At what age and how often should a Dual-Energy X-ray Absorptiometry (DEXA) scan be ordered and repeated?

DEXA Scan Ordering Guidelines: Age and Repeat Intervals

Initial Screening Age

All women should undergo routine DEXA screening starting at age 65 years, and all men should begin routine screening at age 70 years, regardless of risk factors. 1, 2, 3

Earlier Screening for High-Risk Individuals

Screen postmenopausal women younger than 65 years and men younger than 70 years if any of the following risk factors are present:

• Previous fragility fracture (at any age) 2, 3
• Long-term glucocorticoid therapy (≥5 mg prednisone daily for ≥3 months) 2, 3
• Medical conditions associated with bone loss: hyperparathyroidism, hypogonadism, chronic inflammatory diseases 2, 3
• Medications associated with bone loss (aromatase inhibitors, androgen deprivation therapy) 2, 3
• Early menopause or oophorectomy before natural menopause 4
• Spinal cord injury (as soon as medically stable) 2, 3
• 10-year major osteoporotic fracture risk ≥9.3% as calculated by FRAX 2, 3

The American Academy of Family Physicians explicitly recommends against routine screening in women younger than 65 years and men younger than 70 years without these risk factors. 2, 3

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Repeat Screening Intervals

For Individuals with Normal Bone Density or Mild Osteopenia

Repeat DEXA in 2-3 years for those with normal BMD or mild osteopenia. 2, 3 However, the evidence supports much longer intervals in specific circumstances:

• Women with normal baseline BMD: Repeat screening can be extended to 4-8 years, as neither repeated BMD measurement nor the change in BMD after 8 years was more predictive of fracture risk than the original measurement. 2
• Women with baseline T-score in the -1.50 to -1.99 range: Transition to osteoporosis occurs over approximately 5 years. 2
• Women with truly normal BMD: Transition to osteoporosis takes approximately 17 years. 2

BMD measurements do not need to be repeated routinely in patients with osteopenia unless the baseline T-score is < -2.0 or new risk factors develop. 2

For Individuals with Osteoporosis or on Treatment

Repeat DEXA in 1-2 years to monitor treatment effectiveness. 2, 3, 4

For High-Risk Accelerated Bone Loss

Repeat DEXA in 1-2 years for patients at high risk for accelerated bone loss, including:

• Those on glucocorticoid therapy 2
• Women who underwent oophorectomy before natural menopause 4
• Individuals with spinal cord injuries 2, 3

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Critical Pitfalls to Avoid

• Never repeat DEXA scans more frequently than every 2 years in patients with normal BMD, as testing precision limitations make shorter intervals clinically meaningless and expose patients to unnecessary radiation and costs. 2
• Scan intervals less than 1 year are not recommended under any circumstances. 2
• Do not wait until age 65 to screen when significant risk factors like early menopause are present. 4
• Assess for new risk factors at each clinical encounter, including development of conditions associated with bone loss, new medications affecting bone metabolism, and height loss >4 cm or kyphosis. 2
• Be aware that different DXA machines may exhibit measurement variation unless cross-calibration has been performed. 2

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Algorithmic Approach to Screening Intervals

1. At initial screening: Assess baseline T-score and risk factors 2
2. If T-score is normal and no risk factors: Consider repeat in 4-8 years 2
3. If T-score is -1.0 to -1.49 and no risk factors: Repeat in 2-3 years 2
4. If T-score is -1.50 to -1.99: Repeat in 2 years (transition to osteoporosis occurs over ~5 years) 2
5. If T-score is < -2.0 or osteoporosis diagnosed: Initiate treatment and repeat in 1-2 years 2, 3
6. If new risk factors develop: Shorten interval to 1-2 years regardless of baseline BMD 2

A minimum of 2 years is required to reliably measure a change in BMD due to testing precision limitations. 2