Common Questions
How are osteoporosis and osteopenia defined?
WHO Diagnostic Categories 1994: BMD*-Based Definition of Osteoporosis/Osteopenia
In 1994, the World Health Organization Osteoporosis Study Group established these diagnostic categories using the young adult women as the referent group (1). The standard deviation from the young-adult mean, "T-score," defines the diagnostic categories.
- Normal: T-score + or -1 SD
- Osteopenia: T-score - 1 to -2.5 SD
- Osteoporosis: T-score -2.5 or less
- Severe Osteoporosis: T-score -2.5 or less and fragility fracture
* BMD = bone mineral density
The WHO Study Group considered other approaches to the definition of osteoporosis, including the use of different normative groups. The current definition was selected for its simplicity and reasonable predictive value. The Group preserved the older, non-numeric definition, which reads:
"A disease characterized by low bone mass, microarchitectural deterioration of bone tissue or both, leading to skeletal fragility." (1,2)
- Osteoporosis Consensus Development Conference. AJM 1991.
- Heaney RP. Bone mass, bone fragility, and the decision to treat. JAMA 1998; 280(24): 2119-20. No abstract available.