Osteoporosis is a silent disease. A decrease in height or a stooped posture (dowager's hump) may be the only signs. Often, osteoporosis is not suspected until you fall and break a bone. X-rays can reveal fractures and areas of weakened bone. It's best to get a bone mineral density (BMD) test early. This may help you prevent further bone loss.

What is a bone mineral density test?
A BMD test is used to detect osteoporosis. It can also predict the risk of future fractures and show how well treatment is working. It can spot osteoporosis in its earliest stages, before you've had any fractures. At this stage, it can still be treated.

The BMD is painless and safe. You can have the test as an outpatient and it takes only a few minutes. The test uses x-ray, so don't have it if you're pregnant.

Several types of machines can measure BMD. The most common is called DXA. DXA measures the spine, hip or total body. BMD measurements are usually taken of the spine and either the hip or wrist. Your reading is compared to someone of the same age, sex and size. If the test shows a normal density, you are at low risk for a bone fracture. The lower the density, the greater the risk for fracture.

Who should get a bone mineral density test?

• All women over age 65, regardless of risks
• Men over age 75
• Younger people with these risks:
• History of a fracture
• Low body weight
• Early menopause
• Those with long-term use of glucocorticoid medication or antacids containing aluminum hydroxide
• Anyone with a history of hyperparathyroidism
• Men with low testosterone levels

Diagnosis
The BMD is not the only step in detecting osteoporosis. Your medical background, your physical examination and other tests are also used to make a diagnosis.

• Medical interview. Your doctor will ask you questions to see if you're at risk for osteoporosis. Past falls, your diet, your family history and your medications are all important.
• Physical exam. Your doctor will check your height and look at your posture. Curvature of your upper and mid-back is caused by fractures of the bones in your spine. This may be from osteoporosis.
• X-rays. X-rays that detect a bone fracture in the past may also show areas of bone thinning. This is a sign of osteoporosis. The BMD gives information about your future risk for fractures. A quantitative CT scan (QCT) is another type of BMD test. It may be done if a DXA scan is inconclusive. Someone with scoliosis (sideways curvature of the spine) or osteoarthritis of the back may need a QCT.
• Lab tests. Lab tests can show when bone is breaking down faster than it is building up.

Your next steps
Talk to your doctor. You should be monitored and have repeat bone density testing to see if treatment is working. Medicare covers repeat BMD testing every two years.

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External Sources The National Osteoporosis Foundation. Bone density. Accessed January 20, 2006. The National Institutes of Health. Osteoporosis: the diagnosis. Accessed January 20, 2006. The American Association of Retired Persons. Boning up on osteoporosis. Accessed January 20, 2006. Massachusetts General Hospital. Screening for osteoporosis. Accessed January 20, 2006.