Osteoporosis is often called the "silent disease" because it develops without symptoms. People often don't realize they have it until they break a bone. It's important to find out about the strength of your bones before they break so you can plan ways to decrease bone loss.

The only way to find out if you have osteoporosis is to have your bone density tested. Normal x-rays don't measure the density of bone. Bone density testing measures the amount of mineral in the bone. The bone density test compare your bone density to what is expected in someone of your age, sex and size. It also compares your bone density to the optimal peak bone density of a health young adult of the same sex. Several types of tests are available and all of them are painless, non-invasive, and involve very low radiation exposure. However, not all bone density screening techniques provide a consistent, accurate diagnosis of osteoporosis.

The best and most common bone density test is a dual energy x-ray absorptiometry, or DEXA, scan of the spine and hip, where fractures are most common and most debilitating. The test is a simple, painless procedure in which a person lies relaxed on a table and an arm of the scanning machine moves above the body. Each scan takes about 5 to 10 minutes.

Other tests are also commonly used. Peripheral dual energy absorptiometry, or PDXA, measures bone density in the wrist and forearm. Radiographic absorptiometry, or RA, uses a special hand x-ray to measure bone density of the hand. Quantitative computed tomography, or QCT, usually measures bone density in the spine. This method uses a slightly higher dose of radiation and is often more costly than DEXA.

A new testing method, recently approved by the U.S. Food and Drug Administration, is ultrasound testing, which estimates bone strength using sound waves transmitted through the patient's heel for about 10 seconds. Results compare well with bone density measurements by DEXA.

The 1998 National Osteoporosis Foundation Guidelines state that bone density testing should be done on all women over the age of 65, all postmenopausal women under age 65 who have one or more additional risk factors, postmenopausal women who have had fractures, women who are considering therapy for osteoporosis, and women who have been on hormone replacement therapy for prolonged periods.

As of July 1998, Medicare covers all FDA approved bone density technologies for the following five groups of qualified individuals: estrogen-deficent women at clinical risk for osteoporosis; individuals with vertebral abnormalities; individuals receiving, or planning to receive, long-term glucocorticoid (steriod) therapy; individuals with primary hyperparathyroidism; and individuals being monitored to assess the response or efficacy of an approved osteoporosis drug therapy. Medicare will only reimburse for bone densitometry tests when they are ordered by the treating health care provider. In addition, the frequency of testing is once every two years.

If you believe you are among these groups, you may want to ask your doctor about bone density testing. If you are not in these groups, you might still be eligible for testing. Check with your health care provider. It is ideal to get testing done before menopause to assess your bone density prior to bone loss due to a lack of estrogen.

Screening Resources

RadiologyInfo is the public information Web site developed and funded by the American College of Radiology (ACR) and the Radiological Society of North America (RSNA). - http://www.radiologyinfo.org/content/dexa.htm

International Society for Clinical Densitometry - http://www.iscd.org/

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