Osteoporosis [1]

Alternative names
Thin bones

Definition
Osteoporosis is the thinning of bone tissue and loss of bone density over time.

Causes, incidence, and risk factors

Osteoporosis is the most common type of bone disease. There are currently an estimated 10 million Americans suffering from osteoporosis, as well as another 18 million who have low bone mass, or osteopenia.

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 the damage is profound.

The leading causes are a drop in estrogen in women at the time of menopause, and a drop in testosterone in men. Women, especially those over the age of 50, get osteoporosis more often than men.

Other causes include corticosteroid excess from Cushing’s syndrome, Hyperthyroidism, hyperparathyroidism, being confined to a bed, and bone cancers.

Researchers estimate that about 20% of American women over the age of 50 have osteoporosis. In addition, another 30% of them have osteopenia, which is abnormally low bone density that may eventually deteriorate into osteoporosis, if not treated.

About half of all women over the age of 50 will suffer a fracture of the hip, wrist, or vertebra.

Women who are white, especially those with a family history of osteoporosis, have a greater risk of developing osteoporosis. Other risk factors include Smoking, Eating disorders, low body weight, low amount of calcium in the diet, heavy alcohol consumption, Early Menopause, absence of Menstrual Periods (amenorrhea), and use of certain medications, such as steroids and anticonvulsants.

Symptoms

There are no symptoms in the early stages of the disease.

Symptoms occurring late in the disease include:

     
  • Fractures of the vertebrae, wrists, or hips (usually the first indication)  
  • Low back pain  
  • Neck pain  
  • Bone pain or tenderness  
  • Loss of height over time  
  • Stooped posture

Signs and tests

     
  • Bone mineral density (BMD) testing - as performed in dual-energy x-ray absorptiometry (DEXA) - measures the demineralization of the bones. This has become the gold standard for evaluation for osteoporosis. BMD testing should be performed on all postmenopausal women with fractures, all women under 65 with an additional risk factor for osteoporosis (besides menopause), and all women 65 and over.  
  • A spine CT can show demineralization. Quantitative computed tomography (QCT) can evaluate bone density, but is less available and is more expensive than DEXA.  
  • A spine or hip x-ray may show fracture or vertebral collapse in severe cases.  
  • Measuring the amount of calcium in your urine can provide some evidence of increased bone turnover, but is of limited value. A number of newer tests to evaluate bone turnover are becoming available, including measurement of urinary N-telopeptide (Osteomark). In the future, these may enhance your physician’s ability to diagnose early osteoporosis.

Treatment

Treatments for osteoporosis focus on slowing down or stopping bone loss, preventing bone fractures by minimizing the risk of falls, and controlling pain associated with the disease.

There are several different kinds of drugs used to treat osteoporosis. They vary in their side effects, benefits, and costs.

BISPHOSPHONATES

Bisphosphonates are a type of drug used for both the prevention and treatment of osteoporosis in postmenopausal women. The two bisphosphonates currently approved for osteoporosis - alendronate (Fosamax) and risedronate (Actonel) - prevent existing bone loss and reduce the risk of spinal and hip fractures.

While side effects are generally mild, potential side effects include stomach upset and irritation of the esophagus. Because bisphosphonates are difficult to absorb, these medicines should be taken on an empty stomach. The patient should not lie down or consume food or beverages (other than water) for at least 30 minutes after taking the medicine. The physician may also recommend taking calcium and Vitamin D supplements.

Actonel is approved for use in men with osteoporosis. Both Actonel and Fosamax prevent and treat osteoporosis in men and women taking daily steroids for chronic conditions like Asthma and arthritis.

RALOXIFENE

Raloxifene (Evista) is another drug used for the prevention and treatment of osteoporosis. Raloxifene is similar to the Breast cancer drug tamoxifen. Raloxifene can reduce the risk of spinal fractures by almost 50%. (It does not appear to prevent other fractures, including those in the hip.) It may have protective effects against heart disease and Breast cancer, though more studies are required.

The most serious side effect of raloxifene is a very small risk of Blood clots in the leg veins (Deep venous thrombosis) or in the lungs (Pulmonary embolus).

HORMONE REPLACEMENT THERAPY

A woman’s body produces less estrogen during and after menopause, which may affect her bone strength. Based on early studies, many physicians used to believe that HRT might be beneficial for reducing the risk of heart disease and bone fractures caused by osteoporosis in addition to treating menopausal symptoms. The results of a new study, called the Women’s Health Initiative (WHI), has led physicians to revise their recommendations regarding HRT.

The WHI, started in 1993, enrolled 161,809 women between the ages of 50-79 in 40 different medical centers. Part of the study was intended to examine the health benefits and the risks of Hormone replacement therapy (HRT), including the risks of Breast cancer, Heart attacks, Strokes, and Blood clots.

In July 2002, one component of the WHI, which studied the use of estrogen and progestin in women who had a uterus, was stopped early because the health risks exceeded the health benefits. A second component of the study, which studied estrogen-only therapy in women who no longer have a uterus, was stopped early in March 2004.

The WHI study showed that women taking HRT had 34% fewer hip fractures and 24% fewer fractures than women not receiving hormones. However, the main reason for stopping the estrogen-progestin study was because of a 26% increase in Breast cancer in women taking HRT, as well as increases in Heart attacks, Strokes, and thromboembolic events (Blood clots).

Women who are considering taking HRT to prevent osteoporosis should discuss with their physician their individual risk of Coronary heart disease, Stroke, Blood clots, and Breast cancer.

CALCITONIN

Calcitonin, marketed under the names Miacalcin (nasal spray) and Calcimar (injectable), is a medication that slows the rate of bone loss and relieves bone pain. The main side effects of calcitonin are nasal irritation from the spray form, and nausea from the injectable form.

While calcitonin slows bone loss and reduces the risk of fractures, it appears to be less effective than ERT or biphosphonates. As with some of the other newer medications, it is significantly more expensive than ERT.

EXERCISE

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:

     
  • Weight-bearing exercises - walking, jogging, playing tennis, dancing  
  • Resistance exercises - free weights, weight machines, rubber stretch bands  
  • Balancing exercises - tai chi, yoga  
  • Riding stationary bicycles  
  • Using rowing machines  
  • Walking  
  • Jogging

Any exercise that presents a risk of falling should be avoided!

DIET

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. Current recommendations are for nonpregnant, menstruating women to consume 1000mg/day, pregnant women need 1200mg/day, and postmenopausal or nursing mothers should consume 1500 mg/day.

High-calcium foods include low-fat milk, yogurt, ice cream and cheese, tofu, salmon and sardines (with the bones), and leafy green vegetables, such as spinach and collard greens. 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.

STOP UNHEALTHY HABITS

Quit Smoking, if you smoke. Also limit alcohol intake. Too much alcohol can damage your bones, as well as put you at risk for falling and breaking a bone.

PREVENT FALLS

It is critical to prevent falls. Make sure your vision is good, avoid sedating medications, and remove household hazards to reduce the risk of fractures. Other ways to prevent falling include wearing good-fitting shoes, avoiding walking alone on icy days, and using bars in the bathtub, when needed.

MONITORING

Your response to treatment can be monitored with serial bone mineral density measurements every 1-2 years, though such monitoring is controversial and expensive. In the future, less elaborate measurements of bone turnover may become a standard means for following osteoporosis.

Women taking estrogen should have routine mammograms, pelvic exams, and Pap smears.

RELATED SURGERIES

There are no surgeries specifically for treating osteoporosis itself. However, a procedure called vertebroplasty can be used to treat any small fractures in your spinal column due to osteoporosis. It can also help prevent weak vertebra from becoming fractured by strengthening the bones in your spinal column. The procedure involves injecting a fast-hardening glue into the regions that are fractured or weak. A similar procedure, called kyphoplasty, uses balloons to widen the spaces that need the glue. (The balloons are removed during the procedure.)

Expectations (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

     
  • Compression fractures of the spine  
  • Hip fractures and wrist fractures  
  • Disability caused by severely weakened bones  
  • Loss of ability to walk, due to hip fractures

Calling your health care provider

Call your health care provider if you have symptoms of osteoporosis, or if you are interested in testing available for diagnosis or early detection.

Prevention

Calcium is essential for building and maintaining healthy bone. Vitamin D, which helps your body absorb calcium, is also essential. To get these and other important nutrients throughout life, make sure to keep an overall healthy, well-balanced diet.

To help prevent osteoporosis, don’t smoke, and avoid drinking excess alcohol.

Regular exercise can prevent bone fractures. Exercises where muscles pull on bones cause the bones to retain, and possibly gain, density.

A number of new medications for the prevention of osteoporosis, including raloxifene and alendronate, are currently available and FDA approved.

If you are a candidate for Hormone replacement therapy (HRT), discuss the risks and benefits thoroughly with your health care provider.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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