A bone age scan, commonly referred to as a bone mineral density test or DEXA scan, is a test that helps physicians predict the likelihood of a person developing a bone disorder in the future. This test is often confused with a bone scan, which is a test that physicians prescribe for patients to determine abnormalities related to disease such as arthritis or cancer.
Function
A DEXA scan will help determine the amount of calcium and other minerals in a section of bone. The physician uses this information, along with other risk factors such as age, to assess for weakness in the bone. MayoClinic.com explains that a bone density scan can help a physician confirm a diagnosis of osteoporosis. It also aids in monitoring osteoporosis and in assessing a person's risk for a broken bone later in life by identifying decreases in bone density before a break occurs.
Procedure
Several machines can perform the bone age scan. The most common method, known as a DEXA scan, involves the patient lying on a table while a low-dose X-ray scanner passes over the body. The machine will commonly photograph the lower spine and hips, according to the National Institutes of Health. Technicians can use smaller machines to measure the density of smaller bones such as the wrist, fingers, leg or heels. People are more likely to find these machines in shopping centers, health fairs and small clinics or pharmacies. However, it is a central DEXA scan of the lower spine and hip that best gives physicians the information to predict risk factors.
Risks
There is little risk associated with this test. DEXA scans involve only one-tenth the radiation of a chest X-ray. The University of Maryland Medical Center states that experts believe the risk is very low compared to the benefits of early diagnosis of osteoporosis.
Normal Results
Tests results are commonly reported as a T score and a Z score. A T score will compare the person's bone density to healthy young women, while the Z score compares the bone density results with that of other people of the person's age, gender and race. A negative number in either score means that a person's bones are thinner than normal. The more negative the number, the higher a person's risk of bone fracture. Normal T score range is -1.0 or higher, according to the National Institutes of Health. Z scores vary depending on age, gender and race.
Abnormal Results
A bone mineral density test does not diagnose a fracture, but it can often allow a physician to predict a future fracture. This allows the physician to implement a course of preventive treatments such as medications to increase or maintain bone density to help prevent falls that can cause fracture. A T score from -1.0 to -2.5 indicates the beginning of bone loss known as osteopenia, according to National Institutes of Health, while a T score lower than -2.5 indicates a diagnosis of osteoporosis.
