SPINAL SCANS made with dual-energy x-ray absorptiometry (DEXA) are used to diagnose osteoporosis. Bone in the lumbar (lower) spine of someone with osteoporosis (left) is much less dense than that in the spine of a healthy individual (right). The vertebrae have also begun to collapse, shifting the spine out of alignment (indicated by red lines). Image: FAYE LIQUE Maine Center for Osteoporosis Research and Education
Should older women be screened to see if they are at risk for osteoporotic fractures? Ever since tools for measuring bone mineral density became available to doctors, this question has elicited intense controversy.
Studies show that density measurements--of the hip or spine, for example--can reliably predict a person's risk for a fracture at that site. The "gold standard" for measuring bone mineral density is a technology called dual-energy x-ray absorptiometry (DEXA), which uses x-rays but involves very little radiation exposure. DEXA diagnoses osteoporosis when it finds that the measure of density is much lower than the average for healthy young women at the spine, hip or wrist (2.5 or more standard deviations from the mean).