[Lumbar vertebrae mineral content in women. Normal values obtained using quantitative digital radiography].

The bone mineral content of the lumbar spine was measured in 120 normal women, using quantitative digital radiography (Hologic QDR 1000). From the results obtained, expressed in g/cm2, the curve of the lumbar spine mineral density according to age was established, in order to demonstrate a maximum at 32.8 years, a minimum around 80.5 years with total mineral loss of 32.5% and a maximum speed of bone loss at 56.5 years (6 years after the average menopausal age). Moreover, from measurements in 30 osteoporotic women, the value of the fracture threshold was estimated at 0.730 g/cm2.