What is the first-line diagnostic test for osteoporosis?

• A. DEXA bone mineral density testing
• B. X-ray of the hip
• C. MRI of the spine
• D. Ultrasound bone density

Answer: (A)

Measuring bone mineral density with dual-energy X-ray absorptiometry (DEXA) is the first-line diagnostic test for osteoporosis because it directly quantifies bone density and provides a T-score that classifies bone health and guides fracture risk assessment. This approach detects osteoporosis earlier and more reliably than imaging that only reveals fractures once bone loss is advanced. A hip X-ray or MRI can show structural problems or existing fractures but does not reliably quantify density for diagnosis, and ultrasound-based density is not considered a standard diagnostic tool for osteoporosis. In practice, a T-score of -2.5 or lower on DEXA confirms osteoporosis, while -1.0 to -2.5 indicates osteopenia, guiding further management.