<s>[INST] What is a bone density test (DXA)? [/INST] A DXA scan or a bone mineral density (BMD) test is the current standard to diagnose osteoporosis. The test measures the quantity of bone at specific locations in the body—the lower back bones (lumbar region) and the upper end of the thighbone where it connects to the pelvis (total hip and its subdivisions—the femoral neck and trochanter). These locations are used for two primary reasons: 1) they have a large quantity of trabecular bone—the spongy, lattice-like bone on the inside—where we first begin to see bone loss as we age; and 2) measurements taken at these locations can be more easily replicated to be able to monitor changes in the quantity or density of bone over time. Source: American Bone Health. Link: https://americanbonehealth.org/frequently-asked-questions/. Field: Rheumatology. Disease: Ostoeporosis </s>