How often should a DEXA (Dual-Energy X-ray Absorptiometry) scan be repeated?

DEXA Scan Repeat Frequency

Repeat DEXA scans every 2 years for most patients, or annually for high-risk individuals, but never more frequently than once per year. 1, 2

Standard Repeat Intervals

Patients NOT Requiring Treatment

• Every 2 years if bone density does not demonstrate osteoporosis and FRAX calculation does not exceed treatment thresholds (10-year hip fracture risk <3% or major osteoporotic fracture risk <20%) 1
• Every 2-3 years for patients with normal BMD or mild osteopenia without additional risk factors 2, 3, 4
• Every 2-4 years for patients receiving ovarian hormone therapy 5

Patients ON Treatment for Osteoporosis

• Every 2 years once bone-modifying agents (bisphosphonates or denosumab) are initiated, or as clinically indicated 1, 3
• Every 1-2 years for patients undergoing bisphosphonate therapy 5

High-Risk Patients Requiring Annual Monitoring

Repeat DEXA annually (every 1 year) for patients with: 1, 2, 4

• Glucocorticoid therapy ≥5 mg prednisone equivalent per day for ≥3 months 1, 2, 4
• Significant osteopenia plus additional risk factors 1, 2
• Cancer-related bone loss risks:
  • Aromatase inhibitors for breast cancer 2, 4
  • Androgen deprivation therapy for prostate cancer 1, 4
  • GnRH agonists causing chemotherapy-induced ovarian failure 1, 2
• Advanced cirrhosis or awaiting transplantation 2
• Female athletes with Female Athlete Triad risk factors (history of eating disorders, amenorrhea, prior stress fractures) 2, 4

Critical Technical Requirements

Absolute Minimum Interval

BMD measurements should NEVER be conducted more frequently than annually because bone density changes occur slowly and measurement variability makes shorter intervals clinically meaningless. 1, 2, 3

Ensuring Accurate Comparisons

• Always use the same DXA machine for follow-up scans to enable precise comparisons 2, 3, 4
• Compare BMD values (g/cm²), not T-scores, between serial scans for more accurate assessment of changes 3, 4
• Changes must exceed the least significant change (LSC = 2.77 × precision error) to be clinically meaningful 3

Special Population Considerations

Spinal Cord Injury

• Initial DXA of total hip, proximal tibia, and distal femur as soon as medically stable 1
• Follow-up at 1-2 year intervals after minimum 12 months of therapy 1

Childhood/Young Adult Cancer Survivors

• If normal BMD at entry into long-term follow-up, repeat at age 25 years when peak bone mass is achieved, rather than at fixed intervals 2, 3

Patients with Degenerative Spine Disease

• Consider DXA distal forearm or QCT if advanced degenerative changes may spuriously elevate lumbar spine BMD 1
• Close inspection of images required to exclude falsely elevated measurements (>81% caused by degenerative disease) 1

Common Pitfalls to Avoid

• Scanning too frequently (<1 year intervals) provides no additional clinical value and wastes resources 2, 3
• Failing to recognize degenerative changes that falsely elevate spine BMD, particularly in older patients 1, 4
• Comparing T-scores instead of BMD values between scans reduces accuracy of change assessment 3, 4
• Using different DXA machines for follow-up compromises precision of serial measurements 2, 3, 4