Which T-score definition corresponds to osteoporosis at the spine, hip, or femoral neck?

• A. T-score between -1.0 and -2.5
• B. T-score ≤ -2.5 at the spine, hip, or femoral neck (high fracture risk)
• C. T-score ≥ -1.0 (normal bone density)
• D. T-score ≤ -3.0 at the spine only

Answer: (B)

Bone mineral density is considered abnormal enough to be called osteoporosis when it falls 2.5 standard deviations below the young healthy adult mean, and this threshold is applied to sites where fractures are most likely to occur—typically the spine and the hip (femoral neck). So a T-score of -2.5 or lower at the spine, hip, or femoral neck indicates osteoporosis with high fracture risk. The other options describe osteopenia (between -1.0 and -2.5) or normal density (above -1.0), or an overly restrictive criterion (spine only at -3.0), which doesn’t match the standard diagnostic definition across key fracture-prone sites.