DEXA / Bone Density Study

A bone density study, also called dual-energy x-ray absorptiometry (DEXA) or bone densitometry, is an enhanced form of x-ray technology that is used to measure bone loss. DEXA is today's established standard for measuring bone mineral density (BMD).

An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical imaging.

DEXA is most often performed on the lower spine and hips. In children and some adults, the whole body is sometimes scanned. Peripheral devices that use x-ray or ultrasound are sometimes used to screen for low bone mass. In some communities, a CT scan with special software can also be used to diagnose or monitor low bone mass (QCT). This is accurate but less commonly used than DEXA scanning.

DEXA is most often used to diagnose osteoporosis, a condition that often affects women after menopause but may also be found in men. Osteoporosis involves a gradual loss of calcium, as well as structural changes, causing the bones to become thinner, more fragile and more likely to break.

DEXA is also effective in tracking the effects of treatment for osteoporosis and other conditions that cause bone loss.

The DEXA test can also assess an your risk for developing fractures. The risk of fracture is affected by your age, body weight, history of prior fracture, family history of osteoporotic fractures and lifestyle issues such as cigarette smoking and excessive alcohol consumption. These factors are taken into consideration when deciding if a you need therapy.

On the day of the exam, you may eat normally. You should arrive approximately 15 minutes prior to test time. You should not take calcium supplements for at least 24 hours before your appointment.

You should wear loose, comfortable clothing, avoiding garments that have zippers, belts or buttons made of metal. You should avoid wearing objects of clothing with buckles or zippers from the waist down prior to test time. Objects such as keys or wallets that would be in the area being scanned should be removed.

You may be asked to remove some or all of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, eyeglasses and any metal objects or clothing that might interfere with the x-ray images.

Inform your physician if you recently had a barium examination or have been injected with a contrast material for a computed tomography (CT) scan or radioisotope scan. You may have to wait 10 to 14 days before undergoing a DEXA test.

Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation. If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby.