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

DXA 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 provides an accurate reading but is less commonly used than DXA scanning.

DXA scans are used to diagnose osteoporosis before fractures occur, predict the chances of future bone fractures, determine the rate of bone loss and monitor the effects of bone replacement therapy.

 

WHY IS IT IMPORTANT TO HAVE A BONE MINERAL DENSITY TEST?

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A bone mineral density (BMD) test or DXA scan (dual-energy x-ray absorptiometry) is considered the most accurate test for bone density. While standard x-rays show changes in bone density after about 40% of bone loss, a DXA scan can detect changes after about a 1% variation in bone mass. This scan lasts about 10 minutes and exposes the patient to less radiation than a standard chest x-ray. A bone mineral density test can tell if you are at risk for osteoporosis, a disease in which the bones become a weak and are more likely to break. Osteoporosis can be prevented and treated if diagnosed early.

 

 WHO SHOULD BE TESTED?

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• All postmenopausal women under age 65 who have one or more additional risk factors for osteoporosis in addition to being postmenopausal and female)
• All women age 65 and older regardless of additional risk factors
• Postmenopausal women who have a past history of a fracture
• Women who are considering therapy for osteoporosis
• Women who have been on hormone replacement therapy (HTR/ERT) for prolonged period

 

WHAT ARE THE RISK FACTORS?

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Some common risk factors include being female, advanced aging, being Caucasian or Asian, low bone mass, small body frame, family history of osteoporosis, estrogen deficiency due to menopause, anorexia nervosa, use of certain drugs, smoking, and excessive alcohol intake.

 

WHAT ARE THE RISK FACTORS?

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Some common risk factors include being female, advanced aging, being Caucasian or Asian, low bone mass, small body frame, family history of osteoporosis, estrogen deficiency due to menopause, anorexia nervosa, use of certain drugs, smoking, and excessive alcohol intake.

 

WHAT TO EXPECT DURING THE EXAM

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During the exam, you will be instructed to lie on your back while your hip ad spine are scanned by the DXA machine to determine your BMD scores and risk of fractures. With most types of machines, you will be fully dressed and the test usually takes 10 minutes. You should refrain from taking calcium supplements for 24 hours prior to the test as the tablet could interfere with test results.

 

HOW OFTEN TO REPEAT A BMD TEST

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Patients taking an osteoporosis medication should repeat their BMD test every one – two years, according to the National Osteoporosis Foundation (NOF). Some healthcare providers may have certain patients repeat their BMD test after one year.