When to Order DEXA Scan
Order DEXA scanning for all women ≥65 years and men >70 years, and for younger postmenopausal women and men ≥50 years with specific risk factors including prior fracture, glucocorticoid use ≥3 months, significant height loss, or medical conditions associated with bone loss. 1
Age-Based Screening Recommendations
Routine Screening by Age and Sex
- Women ≥65 years: Universal DEXA screening recommended 1
- Men >70 years: Universal DEXA screening recommended 1
- Postmenopausal women <65 years: Use a 2-step approach with fracture risk assessment (e.g., FRAX) followed by DEXA if elevated risk 1
- Men 50-70 years: Screen only if risk factors present 1
The 2025 USPSTF guidelines emphasize that DXA is the gold standard for osteoporosis screening because it correlates with bone strength, clinical fracture outcomes, uses low radiation, and was the test used in nearly all bone-conserving pharmacotherapy trials 1.
Risk Factor-Based Screening (Age ≥50 Years)
Order DEXA immediately if any of the following are present:
Fracture History:
- Any adult fracture (low-trauma or otherwise) 1
- Self-reported but undocumented prior vertebral fracture 1
Height Loss:
- Historical height loss ≥4 cm (≥1.5 inches) from peak height 1
- Prospective height loss ≥2 cm (≥0.8 inches) from last measurement 1
- Presence of kyphosis 1
Medication Exposures:
- Glucocorticoid therapy ≥5 mg prednisone equivalent daily for ≥3 months 1
- Androgen deprivation therapy for prostate cancer 1
Medical Conditions Associated with Bone Loss:
- Hyperparathyroidism 1
- Rheumatoid arthritis 1
- Type 2 diabetes (note: DXA may underestimate fracture risk in this population) 1
- Malabsorption syndromes 1
- Chronic kidney disease 1
Special Populations Requiring DEXA
Immediate Scanning Required:
- Spinal cord injury patients: Scan total hip, proximal tibia, and distal femur as soon as medically stable after injury 1
- Transgender persons: Base screening on hormone therapy compliance, gonadal removal status, and additional risk factors 1
- Post-pubertal transgender adolescents: On GnRH agonists without sex steroid replacement 1
Younger Adults (<50 Years or Premenopausal Women):
Consider DEXA in premenopausal women and men <50 years with:
Anatomic Sites to Scan
Standard measurement sites 1:
- Lumbar spine (L1-L4)
- Total hip
- Femoral neck
- One-third radius (if indicated, particularly in hyperparathyroidism or when other sites unavailable)
Follow-Up DEXA Timing
Rescanning Intervals:
- General monitoring: 1-5 years after starting or changing therapy, depending on clinical circumstances 1
- Prostate cancer on ADT: 1-2 year intervals 1
- Spinal cord injury: Minimum 12 months after therapy initiation, then 1-2 year intervals 1
- After fracture or new risk factors: Rescan promptly but do not delay treatment for secondary fracture prevention 1
- Before bisphosphonate drug holiday: Monitor during planned treatment interruption 1
The evidence on optimal screening intervals remains limited, but the USPSTF notes that rescanning should be guided by clinical circumstances rather than arbitrary time intervals 1.
Common Pitfalls to Avoid
Do not order DEXA when:
- Acute back pain without risk factors for osteoporosis 1
- Results will not influence management decisions 1
- Artifacts will compromise interpretation (severe spine osteoarthritis, hip prosthesis, recent contrast studies) 1
Critical interpretation considerations:
- Exclude vertebrae with fractures, severe osteoarthritis, or T-score differences >1.0 from adjacent vertebrae 1
- Use contralateral hip if one side has prosthesis or hardware 1
- DXA may underestimate fracture risk in glucocorticoid-induced osteoporosis and type 2 diabetes 1
The lowest T-score at any measured site should be used for diagnosis when T-score ≤-2.5 defines osteoporosis per WHO criteria 1.