a routine x-ray can reveal osteoporosis of the bone because the bones appear much thinner and lighter than normal bones. unfortunately by the time x-rays can detect osteoporosis at least 30% of the bone has already been lost. in addition x-rays are not accurate indicators of bone density. thus the appearance of the bone on x-ray often is affected by variations in the degree of exposure of the x-ray film. the national osteoporosis foundation the american medical association and other major medical organizations recommend a dual-energy x-ray absorptiometry scan (dxa formerly known as dexa) for diagnosing osteoporosis. dxa measures bone density in the hip and the spine. the test takes only five to 15 minutes to perform exposes patients to very little radiation (less than one-tenth to one-hundredth of the amount used on a standard chest x-ray) and is quite precise. the bone density of the patient is compared to the average peak bone density of young adults of the same sex and race. this score is called the "t score " and it expresses the bone density in terms of the number of standard deviations (sd) below peak young adult bone mass. osteoporosis is defined as a bone density t score of -2. 5 or below. osteopenia (between normal and osteoporosis) is defined as bone density t score between -1 and -2. 5. it is important to note that while osteopenia is considered a lesser degree of bone loss than osteoporosis it nevertheless can be of concern when it is associated with other risk factors (such as smoking cortisone steroid usage rheumatoid arthritis family history of osteoporosis etc. ) that can increase the chances for developing vertebral hip and other fractures. in this setting osteopenia may require medication as part of the treatment program.
how is osteoporosis diagnosed?