DEXA Scan Recommendations for Osteoporosis
All women ≥65 years and men ≥70 years should undergo initial DEXA screening of the lumbar spine and hip, with standard follow-up scans every 2 years for both treated and untreated patients. 1
Initial Screening: Who Needs a DEXA Scan
Standard Age-Based Screening
- Women ≥65 years and men ≥70 years should receive DXA of the lumbar spine and hip(s) as the primary screening modality 1
- Postmenopausal women and men ≥50 years with specific risk factors require earlier screening 1
Risk Factors Triggering Earlier Screening
Younger individuals (<65 for women, <70 for men) should undergo DEXA if they have: 1
- Previous fragility fracture
- Chronic glucocorticoid therapy (≥5 mg prednisone equivalent daily for ≥3 months)
- Chronic inflammatory conditions
- Malabsorption disorders
- Untreated premature menopause
When NOT to Screen
- Premenopausal women and men <50 years should only undergo screening if they have medical conditions or medications that adversely affect bone density 1
- DEXA should be considered only if the 10-year risk of major osteoporotic fracture is >10% 2
Technical Specifications: What to Scan
Standard Protocol
DXA of the total spine, hip, and femoral neck provides the most comprehensive evaluation of fracture risk 1
Alternative Sites for Special Circumstances
When patients have advanced degenerative spine changes or scoliosis, use: 1
- DXA of the distal forearm, OR
- Quantitative CT (QCT) of the lumbar spine and hip
Critical pitfall: Do not rely solely on spine DXA in patients with degenerative disease, as spuriously elevated BMD from spondylosis occurs in >81% of falsely elevated measurements 1
Follow-Up Scan Frequency: When to Repeat
Standard Monitoring Interval
Every 2 years for both treated and untreated patients 1, 3
This is the evidence-based standard because the precision of DXA measurements and the rate of bone turnover make more frequent scanning clinically unhelpful 1
Accelerated Monitoring (Every 1 Year)
High-risk patients requiring annual scans include: 1
- Patients initiating osteoporosis therapy
- Patients receiving glucocorticoid therapy (due to risk of substantial short-term decreases in mineralization)
- Cancer survivors on aromatase inhibitors, androgen deprivation therapy, or those with chemotherapy-induced ovarian failure
Critical pitfall: Never scan more frequently than annually—it provides no additional clinical benefit 1
Vertebral Fracture Assessment (VFA): An Often-Missed Opportunity
When to Perform VFA Simultaneously with DEXA
VFA should be performed concomitantly with DXA in patients with T-scores <-1.0 AND one or more of: 1
- Women ≥70 years or men ≥80 years
- Historical height loss >4 cm
- Self-reported but undocumented prior vertebral fracture
- Glucocorticoid therapy ≥5 mg prednisone equivalent daily for ≥3 months
Why VFA Matters
50% of fragility fractures occur in postmenopausal women with T-scores >-2.5 1. Identification of vertebral fractures can reclassify patients who would otherwise not qualify for treatment based solely on BMD measurements, directly impacting treatment decisions and preventing future fractures 1
Special Population Considerations
Premenopausal Women and Men <50 Years
- Use Z-scores (not T-scores) for interpretation, as WHO criteria do not apply to this population 1
- DEXA is only indicated if medical conditions or medications adversely affect bone density 1
Glucocorticoid Users
- Require one-year follow-up intervals due to risk of rapid bone loss 1
- Therapy should be considered at BMD T-score of <-1.5 (higher threshold than postmenopausal osteoporosis) because fractures occur at higher BMD levels in glucocorticoid-induced osteoporosis 2
Cancer Survivors
- Repeat DXA every 2 years or as clinically indicated for those on aromatase inhibitors, androgen deprivation therapy, or with chemotherapy-induced ovarian failure 1
Patients ≥65 Years Starting Treatment
Although baseline DEXA is useful for assessing response, it is not absolutely necessary to initiate bone protective therapy in those aged >65, since the vast majority will have a T-score of -1.5 or below 2
Critical Pitfalls to Avoid
Equipment and Technique Errors
- Never use peripheral DXA or quantitative ultrasound (QUS) for diagnosis in standard populations—these are screening tools only and cannot be interpreted using WHO criteria 1, 4
- Never compare scans from different DXA machines without cross-calibration 1