How often should a post‑menopausal woman or a man over 50 undergo dual‑energy X‑ray absorptiometry (DEXA) scanning, given risk factors such as osteopenia or osteoporosis, glucocorticoid therapy, recent fracture, or changes in bone‑active medication?

DEXA Scan Frequency Recommendations

Standard Monitoring Intervals

For most patients with osteoporosis or osteopenia, repeat DEXA scanning should occur every 2 years, as this interval provides sufficient time to detect clinically meaningful bone density changes while avoiding unnecessary radiation exposure and healthcare costs. 1, 2

Baseline Bone Density Determines Rescreening Intervals

For patients not on treatment, the interval can be stratified by baseline T-score:

• Normal BMD (T-score ≥ -1.0): Repeat in 15-17 years 3
• Mild osteopenia (T-score -1.0 to -1.5): Repeat in 15-17 years 3
• Moderate osteopenia (T-score -1.5 to -2.0): Repeat in 5 years 3
• Advanced osteopenia (T-score -2.0 to -2.5): Repeat in 1 year 3
• Osteoporosis (T-score ≤ -2.5): Initiate treatment and monitor every 2 years 1, 2

Patients on Osteoporosis Treatment

All patients receiving pharmacologic therapy should have repeat DEXA every 2 years, regardless of medication type (bisphosphonates, denosumab, etc.). 2 This applies equally to those starting new therapy and those already established on treatment. 2

The first follow-up scan after initiating therapy should typically occur at 1-2 years to assess early treatment response, then transition to 2-year intervals if stable. 1

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High-Risk Populations Requiring Annual Monitoring

Annual DEXA scanning (every 12 months) is indicated for patients with conditions causing accelerated bone loss:

• Glucocorticoid therapy >3 months: Annual scans until BMD stabilizes, then extend to 2-year intervals 1, 2, 4
• Aromatase inhibitor therapy (breast cancer): Annual scans during first 12-24 months when bone loss is most rapid 2, 4
• Androgen deprivation therapy (prostate cancer): Baseline at 6 months, then annually 2, 4
• Organ transplant recipients: Annual scans during first 6-12 months post-transplant 2
• Chronic renal failure, inflammatory arthritis, eating disorders, malabsorption syndromes, hypogonadism: Annual monitoring 1, 2
• Hyperparathyroidism: Every 1-2 years 1

Once bone density stabilizes in these high-risk patients, intervals can be extended to every 2 years. 1

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Immediate Repeat DEXA Indications

Perform an urgent repeat DEXA scan immediately when:

• New fragility fracture occurs at any major osteoporotic site (hip, spine, forearm, humerus, pelvis) 2
• New risk factors develop (e.g., starting glucocorticoids, diagnosis of hyperparathyroidism, malabsorption) 2
• Considering temporary cessation of bisphosphonate therapy (drug holiday) 2

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Critical Technical Requirements for Serial Monitoring

To ensure accurate longitudinal comparison:

• Use the identical DXA machine at the same facility for all follow-up scans 1, 2, 4
• Compare absolute BMD values (g/cm²), NOT T-scores or Z-scores, between serial measurements 1, 2, 4
• Replicate exact scan protocol: same software version, patient positioning, anatomical side (left vs. right hip), and acquisition mode 2
• Utilize the DXA system's "copy" function to automatically reproduce previous scan parameters 2
• Verify the facility has performed precision assessment to calculate the least significant change (LSC) threshold—typically ~2.8% for 1% precision error 2

Performing scans on different machines invalidates longitudinal comparison unless formal cross-calibration has been completed. 2

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Common Pitfalls and Caveats

Do Not Scan More Frequently Than Annually

Intervals <12 months are strongly discouraged because bone density changes too slowly to produce clinically meaningful differences over shorter periods. 1, 4 This wastes resources without improving clinical decision-making. 2

Beware of Lumbar Spine Artifacts

Degenerative changes (osteophytes, facet arthritis, spondylosis, aortic calcification) falsely elevate lumbar spine BMD values, potentially masking true bone loss. 1, 2, 4 Always inspect images for artifacts. When more than 2 lumbar vertebrae are compromised, substitute measurements from the contralateral hip or distal one-third radius. 2

Special Populations

• Postmenopausal women <65 years with risk factors (early menopause, oophorectomy, family history, low body weight <70 kg, prior fracture): Baseline DEXA is indicated, then follow standard monitoring intervals 1, 5
• All women ≥65 years: Baseline DEXA recommended regardless of risk factors 1, 4
• Men ≥50 years: Use T-scores for interpretation; men <50 years require Z-scores 4
• Men account for 24% of hip fractures but only 10% of DEXA scans—do not overlook male patients, especially after fracture 6

Post-Fracture Management Gap

Only 19% of patients >65 years undergo DEXA within one year after fracture, and only 41% receive treatment. 6 This represents a critical care gap—always obtain DEXA and initiate appropriate therapy after any fragility fracture. 2

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Algorithm Summary

1. Baseline DEXA: All women ≥65, postmenopausal women <65 with risk factors, men ≥50 with risk factors 1, 4

2. Stratify by baseline T-score and risk factors:

   • Normal/mild osteopenia + no risk factors → 15-17 years 3
   • Moderate osteopenia → 5 years 3
   • Advanced osteopenia → 1 year 3
   • Osteoporosis or on treatment → 2 years 1, 2
   • High-risk conditions (glucocorticoids, cancer therapy, transplant) → 1 year until stable 1, 2

3. After new fracture or new risk factors → Immediate repeat 2

4. Always use same machine and compare BMD values (g/cm²), not T-scores 1, 2, 4