Osteoporosis is a condition characterized by the loss of the normal density of bone, resulting in fragile bone. Osteoporosis leads to literally abnormally porous bone that is more compressible like a sponge, than dense like a brick. This disorder of the skeleton weakens the bone causing an increase in the risk for breaking bones (bone fracture).
Normal bone is composed of protein, collagen, and calcium all of which give bone its strength. Bones that are affected by osteoporosis can break (fracture) with relatively minor injury that normally would not cause a bone fracture. The fracture can be either in the form of cracking (as in a hip fracture), or collapsing (as in a compression fracture of the vertebrae of the spine). The spine, hips, and wrists are common areas of bone fractures from osteoporosis, although osteoporosis-related fractures can also occur in almost any skeletal bone.
What are the symptoms of osteoporosis?
The osteoporosis condition can be present without any symptoms for decades, because osteoporosis doesn't cause symptoms unless bone fractures. Some osteoporosis fractures may escape detection until years later. Therefore, patients may not be aware of their osteoporosis until they suffer a painful fracture. Then the symptoms are related to the location of the fractures.
Fractures of the spine (vertebra) can cause severe "band-like" pain that radiates around from the back to the side of the body. Over the years, repeated spine fractures can cause chronic lower back pain as well as loss of height or curving of the spine, which gives the individual a hunched-back appearance of the upper back, often called a "dowager hump."
A fracture that occurs during the course of normal activity is called a minimal trauma fracture or stress fracture. For example, some patients with osteoporosis develop stress fractures of the feet while walking or stepping off a curb.
Hip fractures typically occur as a result of a fall. With osteoporosis, hip fractures can occur as a result of trivial accidents. Hip fractures may also be difficult to heal after surgical repair because of poor bone quality.
What are the consequences of osteoporosis?
Osteoporosis bone fractures are responsible for considerable pain, decreased quality of life, lost workdays, and disability. Up to 30% of patients suffering a hip fracture will require long term nursing home care. Elderly patients can further develop pneumonia and blood clots in the leg veins that can travel to the lungs (pulmonary embolism) due to prolonged bed rest after a hip fracture. Some 20% of women with a hip fracture will die in the subsequent year as an indirect result of the fracture. In addition, once a person has experienced a spine fracture due to osteoporosis, he or she is at very high risk of suffering another such fracture in the near future (next few years). About 20% of postmenopausal women who experience a vertebral fracture will suffer a new vertebral fracture of bone in the following year.
Why is osteoporosis an important public health issue?
* In the United States, 44 million people have low bone density (either osteoporosis or osteopenia, see below). This amounts to 55% of the U.S. population 50 years-old and over.
* In the U.S., more than 10 million people have osteoporosis and almost 34 million more have low bone density.
* One in two white women will experience a bone fracture due to osteoporosis in her lifetime.
* In the United States, direct health care costs from osteoporosis fractures amount to billion dollars, without even taking into account the indirect costs, such as lost work productivity.
* Twenty percent of those who experience a hip fracture will die in the year following the fracture.
* One-third of hip fracture patients are discharged to a nursing home within the year after fracture.
* Only one-third of hip fracture patients regain their pre-fracture level of function.
With the aging of America, the number of people with osteoporosis related fractures will increase exponentially. The pain, suffering, and economic costs will be enormous.
What factors determine bone strength?
Bone mass (bone density) is the amount of bone present in the skeletal structure. Generally, the higher the bone density is, the stronger are the bones. Bone density is greatly influenced by genetic factors, which in turn are sometimes modified by environmental factors and medications. For example, men have a higher bone density than women. African Americans have a higher bone density than Caucasian or Asian Americans.
Normally, bone density accumulates during childhood and reaches a peak by around age 25. Bone density is then maintained for about ten years. After age 35, both men and women will normally lose 0.3% to 0.5% of their bone density per year as part of the aging process.
Estrogen is important in maintaining bone density in women. When estrogen levels drop after menopause, bone loss accelerates. During the first five to ten years after menopause, women can suffer up to two to four percent loss of bone density per year! This can result in the loss of up to 25 to 30% of their bone density during that time period. Accelerated bone loss after menopause is a major cause of osteoporosis in women.
What are the risk factors for developing osteoporosis?
Factors that will increase the risk of developing osteoporosis are:
* Female gender;
* Caucasian or Asian race;
* Thin and small body frames;
* Family history of osteoporosis (for example, having a mother with an osteoporotic hip fracture doubles your risk of hip fracture);
* Personal history of fracture as an adult;
* Cigarette smoking;
* Excessive alcohol consumption;
* Lack of exercise;
* Diet low in calcium;
* Poor nutrition and poor general health;
* Malabsorption (nutrients are not properly absorbed from the gastrointestinal system) from conditions such as celiac sprue;
* Low estrogen levels (such as occur in menopause or with early surgical removal of both ovaries);
* Chemotherapy can cause early menopause due to its toxic effects on the ovaries;
* Amenorrhea (loss of the menstrual period) in young women also causes low estrogen and osteoporosis; Amenorrhea can occur in women who undergo extremely vigorous training and in women with very low body fat (example: anorexia nervosa);
* Chronic inflammation, due to diseases (such as rheumatoid arthritis and chronic liver diseases);
* Immobility, such as after a stroke, or from any condition that interferes with walking;
* Hyperthyroidism, a condition wherein too much thyroid hormone is produced by the thyroid gland (as in Grave's disease) or is caused by taking too much thyroid hormone medication;
* Hyperparathyroidism, a disease wherein there is excessive parathyroid hormone production by the parathyroid gland (a small gland located near the thyroid gland). Normally, the parathyroid hormone maintains blood calcium levels by, in part, removing calcium from the bone. In untreated hyperparathyroidism, excessive parathyroid hormone causes too much calcium to be removed from the bone, which can lead to osteoporosis;
* Vitamin D deficiency. Vitamin D helps the body absorb calcium. When vitamin D is lacking, the body cannot absorb adequate amounts of calcium to prevent osteoporosis. Vitamin D deficiency can result from lack of intestinal absorption of the vitamin such as occurs in celiac sprue and primary biliary cirrhosis;
* Certain medications can cause osteoporosis. These include long-term use of heparin (a blood thinner), anti-seizure medications phenytoin (Dilantin) and phenobarbital, and long term use of oral corticosteroids (such as Prednisone).
How is osteoporosis diagnosed?
A routine x-ray can reveal osteoporosis of the bone, which appears much thinner and lighter than normal bones. Unfortunately, by the time x-rays can detect osteoporosis, at least 30% of the bone has already been lost. In addition, x-rays are not accurate indicators of bone density. The appearance of the bone on x-ray is often affected by variations in the degree of exposure of the x-ray film.
The National Osteoporosis Foundation, the American Medical Association, and other major medical organizations are recommending a dual energy x-ray absorptiometry scan (DXA, formerly known as DEXA) for diagnosing osteoporosis. DXA measures bone density in the hip and the spine. The test takes only 5 to 15 minutes to perform, uses very little radiation (less than one tenth to one hundredth the amount used on a standard chest x-ray), and is quite precise.
The bone density of the patient is then compared to the average peak bone density of young adults of same sex and race. This score is called the "T score," and it expresses the bone density in terms of the number of standard deviations (SD) below peak young adult bone mass.
* Osteoporosis is defined as bone density T score of -2.5 SD or below.
* Osteopenia (between normal and osteoporosis) is defined as bone density T score between -1 and -2.5 SD.
Who should have bone density testing?
The National Osteoporosis Foundation guidelines state that there are several groups of people who should consider DXA testing:
* All postmenopausal women below age 65 who have risk factors for osteoporosis;
* All women aged 65 and older;
* Postmenopausal women with fractures, although this is not mandatory because treatment may well be started regardless of bone density;
* Women with medical conditions associated with osteoporosis. These diseases number more than 50. A primary care physician can scan a patient's list of medical illnesses to verify that one of these conditions is not present;
How is osteoporosis treated and prevented?
The goal of osteoporosis treatment is the prevention of bone fractures by stopping bone loss and by increasing bone density and strength. Although early detection and timely treatment of osteoporosis can substantially decrease the risk of future fracture, none of the available treatments for osteoporosis are complete cures. In other words, it is difficult to completely rebuild bone that has been weakened by osteoporosis. Therefore, prevention of osteoporosis is as important as treatment. Osteoporosis treatment and prevention measures are:
1. Life style changes including quitting cigarette smoking, curtailing alcohol intake, exercising regularly, and consuming a balanced diet with adequate calcium and vitamin D;
2. Medications that stop bone loss and increase bone strength, such as alendronate (Fosamax), risedronate (Actonel), raloxifene (Evista), ibandronate (Boniva), calcitonin (Calcimar), and zoledronate (Reclast);
3. Medications that increase bone formation such as teriparatide (Forteo).
Lifestyle changes
Exercise, quitting cigarettes, and curtailing alcohol
Exercise has a wide variety of beneficial health effects. However, exercise does not bring about substantial increases in bone density. The benefit of exercise for osteoporosis has mostly to do with decreasing the risk of falls, probably because balance is improved and/or muscle strength is increased. Research has not yet determined what type of exercise is best for osteoporosis or for how long. Until research has answered these questions, most doctors recommend weight-bearing exercise, such as walking, preferably daily.
A word of caution about exercise: it is important to avoid exercises that can injure already weakened bones. In patients over 40 and those with heart disease, obesity, diabetes mellitus, and high blood pressure, exercise should be prescribed and monitored by their doctors. Finally, extreme levels of exercise (such as marathon running) may not be healthy for the bones. Marathon running in young women that leads to weight loss and loss of menstrual periods can actually cause osteoporosis.
Smoking one pack of cigarettes per day throughout adult life can itself lead to loss of 5% to 10% of bone mass. Smoking cigarettes decreases estrogen levels and can lead to bone loss in women before menopause. Smoking cigarettes can also lead to earlier menopause. In postmenopausal women, smoking is linked with increased risk of osteoporosis. Data on the effect of regular consumption of alcohol and caffeine on osteoporosis is not as clear as with exercise and cigarettes. In fact, research regarding alcohol and caffeine as risk factors for osteoporosis shows widely varying results, and is controversial. Certainly, these effects are not as powerful as other factors. Nevertheless, moderation of both alcohol and caffeine is prudent.
Calcium Supplements
Building strong and healthy bones requires an adequate dietary intake of calcium and exercise beginning in childhood and adolescence for both sexes. Most importantly, however, a high dietary calcium intake or taking calcium supplements alone is not sufficient in treating osteoporosis, and should not be viewed as an alternative to or substituted for more potent prescription osteoporosis medications. In the first several years after menopause, rapid bone loss can occur even if calcium supplements are taken.
The following calcium intake has been recommended by The National Institutes of Health Consensus Conference on Osteoporosis for all people, with or without osteoporosis:
* 800 mg/day for children ages 1 to 10
* 1000 mg/day for men, premenopausal women, and postmenopausal women also taking estrogen
* 1200 mg/day for teenagers and young adults ages 11 to 24
* 1500 mg/day for post menopausal women not taking estrogen
* 1200mg to 1500 mg/day for pregnant and nursing mothers
* The total daily intake of calcium should not exceed 2000 mg
Daily calcium intake can be calculated by the following method:
1. Excluding dairy products, the average American diet contains approximately 250 mg of calcium;
2. There is approximately 300 mg of calcium in an 8-ounce glass of milk;
3. There is approximately 450 mg of calcium in 8 ounces of plain yogurt;
4. There is approximately 1300 mg of calcium in 1 cup of cottage cheese;
5. There is approximately 200 mg of calcium in 1 ounce of cheddar cheese;
6. There is approximately 90 mg of calcium in ½ cup of vanilla ice cream;
7. There is approximately 300 mg of calcium in 8 ounces of calcium-fortified orange juice.
Unfortunately, surveys have shown that average women in the United States are consuming less than 500 milligrams of calcium per day in their diet, less than the recommended amounts. Additional calcium can be obtained by drinking more milk and eating more yogurt or cottage cheese, or by taking calcium supplement tablets as well from calcium-fortified foods, such as orange juice.
The various calcium supplements contain different amounts of elemental calcium (the actual amount of calcium in the supplement). For example, Caltrate, Os-Cal and Tums are calcium carbonate salts. Each 1250 mg of calcium carbonate salt tablet (such as Caltrate 600 mg, Os-Cal 500 mg, or Tums 500 mg extra strength) contains 500 mg of elemental calcium. A person who needs 1000 mg/day of calcium supplement can take one tablet of Tums 500 mg extra strength (containing 500 mg of elemental calcium) twice daily with meals.
The calcium carbonate supplements are best taken in small divided doses with meals. The intestines may not be able to reliably absorb more than 500 mg of calcium all at once. Therefore, the best way to take 1000 mg of a calcium supplement is to divide it in two doses. Likewise, a dosage of 1500 mg should be divided into three doses.
Calcium supplements are safe and generally well tolerated. Side effects are indigestion and constipation. If constipation and indigestion occur with calcium carbonate supplements, calcium citrate (Citracal) can be used. Some patients have difficulty swallowing calcium tablets. In this situation, chewable candy-like calcium in the form of Viactiv brand is available. Certain medications can interfere with the absorption of calcium carbonate. Examples of such medications include proton-pump inhibitors [omeprazole (Prilosec), lansoprazole (Prevacid), lansoprazole (Protonix), and rabeprazole (Aciphex)], which are used in treating GERD (acid reflux) or peptic ulcers. In these cases, calcium citrate is preferred.
Many "natural" calcium carbonate preparations, such as oyster shells or bone meal, may contain high levels of lead or other harmful elements and should be avoided.
* Women whose decision to use medication might be aided by bone density testing.
The National Osteoporosis Foundation guidelines state that bone density testing does not need to be performed if a person has a known osteoporotic fracture because the condition will be treated with or without bone density results. In addition, bone density testing is not appropriate if the person undergoing the test is not willing to take any treatment based on the results. Therefore, if bone density testing is done, it should be performed on people willing to take some specific action based on the results.
Vitamin D
An adequate calcium intake and adequate body stores of vitamin D are important foundations for maintaining bone density and strength. However, vitamin D and calcium alone are not sufficient treatment for osteoporosis. They are given in conjunction with other treatments. Vitamin D is important in several respects:
- Vitamin D helps the absorption of calcium from the intestines.
- A lack of vitamin D causes calcium-depleted bone (osteomalacia), which further weakens the bones and increases the risk of fractures.
- Vitamin D, along with adequate calcium (1200 mg of elemental calcium), has been shown in some studies to increase bone density and decrease fractures in older postmenopausal, but not in premenopausal or perimenopausal women.
Vitamin D comes from the diet and the skin. Vitamin D production by the skin is dependent on exposure to sunlight. Active people living in sunny regions (Southern California, Hawaii, countries around the equator, etc.) can produce most of the vitamin D they need from their skin. Conversely, lack of exposure to sunlight, due to residence in northern latitudes or physical incapacitation, causes vitamin D deficiency. In less temperate regions such as Minnesota, Michigan, and New York, skin production of vitamin D is markedly diminished in the winter months, especially among the elderly. In that population, dietary vitamin D becomes important.
Unfortunately, vitamin D deficiency is quite common in the United States. In a study of hospitalized patients in a general medical ward, vitamin D deficiency was detected in 57% of the patients. An estimated 50% of elderly women consume far less vitamin D in their diet than is recommended.
The Food and Nutrition Board of the Institute of Medicine has recommended the following as an as adequate vitamin intake:
- 200 IU daily for men and women 19 to 50 years old,
- 400 IU daily for men and women 51 to 70 years old, and
- 600 IU daily for men and women 71 years and older.
But if a person already has osteoporosis, it is advisable to ensure 400 IU twice per day as usual daily intake, most commonly as a supplement alongside prescription osteoporosis medication.
An average multivitamin tablet contains 400 IU of vitamin D. Therefore, one to two multivitamins a day should provide the recommended amount of vitamin D. Alternatively, vitamin D can be obtained in combination with calcium in tablet forms, such as Caltrate 600 + D (600 mg of calcium and 200 IU of vitamin D) and others. Adequate calcium and vitamin D are critical for bone health.
Adequate levels of calcium and vitamin D are essential for optimal bone health, especially in addition to any prescription osteoporosis medication. Chronic excessive use of vitamin D, especially above 2000 units/day, can lead to toxic levels of vitamin D, elevated calcium levels in blood and urine, and may also cause kidney stones. Since various dietary supplements may also contain vitamin D, it is important to review vitamin D content in dietary supplements before taking additional vitamin D.
Hormone therapy (menopausal hormone therapy)
Menopausal hormone therapy (previously referred to as hormone replacement therapy or HRT) has been shown to prevent bone loss, increase bone density, and prevent bone fractures. It is useful in preventing osteoporosis in postmenopausal women. Estrogen is available orally (Premarin, Estrace, Estratest, and others) or as a skin patch (Estraderm, Vivelle, and others).
Estrogen is also available in combination with progesterone as pills and patches. Progesterone is routinely given along with estrogen to prevent uterine cancer that might result from estrogen use alone. Women who have had a hysterectomy (surgical removal of the uterus) may take estrogen alone. Nasally delivered estrogen and lower-dose combination pills of estrogen and progesterone are also being studied. However, due to adverse effects of menopausal hormone therapy, such as increased risks of heart attack, stroke, blood clots in the veins, and breast cancer; menopausal hormone therapy is no longer recommended for long-term use in the therapy of osteoporosis. Rather, menopausal hormone therapy is used short-term to relieve menopausal hot flashes.
Every woman needs to have an individualized discussion regarding estrogen replacement with her doctor because each woman will have a different balance of risk and benefit expected from hormone therapy. For more, please read the Hormone Therapy article.
