The bone density test results are compared to the BMD of a healthy young adult, and then gives a T-score. A score of 0 means your BMD is equal to the norm for a healthy young adult.
Differences between your bone mineral density and that of the healthy young adult norm are measured in units called standard deviations (SDs). The more standard deviations below 0, indicated as negative numbers, the lower your BMD and the higher your risk of fracture.
A bone mineral density (BMD) test can provide a picture of bone health. The test can identify osteoporosis, determine risk for fractures, and measure your response to osteoporosis treatment.
The most commonly used test is called a central dual-energy x-ray, central DXA test. The test can measure bone density at your hip and lumbar spine.
Bone density test results
Normal bone density is within 1 SD (+1 or −1) of the young adult mean.
Low bone density is between 1 and 2.5 SD below the young adult mean (−1 to −2.5 SD).
In case of osteoporosis, the bone density is 2.5 SD or more below the young adult mean (−2.5 SD or lower). It is literally means porous bone.
Osteoporosis is a disease that thins the inside of bones so much that even a minor fall or bump against a car door or piece of furniture may cause a fracture. Wrist, hip and spine fractures are more common in this case.
Bone density is more than -2.5 SD below the young adult means that is the case of severe Osteoporosis.