Bone mineral density testing, also known as bone densitometry, quickly and accurately measures the amount of calcium in certain parts of your bones. From this information, your doctor can determine how strong your bones are and what your risk of fracture is.
The test is used to detect osteoporosis, a disease in which the bone's mineral content and density are low, increasing a person's risk of fracture.
Why do menopausal women need bone mineral density testing?
There is a direct relationship between the lack of estrogen after menopause and the contribution to osteoporosis. Because symptoms of osteoporosis may not develop until bone loss is extensive, it is important for women at risk for osteoporosis to undergo periodic bone testing.
How do I prepare for a bone mineral density test?
Before having the test, be sure to notify your doctor if there is a possibility that you may be pregnant.
You do not have to change your daily routine before this test. Eat, drink, and take your medicines as you normally would. However, do not take calcium supplements (such as Tums® and Citracal®) for 24 hours before the test.
On the day of the test, remember to leave valuables, such as jewelry or credit cards, at home.
What can I expect during the test?
For the test, you may be asked to wear a hospital gown. You will then lie on your back, on a padded table, in a comfortable position.
The lumbar spine (lower back) and the hip are the skeletal sites usually examined by bone densitometry.
The procedure can be performed by many methods:
- Dual energy X-ray absorptiometry (DXA). DXA is the most accurate and best method for measuring bone mineral density. Two X-ray beams are projected onto the bones. The amounts of each X-ray beam that is blocked by bone and soft tissue are compared to estimate the bone density. DXA scanning is fast and exposes the person to very low doses of radiation. It is used to measure bone density in the hip and spine.
- Peripheral dual energy X-ray absorptiometry (P-DXA). P-DXA is a modification of the DXA test. It measures bone density in outlying or peripheral areas of the body, such as the wrist. P-DXA exposes the person to very low doses of radiation. P-DXA cannot be used to measure density of the bones in the hip and spine, and it has limited usefulness for monitoring the effects of medication used to treat osteoporosis.
- Dual photon absorptiometry (DPA). DPA uses a radioactive substance to produce radiation. It can measure the density of the bones of the hip and spine. DPA exposes the person to very low radiation.
- Ultrasound. This method uses sound waves bounced off the bones to measure bone mineral density, usually in the heel. Ultrasound is rapid, painless, and does not use potentially harmful radiation. Ultrasound cannot be used to measure density of the bones in the hip and spine, and it has limited usefulness for monitoring the effects of medication used to treat osteoporosis.
Your doctor will determine which X-ray approach is best for you.
What happens after the test?
After the test is performed, your doctor will discuss the test results with you. You can resume your usual activities immediately.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 2/26/2012...#10333