Bone Density Test: An Overview
A bone mineral density test (BMD), a non-invasive and painless test, is the best way to determine your bone health.
Bone density tests can:
- Hip
- Spine
- Wrist
- Finger
- Shin bone
- Heel.
Bone Density Test Results
Your bone density test results are compared to two norms: "young normal" and "age-matched." Young normal, known as your T-score, compares your BMD to optimal or peak density of a 30-year old healthy adult and determines your fracture risk, which increases as BMD falls below young-normal levels. Age-matched, known as your Z-score, compares your BMD to what is expected in someone your age and body size. Among older adults, however, low BMD is common, so comparison with age-matched norms can be misleading.
The difference between your BMD and that of a healthy, young adult is referred to as a "standard deviation" (SD). As outlined in the World Health Organization's diagnostic categories, individuals whose T-score is within one standard deviation of the "norm" are considered to have normal bone density.
Scores below the norm are indicated in negative numbers. For example, a score from -1.0 to -2.5 SD below the norm indicates low bone mass, or
osteopenia, and a score of more than -2.5 SD below the norm is considered a diagnosis of osteoporosis. For most BMD tests, -1 SD equals a 10 percent to 12 percent decrease in bone density.
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