A T-score is used to compare bone density to which reference?

• A. Bone density of a healthy 30-year-old adult
• B. Age-matched peers
• C. Patient’s height
• D. Patient’s weight

Answer: (A)

The main idea is that the T-score benchmarks a person’s bone density against peak bone mass from a healthy young adult. This score shows how many standard deviations your density is from the reference peak density, typically in a person around 30 years old of the same sex. Because it’s anchored to peak bone mass rather than to age-mmatched peers, a T-score reflects how much density you’ve lost compared to when bones are strongest, which is what clinicians use to assess osteoporosis risk.

That’s why the best reference is a healthy young adult at peak bone density, not peers of the same age. A different score, the Z-score, would compare to age-, sex-, and sometimes ethnicity-m matched peers. Height or weight aren’t used as the reference for this calculation.