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.
Researchers estimate that about 1 out of 5 American women over the age of 50 have osteoporosis. About half of all women over the age of 50 will have a fracture of the hip, wrist, or vertebra (bones of the spine).
Osteoporosis occurs when the body fails to form enough new bone, 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, your body uses these minerals to produce bones. If you do not get enough calcium, or if your body does not absorb enough calcium from the diet, bone production and bone tissues may suffer.
As you age, calcium and phosphate may be reabsorbed back into the body from the bones, which makes the bone tissue weaker. This can result in brittle, fragile bones that are more prone to fractures, even without injury.
Usually, the loss occurs gradually over years. Many times, a person will have a fracture before becoming aware that the disease is present. By the time a fracture occurs, the disease is in its advanced stages and damage is severe.
The leading causes of osteoporosis are a drop in estrogen in women at the time of menopause and a drop in testosterone in men. Women over age 50 and men over age 70 have a higher risk for osteoporosis.
Other causes include:
- Being confined to a bed
- Chronic rheumatoid arthritis, chronic kidney disease, eating disorders
- Taking corticosteroid medications (prednisone, methylprednisolone) every day for more than 3 months, or taking some antiseizure drugs
White women, especially those with a family history of osteoporosis, have a greater than average risk of developing osteoporosis. Other risk factors include:
- Absence of menstrual periods (amenorrhea) for long periods of time
- Drinking a large amount of alcohol
- Family history of osteoporosis
- History of hormone treatment for prostate cancer or breast cancer
- Low body weight
- Too little calcium in the diet
There are no symptoms in the early stages of the disease.
Symptoms occurring late in the disease include:
Signs and tests
Bone mineral density testing (specifically a densitometry or DEXA scan) measures how much bone you have. Your health care provider uses this test to predict your risk for bone fractures in the future. For information about when testing should be done, see bone density test.
A special type of spine CT that can show loss of bone mineral density, quantitative computed tomography (QCT), may be used in rare cases.
In severe cases, a spine or hip x-ray may show fracture or collapse of the spinal bones. However, simple x-rays of bones are not very accurate in predicting whether someone is likely to have osteoporosis.
You may need other blood and urine tests if your osteoporosis is thought to be due to a medical condition, rather than simply the usual bone loss seen with older age.
The goals of osteoporosis treatment are to:
- Control pain from the disease
- Slow down or stop bone loss
- Prevent bone fractures with medicines that strengthen bone
- Minimize the risk of falls that might cause fractures
There are several different treatments for osteoporosis, including lifestyle changes and a variety of medications.
Medications are used to strengthen bones when:
- Osteoporosis has been diagnosed by a bone density study.
- Osteopenia (thin bones, but not osteoporosis) has been diagnosed by a bone density study, if a bone fracture has occurred.
Bisphosphonates are the primary drugs used to both prevent and treat osteoporosis in postmenopausal women.
- Bisphosphonates taken by mouth include alendronate (Fosamax), ibandronate (Boniva), and risedronate (Actonel). Most are taken by mouth, usually once a week or once a month.
- Bisphosphonates given through a vein (intravenously) are taken less often.
Calcitonin is a medicine that slows the rate of bone loss and relieves bone pain. It comes as a nasal spray or injection. The main side effects are nasal irritation from the spray form and nausea from the injectable form.
Calcitonin appears to be less effective than bisphosphonates.
HORMONE REPLACEMENT THERAPY
Estrogens or hormone replacement therapy (HRT) is rarely used anymore to prevent osteoporosis and are not approved to treat a woman who has already been diagnosed with the condition.
Sometimes, if estrogen has helped a woman, and she cannot take other options for preventing or treating osteoporosis, the doctor may recommend that she continue using hormone therapy. If you are considering taking hormone therapy to prevent osteoporosis, discuss the risks with your doctor.
Teriparatide (Forteo) is approved for the treatment of postmenopausal women who have severe osteoporosis and are considered at high risk for fractures. The medicine is given through daily shots underneath the skin. You can give yourself the shots at home.
Raloxifene (Evista) is 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%. However, 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 needed.
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).
Regular exercise can reduce the likelihood of bone fractures in people with osteoporosis. Some of the recommended exercises include:
- Weight-bearing exercises -- walking, jogging, playing tennis, dancing
- Resistance exercises -- free weights, weight machines, stretch bands
- Balance exercises -- tai chi, yoga
- Riding a stationary bicycle
- Using rowing machines
Avoid any exercise that presents a risk of falling, or high-impact exercises that may cause fractures.
Get at least 1,200 milligrams per day of calcium and 800 - 1,000 international units of vitamin D3. Vitamin D helps your body absorb calcium.Your doctor may recommend a supplement to give you the calcium and vitamin D you need.
Follow a diet that provides the proper amount of calcium, vitamin D, and protein. While this will not completely stop bone loss, it will guarantee that a supply of the materials the body uses to form and maintain bones is available.
High-calcium foods include:
- Ice cream
- Leafy green vegetables, such as spinach and collard greens
- Low-fat milk
- Sardines (with the bones)
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.
It is critical to prevent falls. Avoid sedating medications and remove household hazards to reduce the risk of fractures. Make sure your vision is good. Other ways to prevent falling include:
- Avoiding walking alone on icy days
- Using bars in the bathtub, when needed
- Wearing well-fitting shoes
Your response to treatment can be monitored with a series of bone mineral density measurements taken every 1 - 2 years.
Women taking estrogen should have routine mammograms, pelvic exams, and Pap smears.
There are no surgeries 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 vertebrae from becoming fractured by strengthening the bones in your spinal column.
The procedure involves injecting a fast-hardening glue into the areas 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.)
Medications to treat osteoporosis can help prevent fractures, but vertebrae that have already collapsed cannot be reversed.
Some persons with osteoporosis become severely disabled as a result of weakened bones. Hip fractures leave about half of patients 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.
- Compression fractures of the spine
- Disability caused by severely weakened bones
- Hip and wrist fractures
- 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 wish to be screened for the condition.
Calcium is essential for building and maintaining healthy bone. Vitamin D is also needed because it helps your body absorb calcium. Following a healthy, well-balanced diet can help you get these and other important nutrients throughout life.
Other tips for prevention:
- Avoid drinking excess alcohol
- Don't smoke
- Get regular exercise
A number of medications are approved for the prevention of osteoporosis.
Cranney A, Papaioannou A, Zytaruk N, et al., Clinical Guidelines Committee of Osteoporosis Canada. Parathyroid hormone for the treatment of osteoporosis: a systematic review. CMAJ. 2006 4;175(1):52-59.
Gass M, Dawson-Hughes B. Preventing osteoporosis-related fractures: an overview. Am J Med. 2006;119:S3-S11.
Estrogen and progestogen use in postmenopausal women: July 2008 position statement of The North American Menopause Society. Menopause. 2008;15(4):584-602.
Management of osteoporosis in postmenopausal women: 2006 position statement of The North American Menopause Society. Menopause. 2006;13(3):340-367.
National Osteoporosis Foundation. Clinician's Guide to Prevention and Treatment of Osteoporosis. Accessed July 23, 2008. Available online at http://www.nof.org/professionals/Clinicians_Guide.htm
Reviewed By: A.D.A.M. Editorial Team: David Zieve, MD, MHA, Greg Juhn, MTPW, David R. Eltz. Previously reviewed by Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network (11/23/2009).