[What to expect from the measurement of bone mass?]

The development of non-invasive methods to measure the mineral content of bones, represent a major advance for the diagnosis and the follow-up of these demineralizing diseases. The use of these techniques, including biphotonic absorptiometry, is based on a close relationship between mineral content and bone resistance. However we are lacking prospective data permitting to evaluate the value of bone density in terms of subsequent risk of fracture. The presence of interpopulation and inter apparatus variations, the various ways of expressing the results, make it necessary, prior to any study, to specify reference value that are appropriate to each center. Also, the knowledge of short and long-term coefficients of variation, in normal and osteoporotic patients, is absolutely necessary to an accurate evaluation of the variations with time. Measurement of the mineral content in bones enables to consider the early diagnosis of osteoporosis before the fracture stage, and screening of risk patients. Because of their therapeutic implications, it would be desirable that a consensus be established on a precise definition of these densitometric notions.