This test measures a person's bone density in order to diagnose osteoporosis, a disease in which the bones become less dense. Testing bone mineral density helps to both diagnose the disease and tell how far it has progressed.

Who is a candidate for the test?

The following women are likely to be asked by a doctor to have this test done:

How is the test performed?

Most methods for measuring bone mineral density are fast and painless. The methods involve taking either dual energy x-rays (DEXA) or CAT scans of the bones of the spine, wrist, arm, or leg. One new method that was recently approved by the FDA uses ultrasound of the heel. It only takes about a minute to do and is less costly than the other methods, but it's not as sensitive a test.

Most centers ask the woman to undress and put on an exam gown. She will also be asked to remove any jewelry or metal that could interfere with the test.

During the DEXA test, the woman lies face up on the x-ray table while the system scans an area of her body, usually the lower spine or hip. The test takes only a few minutes and the x-ray dose is small.

During a CAT scan, the person lies on a narrow table that slides into a doughnut-shaped gantry. This is a frame that houses the various parts of the CT machine. A series of x-rays are then taken of the area being tested, usually the lower spine and then the hip, by a camera that revolves completely around the area. The picture this method makes is a highly detailed cross-section of the area.