DEXA Bone Density Scan: Diagnosing Osteoporosis and Preventing Fractures

Dual-energy X-ray absorptiometry (DEXA or DXA) is the gold standard method for measuring bone mineral density (BMD) — the key indicator of bone strength and fracture risk. It is a low-radiation scan (< 1/10th of a chest X-ray) that typically measures BMD at the lumbar spine and hip, taking approximately 10–20 minutes. Results are expressed as T-score (comparison with young normal adults) and Z-score (comparison with age-matched peers).

Osteoporosis is diagnosed when the T-score is ≤ -2.5; osteopenia (low bone density) when T-score is -1.0 to -2.5. In Korea, osteoporosis is common and often underdiagnosed — partly because it is often asymptomatic until a fragility fracture occurs (typically hip, vertebral, or wrist fracture). Risk factors in Korea's population include vitamin D deficiency (very common), low physical activity, post-menopausal status, long-term corticosteroid use, and certain metabolic bone diseases.

Who should be screened: women over 65 and men over 70 routinely; post-menopausal women under 65 with risk factors (early menopause, family history of osteoporosis, low BMI, smoker, corticosteroid use); men with osteoporosis risk factors; anyone who has had a fragility fracture. In Korea, DEXA scanning is available at major hospital metabolic bone services and select private rheumatology and orthopaedic clinics, and is included in NHIS national health screening for eligible age groups.