Guidelines for DEXA Scan
DEXA (Dual-Energy X-ray Absorptiometry) scans should be performed in women aged 65 years and older, men aged 70 years and older, and earlier in individuals with specific risk factors for osteoporosis to reduce morbidity and mortality from fragility fractures. 1, 2
Recommended Screening Population
Age-Based Recommendations:
- Women:
- Age 65 years and older: Universal screening
- Age 50-64 years: Selective screening based on risk factors
- Men:
- Age 70 years and older: Universal screening
- Age 50-69 years: Selective screening based on risk factors
High-Risk Individuals (Any Age) Who Should Be Screened:
- History of fragility fracture
- Long-term glucocorticoid therapy (current or recent)
- Height loss ≥ 1.5 inches (historical) or ≥ 0.8 inches (prospective)
- Medical conditions associated with bone loss:
- Hyperparathyroidism
- Rheumatoid arthritis
- Malabsorption syndromes
- Chronic inflammatory conditions
- Androgen deprivation therapy for prostate cancer
- Premature menopause or hypogonadism
- Spinal cord injury
Anatomical Sites for Measurement
Primary Sites:
- Lumbar spine (L1-L4)
- Proximal femur (total hip and femoral neck)
Secondary Sites (When Primary Sites Cannot Be Assessed):
- Distal forearm (one-third radius)
- For spinal cord injury patients: total hip, proximal tibia, and distal femur
Diagnostic Classification (WHO Criteria)
| T-score | Diagnosis |
|---|---|
| > -1.0 | Normal |
| -1.0 to -2.4 | Osteopenia (Low bone mass) |
| ≤ -2.5 | Osteoporosis |
Follow-up Recommendations
- Normal BMD: Every 2-3 years
- Osteopenia: Every 2 years
- Osteoporosis on treatment: 1-2 years after initiating therapy, then every 2 years
- High-risk for rapid bone loss: Annual scans (e.g., glucocorticoid therapy)
- After fracture or development of new risk factors: Immediate reassessment
Special Populations
Transgender Individuals:
- Z-scores should be calculated using reference data conforming with the individual's gender identity
- For gender non-conforming individuals, use reference data for sex recorded at birth
Spinal Cord Injury:
- DXA scan as soon as medically stable
- Include evaluation of total hip, distal femur, and proximal tibia
- Follow-up every 1-2 years
Common Pitfalls to Avoid
Positioning errors: Ensure proper patient positioning
Artifacts: Identify and account for:
- Degenerative changes in spine (exclude affected vertebrae)
- Vertebral fractures (exclude affected vertebrae)
- Surgical hardware or prostheses (scan contralateral side)
- Aortic calcification
Interpretation errors:
- Using T-scores instead of absolute BMD values (g/cm²) for follow-up comparisons
- Not using the same DXA machine for serial measurements
- Not accounting for height/size differences in very tall or short individuals
Reporting errors:
- Incomplete documentation of patient demographics and risk factors
- Failure to note technical limitations or artifacts
Components of a Standard DXA Report
- Patient demographics (name, age, sex, height, weight)
- Menopausal status (if applicable)
- Indication for testing
- Technical quality and limitations
- BMD measurements in g/cm² and T-scores for each site
- Fracture risk assessment (FRAX if appropriate)
- Diagnosis based on WHO criteria
- Recommendations for follow-up
By following these guidelines, clinicians can appropriately utilize DEXA scanning to identify patients at risk for osteoporotic fractures and implement timely interventions to reduce morbidity and mortality associated with fragility fractures.