Bone Mineral Density Assessment A bone densitometer, Lunar Prodigy Primo (pr + 351035), will be used to measure the patients' bone mineral density (BMD), expressed in g/cm2, by dual-energy x-ray absorptiometry (DXA). The double-energy X-ray densitometry of the skeleton or specific sites such as the spine and the hip is based on the X-rays absorption by the calcium crystals in the bone. The lumbar spine regions between L1 and L4 and those of the total proximal femur will be assessed. The examination will be held under appropriate conditions, according to the technical quality controls. The coefficient of variation for the lumbar spine and total proximal femur will be obtained based on these results. The low BMD will be defined by the reduction greater than -2.0 standard deviations from the reference value mean of healthy individuals, adjusted according to height, age and gender (Z score), in compliance with the official positions of the International Society for Clinical Densitometry (ISCD).