Osteoporosis is the main cause of bone fragility. The diagnosis is suspected in the presence of low-energy traumatic fracture and/or low bone mineral density. Vertebral fractures may be asymptomatic, and they are under-diagnosed. Dual energy X-ray absorptiometry is the gold standard of bone density measurement, at the lumbar spine, and hip. Providing quality control of the device and assessments, the measurements are accurate and precise; BMD is the basis of osteoporosis diagnostic and risk fracture evaluation. Osteoporosis may be related to malignant and metabolic diseases, which must be checked before any treatment.