What it is
A T-score compares a person's BMD with a young-adult reference. It is commonly used for postmenopausal women and men age 50 or older.[1,2]
Why it matters
It turns BMD into a standardized adult classification signal, but it does not replace fracture history or clinical assessment.[2]
Root causes of abnormal values
- Calculation core: A T-score changes when measured BMD is farther above or below the young-adult reference mean. The chain is measured BMD -> young-adult reference database -> standard-deviation comparison.[1,2]
- Adult classification layer: In the intended adult context, T-score can help classify low bone mass or osteoporosis categories, but it is not the same as a fracture-risk score. The same T-score has to be read with age, sex, skeletal site, scanner context, and fracture history.[1,2]
- Reading boundary: BioConst can explain the reference-comparison logic, but it does not apply T-score to children or younger adults, diagnose a reader, or recommend screening or treatment from one number.[2,3]
What it affects
- NIAMS describes T-score -1 or higher as healthy bone, between -1 and -2.5 as osteopenia / low bone density, and -2.5 or lower as a possible osteoporosis category.[1]
- ISCD states osteoporosis may be diagnosed in postmenopausal women and men age 50 or older when central DXA T-score is -2.5 or lower at accepted skeletal sites.[2]
Interpretation traps
- The same number means less when the person is younger, premenopausal, pediatric, has unusual skeletal disease, or has technical artifacts.[2]