Table 1.

WHO classification of osteopenia/osteoporosis. Bone mineral density (BMD) is expressed in standard deviations (SD) relative to a sex-specific, young-adult mean (known as the T-score). (WHO, 1994).

BMD category	Definition
Normal	BMD no greater than 1 SD below the reference mean (T-score ≥ -1)
Osteopenia	BMD between 1 and 2.5 SD below the reference mean (T-score < -1 but > -2.5)
Osteoporosis	BMD 2.5 SD or more below the reference mean (T-score ≤ -2.5)
Severe osteoporosis	BMD 2.5 SD or more below the reference mean (T-score ≤ -2.5) PLUS one or more fragility fractures