Table 4.

WHO definitions of osteoporosis based on BMD (26)

Classification	Bone Mineral Density	T Score
Normal	Within 1 SD of the mean level for a young adult reference population	T score at −1.0 and above
Low bone mass (Osteopenia)	Between 1 and 2.5 SD below that of the mean level for a young adult reference population	T score between −1.0 and −2.5
Osteoporosis	2.5 or more below that of the mean level for a young adult reference population	T score at or below −2.5
Severe or established osteoporosis	2.5 or more below that of the mean level for a young adult reference population with fractures	T score at or below −2.5 with one or more fractures

WHO: World Health Organization; BMD: bone mineral density; SD: standard deviation