Doctors use bone density tests to determine if you are at risk for osteoporosis or other bone conditions. Osteoporosis causes bones to become porous and fragile, resulting in fractures. If the test reveals a problem, your doctor will prescribe medication to slow or halt your bone loss and rebuild bone.
Identification
A bone density test, also known as a DXA scan, uses X-rays to measure how many grams of calcium and other minerals are present in a bone segment, according to MayoClinic.com. Your doctor reviews your bone density scores to determine if you are likely to develop osteoporosis. A high mineral count indicates denser bones that are more resistant to breaking, while a lower count indicates that your bones are weak and fragile.
Reasons to Have the Test
Your doctor will review your risk factors to decide if you should undergo a bone density test. He may recommend a test if you are a woman who is past menopause, have a family history of osteoporosis, have a low body weight for your height or take medications known to cause bone loss, such as anti-seizure drugs or corticosteroids. A bone density scan may also be recommended for men with conditions affecting the bones, people with a history of multiple fractures or people who have thyroid, kidney or liver disease. MayoClinic.com reports that women of white or Southeast Asian descent have the greatest risk of developing osteoporosis.
Procedure
During a bone density test, you lie down on a padded table in a large machine called a central DXA machine. When the test begins, the imaging arm of the machine passes over the bones of your thighs and lower spine. The test takes approximately 10 to 30 minutes, depending on the parts of the body examined and the type of equipment used, according to RadiologyInfo.org. Peripheral bone density scans measure the bone density in the heel, forearm, wrist or finger. Peripheral scans can be useful in determining if patients should undergo the more extensive central scanning procedure.
Considerations
Most central DXA machines can't measure bone mineral density in the spines and hips of people who weigh over 300 pounds, according to the National Osteoporosis Foundation. If you can't fit into a central DXA machine, the Foundation recommends having a central SCA test of the forearm and a peripheral test of the heel or another bone.
Your Score
A bone density test provides doctors with two measurements to assess the health of your bones. Doctors use your T score to determine how your bones compare to those of a young adult of the same gender. Lower scores indicate low bone density, according to the National Osteoporosis Foundation. If your score is -1 or higher, your bones are normal. You have low bone mass if you score between -1 and -2.5. A score lower than -2.5 indicates that you have osteoporosis. Your Z score compares your bones to people in your age group, gender and size. A higher or lower than average score tells doctors that more tests are needed to correctly diagnose the scope of your problem.
