[Diagnosis with bone mass]

In diagnostic criteria of osteoporosis proposed by WHO, the severe osteoporosis is defined as a patient with a value for BMD or BMC more than 2.5SD below the young adult mean value in the presence of one or more fragility fractures. When severe fragility fracture occurs from the second to forth lumbar vertebra, the lumbar BMD could be over-estimated. On the other hand, when the lumbar BMD is markedly low, the demarcation of bone contour is incomplete, and the precision of the BMD measurement decreases. Thus, in the severe osteoporosis it is necessary to be careful in the diagnosis with bone mass using DXA.