What is the only test that can definitively diagnose osteoporosis?

• A. A serum calcium test
• B. A bone density test (DXA)
• C. A physical examination
• D. A magnetic resonance imaging scan

Answer: (B)

A bone density test, specifically a Dual-energy X-ray Absorptiometry (DXA) scan, is the only test that can definitively diagnose osteoporosis. This test measures the bone mineral density (BMD) in various skeletal sites and provides essential information regarding bone health.

The World Health Organization defines osteoporosis based on T-scores obtained from bone density results. A T-score of -2.5 or lower is indicative of osteoporosis. The DXA scan is a highly accurate method that allows for the assessment of bone density and helps in evaluating fracture risk.

Other tests, like serum calcium levels, a physical examination, and magnetic resonance imaging (MRI), play supportive roles in assessing bone health but do not provide definitive evidence of osteoporosis. Serum calcium levels can indicate nutritional status or other conditions but are not specific to bone mass. A physical examination may suggest issues related to bone health through observation of symptoms or signs, but it cannot quantify bone density. An MRI might be useful for evaluating bone structure and detecting fractures, but it is not designed to assess bone mineral density in the context of diagnosing osteoporosis.