. An interesting study on drinking water reported that either very low or very high levels (over 4.32 parts per million) was as associated with a higher risk for fractures while levels of about 1 per million was associated with a lower risk. A pilot study of intermittent etidronate/fluoride therapy found significant additive effects on bone mineral density.

Other Investigative Medications

All of the following are drugs under investigation for osteoporosis:

Osteoprotegerin. Osteoprotegerin is a unique agent that prevents bone break-down by regulating osteoclasts. It currently under investigation and showing promise in early trials. It may also be useful in conjunction with PTH, parathyroid hormone.
Statins. Statins are important agents used for lowering cholesterol, which have other heart protective properties as well. They include lovastatin (Mevacor), simvastatin (Zocor), pravastatin (Pravachol), and others. Some studies have reported a lower risk of hip and other fractures in people who take statins, although a 2001 study did not confirm any significant benefits. Few clinical trials have been published, to date, and more work is needed to confirm early studies.
Testosterone for Men with Osteoporosis. There is some evidence that testosterone replacement therapy may be helpful for men with osteoporosis. However more studies are needed to confirm this. Its efficacy is unproven in major clinical trials.
Strontium. Strontium, a chemical element found in bone, may help to increase bone formation and decrease bone resorption.

WHAT ARE THE TREATMENTS FOR FRACTURES?

Reconstructive Surgery

Reconstructive surgery is usually used for hip fractures and should be performed within 48 hours, assuming the patient has no other complicating medical conditions. After surgery, the patient should be mobilized within the first day. In one study, protein supplements helped people with hip fractures recover more quickly and reduced bone loss.

Percutaneous Vertebroplasty and Variants

Anecdotal reports indicate that the surgical procedures discussed in this section lessen pain, but there have been few controlled trials comparing surgical patient response to that of patients who are treated non-surgically.

Percutaneous Vertebroplasty. Researchers are testing a procedure to treat spinal fractures called percutaneous vertebroplasty, which employs an epoxy cement injected into fractured vertebrae. The epoxy becomes rock-hard within minutes, yet is light and supportive. The procedure uses a local anesthetic and the patient is able to walk around within a day. The vertebrae must be treated soon after the fracture and before it is has completely collapsed.

It is appropriate only in a minority of patients. Patients with herniated disks, degenerative disk disorder, or other problems involving spinal cord compression are not candidates for this procedure.

The most common severe complication is nerve root pain, most often caused when the cement leaks into spaces between the vertebrae. (Injectable bone-mineral substitutes that are similar to normal bone are being tested and may obtain better results than synthetic