At what age should Dual-Energy X-ray Absorptiometry (DEXA) scans be started?

DEXA Scan Screening Age Guidelines

DEXA scans should be initiated at age 65 for women and age 70 for men for routine screening, while younger individuals should only undergo testing if they have specific risk factors for bone loss. 1

Standard Screening Recommendations

• Women aged 65 and older: Routine DEXA screening recommended 2, 1
• Men aged 70 and older: Routine DEXA screening recommended 2, 1
• Younger individuals: Screening only with risk factors present 1, 3

Risk Factors Warranting Earlier Screening

For postmenopausal women under 65 and men aged 50-69, DEXA scanning is recommended only with the presence of specific risk factors:

• Previous fragility fracture 1
• Low body weight (less than 127 lb/58 kg) 1
• Parental history of hip fracture 1
• Long-term glucocorticoid therapy (≥5 mg prednisone daily for ≥3 months) 1
• Chronic inflammatory conditions (e.g., rheumatoid arthritis) 1
• Conditions causing malabsorption or malnutrition 1
• Untreated premature menopause or hypogonadism 1
• Organ transplantation 1
• Prolonged immobilization 1
• Endocrine disorders affecting bone (hyperparathyroidism, hyperthyroidism, Cushing syndrome) 1
• Medications known to cause bone loss (anticonvulsants, androgen deprivation therapy, aromatase inhibitors, chronic heparin) 1

Clinical Considerations

The evidence strongly supports waiting until age 65 for women and 70 for men before routine screening. Research has shown that osteoporosis is relatively infrequent in women with distal forearm fractures below age 65, with only 8.8% having femoral neck T-scores below -2.5 when using the NHANES III database 4. This suggests limited benefit from universal screening in younger populations without risk factors.

Recommended Screening Intervals

• High-risk individuals: Every 1-2 years 1
• Standard risk individuals with risk factors: Every 2 years 1

Important Clinical Pitfalls

1. Degenerative changes: In patients over 50 with advanced degenerative changes of the spine, careful image inspection is necessary as these changes may falsely elevate BMD values 1

2. Risk factor assessment limitations: Weight alone is an unreliable predictor of low BMD (area under ROC = 70%), making comprehensive risk factor assessment essential 4

3. Reference database impact: The choice of reference database (local vs. NHANES III) can significantly affect the proportion of patients classified as having osteoporosis, potentially influencing treatment decisions 4

4. Special populations: For patients with specific conditions like spinal cord injury, DEXA scans should include total hip, proximal tibia, and distal femur measurements 1

5. Gender considerations: For transgender individuals, Z-scores should be calculated using reference data conforming with the individual's gender identity 1

By following these evidence-based guidelines for DEXA scan initiation, clinicians can effectively identify patients at risk for osteoporotic fractures while avoiding unnecessary testing in low-risk populations.