Osteoporosis causes the bones to become weak and break easily. In most cases, the disease does not cause symptoms. You may not know you have it until you fall and break a bone. Osteoporosis can be treated, and if it is found early, fractures can often be prevented.

To decide if you need testing for osteoporosis, your doctor will do a physical exam and ask questions about your medical history and lifestyle to assess your risk. You may also have x-rays to look for previous fractures and lab tests to rule out other bone problems. Your doctor may send you for bone mineral density testing if your results show you are at risk for osteoporosis.

Risk factors for osteoporosis
Assessing your risk factors will help your doctor decide if you need bone density testing. Risk factors are things that increase the chance of having a disease. The most important risk factors for osteoporosis are:

• Being a woman. In general, women are at much greater risk than men. About eight out of 10 people with osteoporosis are women.
• Advanced age. The risk of osteoporosis rises sharply after menopause due to the drop in estrogen, and the risk keeps rising with age.

Other factors that may put you at risk for osteoporosis include:

• Being thin or small-boned
• White or Asian ancestry
• A history of broken bones (fractures)
• A family history of fracture due to osteoporosis
• Low lifelong exposure to estrogen due to early menopause, having the ovaries removed or frequent missed periods
• Low levels of physical activity
• Smoking
• Excessive use of alcohol or caffeine
• Low calcium or vitamin D intake
• Use of medications that weaken the bones, such as long-term steroid medications
• Having a condition that can affect the bones, such as rheumatoid arthritis, an eating disorder or inflammatory bowel disease

Bone mineral density testing
Bone mineral density (BMD) testing is a way to check your bone health. A doctor will use a bone density test to diagnose osteoporosis, predict how likely you are to break a bone in the future and decide if you need treatment. The test can be repeated to see how well you respond to treatment.

Dual-energy x-ray absorptiometry (DEXA) is the best and most common bone density test. It is similar to an x-ray but it exposes you to a much smaller amount of radiation. It usually takes measurements of the lumbar spine and the hip. DEXA is quick, inexpensive and very accurate. A DEXA measurement of the hip bone (femoral neck) is the best predictor of future hip fractures.

Bone density measurements of the spine, heel, wrist, hand or forearm may be taken using other tests, such as:

• Peripheral dual-energy x-ray absorptiometry (pDEXA)
• Quantitative CT scan (QCT)
• Quantitative ultrasound (QUS)

A bone mineral density test gives results as number values (T-score and Z-score). The T-score compares your bone density to that of a healthy young adult of your sex. This score is the one used to diagnose osteoporosis. A T-score of minus 1 to minus 2.5 means low bone mass (osteopenia). A T-score of minus 2.5 or greater is osteoporosis. The higher the negative number, the greater your risk of fracture.

Who should be tested?
To decide who should be tested, many doctors rely on guidelines from the U.S. Preventive Services Task Force (USPSTF). These are considered the "gold standard" because they are based on careful reviews of the research. The USPSTF recommends that:

• Women age 65 and older should have routine screening for osteoporosis.
• Women should start routine screening at age 60 if they have factors that raise their risk of bone loss. A low body weight is the single best predictor of low bone density.

Testing may be warranted for younger women who are in menopause or older men if they have serious risk factors. Discuss your risks with your doctor. He or she can advise you when to start testing and how often it should be repeated.

Whether you are ready for testing or not, you can take steps to lower your risk of fractures. This includes not smoking, getting regular weight-bearing exercise with your doctor's approval, getting enough calcium and vitamin D, and limiting alcohol and caffeine.

Related Articles Bone Mineral Density Preventing Falls in the Elderly Risk Factors for Osteoporosis What Is Osteoporosis? Treatment of Osteoporosis

External Sources North American Menopause Society. Management of osteoporosis in postmenopausal women: 2006 position statement of the North American Menopause Society. Menopause. 2006;13(3):340-367. . Accessed September 08, 2009 U.S. Preventive Services Task Force. Screening for osteoporosis in postmenopausal women. . Accessed September 08, 2009 National Osteoporosis Foundation. Fast facts on osteoporosis.. Accessed September 08, 2009 National Osteoporosis Foundation. Clinician's guide to prevention and treatment of osteoporosis 2008. . Accessed September 08, 2009

This article was reviewed and updated 08-01-2009.