What T-score defines osteoporosis?

• A. A T-score of -1.0 or higher.
• B. A T-score of -2.5 or lower.
• C. A T-score of 0.
• D. A T-score of -3.0 or higher.

Answer: (B)

Osteoporosis is defined by bone mineral density measured with DXA and expressed as a T-score, which shows how many standard deviations your density is from a healthy young adult. A T-score of -2.5 or lower means your bone density is 2.5 standard deviations below the young reference mean, and this threshold identifies osteoporosis with substantially increased fracture risk. In practice, this cut-off is used to diagnose osteoporosis and guide treatment decisions. (A Z-score, by contrast, compares to age-matched peers and isn’t used to diagnose osteoporosis in adults.)