Diagnosis of Osteoporosis-part 2

X Ray Tests
If you have back pain, your doctor may order an x ray of your spine to determine whether you have had a fracture. An x ray also may be appropriate if you have experienced a loss of height or a change in posture. However, since an x ray can detect bone loss only after 30 percent of the skeleton has been depleted, the presence of osteoporosis may be missed.

Bone Mineral Density Tests
A bone mineral density (BMD) test is the best way to determine your bone health. BMD tests can identify osteoporosis, determine your risk for fractures (broken bones), and measure your response to osteoporosis treatment. The most widely recognized bone mineral density test is called a dual-energy x-ray absorptiometry or DXA test. It is painless: a bit like having an x ray, but with much less exposure to radiation. It can measure bone density at your hip and spine.
During a BMD test, an extremely low energy source is passed over part or all of the body. The information is evaluated by a computer program that allows the doctor to see how much bone mass you have. Since bone mass serves as an approximate measure of bone strength, this information also helps the doctor accurately detect low bone mass, make a definitive diagnosis of osteoporosis, and determine your risk of future fractures.
BMD tests provide doctors with a measurement called a T-score, a number value that results from comparing your bone density to optimal bone density. When a T-score appears as a negative number such as -1, -2 or -2.5, it indicates low bone mass. The more negative the number, the greater the risk of fracture.
Although no bone density test is 100 percent accurate, this type of test is the single most important predictor of whether a person will fracture in the future.

Bone Scans
For some people, a bone scan may be ordered. A bone scan is different from the BMD test just described, although the term “bone scan” often is used incorrectly to describe a bone density test. A bone scan can tell the doctor whether there are changes that may indicate cancer, bone lesions, inflammation, or new fractures. In a bone scan, the person being tested is injected with a dye that allows a scanner to identify differences in the conditions of various areas of bone tissue.