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Encyclopedia -> Disease -> O -> Osteoporosis Causes and Risks: Osteoporosis is the most common type of metabolic bone disease. There are currently an estimated 10 million Americans suffering from osteoporosis as well as another 18 million who have low bone mass. Osteoporosis occurs when the body fails to form enough new bone, or when too much old bone is reabsorbed by the body, or both. Calcium and phosphate are two minerals that are essential for normal bone formation. Throughout youth, the body uses these minerals to produce bones. If calcium intake is not sufficient, or if the body does not absorb enough calcium from the diet, bone production and bone tissues may suffer. As people age, calcium and phosphate may be reabsorbed back into the body from the bones, which makes the bone tissue weaker. Both situations can result in brittle, fragile bones that are subject to fractures, even in the absence of trauma. Usually, the loss occurs gradually over years. Many times, a person will sustain a fracture before becoming aware that the disease is present. By the time this occurs, the disease is in its advanced stages and damage is profound. While there are a number of causes of osteoporosis, hormone deficiencies (estrogen in women and androgen in men) are the leading cause. Women, especially over the age of 60, are the most frequent sufferers of the disease. This is due to the loss of ovarian function and subsequent reduction in estrogen production that occurs at the time of menopause. Other causes include corticosteroid excess (from Cushing’s syndrome or from prescribed exogenous steroids), hyperthyroidism, hyperparathyroidism, immobilization, bone malignancies, certain genetic disorders, and other miscellaneous problems such as low calcium in diet. Researchers estimate that about 23% of American women over the age of 50 have osteoporosis. In addition, 40% and 56% of them have osteopenia, which is abnormally low bone density that may eventually deteriorate into osteoporosis if not treated. From these figures, researchers estimate that 50% of women over the age of 50 will suffer a fracture of the hip, wrist or vertebra. The risk of fracture in men of the same age group is about 13%. In 1995, direct medical expenditures relating to osteoporotic fractures totaled $13.8 billion. Risk factors, in addition to menopause, include genetic and ethnic background. Women who are white, especially those with a family history of osteoporosis, have a greater risk of developing osteoporosis. In fact, it is estimated that one out of two white women will experience a fracture relating to osteoporosis at some point in her life. Smoking, eating disorders, low body weight (less than 127 lbs), low amount of calcium in the diet, heavy alcohol consumption, and use of certain medications such as steroids are also risk factors. Prevention: Throughout life, dietary intake of calcium is essential for bone formation and maintenance of healthy bone. Dietary Vitamin D, whichaids in the absorption of calcium, is also essential. Maintaining a healthy diet as recommended by the FDA, (which includes a sufficient amount of calcium, phosphorous, and vitamin D), is very important. Regular exercise can reduce the likelihood of bone fractures. Studies show that exercises requiring muscles to pull on bones cause the bones to retain and maybe even gain density. Post-menopausal women, especially those with reduced bone density, may consider intervention with estrogen replacement therapy. This may prevent bone loss or fracture in some people. There are a number of side effects, both good and bad, associated with estrogen replacement therapy and the option should be discussed thoroughly with a health care provider. A number of new medications for the prevention of osteoporosis, including raloxifene and alendronate, are currently available and FDA approved, as discussed below. Symptoms: There are no symptoms associated with the early disease. As such, osteoporosis is a silent risk factor for fracture. Symptoms occurring late in the disease:
Signs and Tests:
Treatment: Treatments for osteoporosis focus on slowing down or stopping the demineralization process, preventing bone fractures by minimizing the risk of falls, and controlling pain associated with the disease. MEDICATIONS: Estrogen can slow or stop bone loss and, if estrogen treatment begins at menopause, it can reduce the risk of hip fractures up to 50 percent. Therapy is most effective if started at menopause, as most bone loss occurs 3-6 years after the onset of menopause. Many post-menopausal women choose estrogen replacement therapy (ERT) because of its proven usefulness in slowing the progress of or preventing osteoporosis. In some cases, ERT alleviates some of the irritating symptoms of menopause. This method of therapy is fairly inexpensive compared to the newer medications for osteoporosis discussed below. If estrogen replacement therapy is discontinued, bone loss will resume. Maximal protection from osteoporosis may indeed require lifelong dosing. Studies show that women who take estrogen for at least seven years between the onset of menopause and the age of 75 have a 50 percent reduction in risk of fractures. However after age 75, the risk is about the same as for those who did not take estrogen at all. In the 75 years and older group, bone mass only differs by about two percent between women who have taken estrogen for 10 years and those who have never taken it. Some women hesitate to use estrogen supplements because of the numerous potential risks that have been associated with long-term use. Before beginning ERT, the benefits and consequences of the treatment should be weighed and discussed thoroughly with a health care provider. The decision to take estrogen for preservation of bone density is complicated by its effects on other diseases, including a relatively small increase in the risk of breast cancer. ERT has classically been thought to reduce the risk of coronary artery disease in post-menopausal women. Recent studies have brought controversy to this issue by providing evidence that women may have a higher incidence of coronary events during the first year on ERT. Calcitonin, marketed under the name Miacalcin, is a medication that slows the rate of bone loss and relieves bone pain. The drug may be administered either by a nasal spray or by injection. The main side effects of calcitonin are nasal iritation from the spray form and nausea from the injectable form. While Calcitonin has been demonstrated to increase bone mineral density and reduce the risk of fractures in controlled studies, it appears to be less effective than ERT or alendronate (discussed below). Along with the newer medications discussed below, it is significantly more expensive than ERT. Alendronate (Fosamax) is a relatively new drug approved by the FDA for both prevention and treatment of osteoporosis. This medication prevents existing bone from being reabsorbed. Studies show that the risk of spinal fractures in post-menopausal women who take alendronate is reduced by nearly 50 percent. The main side effect of alendronate therapy is gastrointestinal upset and irritation/inflammation of the esophagus. As alendronate is difficult to absorb, it is recommended that the medicine be taken on an empty stomach and that the patient remain upright for at least an hour. Sodium fluoride is a compound that may serve to increase bone formation, unlike other osteoporosis medications that prevent bone loss. Sodium fluoride causes side effects of gastrointestinal upset and joint pains and is not presently FDA approved for osteoporosis. A recent breakthrough in the prevention and treatment of osteoporosis is FDA approval for the medication raloxifene (Evista). Raloxifene is similar to the drug tamoxifen used to treat breast cancer. Both these compounds bind to estrogen receptors that are the molecules that normally bind estrogen. A 1999 study showed that raloxifene reduced risk of vertebral fractures almost 50%. Raloxifene may also have mild protective effects against heart disease and breast cancer though more studies are required. The most serious adverse effect of raloxifene is a very small increase in the incidence of blood clots in the leg veins (deep venous thrombosis) or in the lungs (pulmonary embolus). LIFESTYLE CHANGES: Regular exercise can reduce the likelihood of bone fractures associated with osteoporosis. Studies show that exercises requiring muscles to pull on bones, cause the bones to retain and perhaps even gain density. Researchers found that women who walk a mile a day have four to seven more years of bone in reserve than women who don’t. Some of the recommended exercises include:
IMPORTANT: Any exercise that presents a risk of falling should be avoided. Fall prevention is an essential component of any comprehensive osteoporosis treatment program. Measures such as making sure the patient’s vision is good and appropriately corrected, avoiding sedating medications, and removing household hazards can significantly reduce the risk of fracture. A diet that includes an adequate amount of calcium, vitamin D, and protein should be maintained. While this will not completely stop bone loss, it will guarantee that a supply of the materials the body uses for bone formation and maintenance is available. Supplemental calcium should be taken as needed to achieve recommended daily calcium dietary intake (1200 mg a day in all adult white females and 1500 mg a day if at increased risk for osteoporosis). Vitamin D aids in calcium absorption and 400-800 IU per day should be taken by all individuals with increased risk of calcium deficiency and osteoporosis. MONITORING: Women taking estrogen should have routine mammograms, pelvic exams, and Pap smears. Patient response to treatment can be monitored with serial bone mineral density measurements every 1-2 years, though such monitoring is controversial, expensive and not universally performed. In the future, use of less elaborate measurements of bone turnover such as the N-telopeptide (Osteomark) urine test discussed above) may become a standard means for following osteoporosis, though experience is presently limited. Prognosis: Progression of the disease can sometimes be slowed or stopped with treatment. Some people become severely disabled as a result of weakened bones. Hip fractures, which are frequently sustained by people with osteoporosis, leave about 50% of victims unable to walk independently. This is one of the major reasons people are admitted to nursing homes. Although osteoporosis is debilitating, it does not affect life expectancy. Complications:
Call for an appointment with your health care provider if you have symptoms of osteoporosis or if you are interested in testing available for diagnosis or early detection.
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