You’re probably aware of the risks of osteoporosis, the debilitating disease that makes bones fracture as they age. But as painful as a broken bone can be, the good news is that tests that help identify the risk of fractures, like the Bone Mineral Density (BMD) test, are painless and readily available.
While the BMD test can’t prevent osteoporosis, your doctor can use the information from it to track changes in your bone mass over time and help determine appropriate treatments if needed.
How it works
Most bone density testing is performed either at a hospital or in a doctor’s office. Using X-ray or ultrasound machines, a technician measures the amount of mineral in a bone, typically in the hip and the lumbar spine. Some BMD machines read bone mass of the heel or elbow, but that may give a false sense of security because bone density varies throughout the body. The hip and spine are considered the most accurate measures.
The BMD may provide two numbers: a T-score, which measures how your bone mass compares with that of a healthy 30-year-old woman, and a Z-score, which compares you to scores of other women who are the same age. Your physician can help you interpret your scores and suggest treatment.
In general, doctors suggest that women have their bone density measured at the onset of menopause, or by age 65 to 70, and then at least every two years. Women at high risk of osteoporosis should begin testing at age 50. High-risk factors include low body weight, family history and previous bone fractures.
Beyond the BMD test
The concern with these guidelines, is that they shouldn’t necessarily be the only factor in preventing and treating osteoporosis. Other factors can also help doctors assess your risk of osteoporosis, including whether or not you smoke, drink alcohol or use steroids, as well as ethnicity, age and family history.
For that reason, many doctors like to combine traditional BMD tests with the World Health Organization’s new Fracture Assessment Algorithm (FRAX), a calculator that helps assess the risk of bone-breaking fractures based on additional factors. You can find the FRAX calculator online at www.shef.ac.uk/FRAX/tool.jsp?locationValue=2.
By the numbers
The result of your BMD test usually will be a number between 1 and -3, which shows how your bone density compares with that of a healthy 30-year-old woman (your T-score). Here’s a guide:
* 0 – average bone density
* 1 and above — higher than normal bone density
* -1.1 to -2.5 — low bone mass, which can be a cause for concern. Some physicians recommend treatment for patients with a score of -2.0 or below.