Who should get a bone density test?

• What is a bone density test?
• How is a bone density test done?
• What causes osteoporosis (bone loss)?
• Bone density test results

Bone densitytesting is used to assess the strength of the bones and the probability offracturein persons at risk forosteoporosis. The test, referred to as bone densitometry orbone mineral densityscan (BMD), is a simple, noninvasive procedure that takes just minutes.

Unlike abone scan, bone densitometry testing does not involve the administration of radioactive contrast material into the bloodstream.

The most commonly used test is known as a dual energy X-ray absorptiometry (DEXA)扫描,并与设备,它可以执行measure bone density in the hip and spine, or smaller peripheral devices to measure bone density in the wrist, heel, or finger. The central bone density device is used in hospitals and medical offices, while the smaller peripheral device is available in some drugstores and in screening sites in the community. The DEXA scan involves a much smallerradiationexposure than a standardchest X-ray.

In premenopausal women, estrogen produced in the body maintains bone density. Following the onset ofmenopause, bone loss increases each year and can result in a total loss of 25%-30% of bone density in the first five to ten years aftermenopause. Your doctor can help you decide when and if you need a bone density test. In general, this testing is recommended for women 65 and older along with youngerpostmenopausalwomen who have further risk factors forosteoporosis, including:

• 骨的历史fracturesas an adult or having a close relative with a history of bone fractures
• Smoking
• Vitamin D deficiency, which can occur as a result of certain medical conditions
• Excessivealcoholorcaffeineconsumption
• Weight loss或低体重t; small-boned body frame
• Earlymenopauseor late onset of menstrual periods
• Physical inactivity
• Taking a medication [such asprednisoneorphenytoin, (Dilantin)] known to cause bone loss
• Low estrogen levels
• Hyperparathyroidism
• Hyperthyroidism

Your bone density measurement will be compared to the average peak bone density of young adults of the same sex and race. The results are usually reported as a "T score" and a "Z score." The T score compares your bone density with that of healthy young women, while the Z score is a comparison of your bone density with that of other people of the same age, gender, and race.

In either the T or Z score, a negative number means you have thinner bones than the standard. The more negative the number, the greater the degree of bone loss.

Osteoporosisis defined as the beginning of bone loss and corresponds to a T score of -1 to -2.5. A T score lower than -2.5 is indicative ofosteoporosis.

For more information, please read the following MedicineNet article:

• Bone Density Scan

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