When is a Dual-Energy X-ray Absorptiometry (DEXA) scan recommended for patients with risk factors for osteoporosis, such as postmenopausal women or older adults with a history of fractures or low bone mass index?

DEXA Scan Recommendations for Osteoporosis Screening

All women aged 65 years and older and all men aged 70 years and older should undergo DEXA screening of the lumbar spine and bilateral hips regardless of risk factors. 1, 2, 3

Standard Age-Based Screening

• Women ≥65 years: Routine DEXA screening is indicated without requiring additional risk factors 4, 1, 2
• Men ≥70 years: Routine DEXA screening is indicated without requiring additional risk factors 1, 2, 3
• Women <65 years and men <70 years without risk factors: Screening is NOT recommended 1, 2, 3

High-Risk Groups Requiring Earlier Screening (Any Age)

Medical Conditions:

• Previous fragility fracture (wrist, hip, spine, or proximal humerus with minimal trauma) 4, 1, 2
• Glucocorticoid therapy for >3 months or expected duration >3 months 4, 1
• Chronic alcoholism or established cirrhosis 4, 2
• Hyperparathyroidism, hyperthyroidism, or Cushing syndrome 4
• Hypogonadism in men >18 years or surgically/chemotherapeutically induced castration 4
• Androgen deprivation therapy for prostate cancer 1, 2, 3
• Chronic renal failure, rheumatoid arthritis, or eating disorders 3
• Malabsorption syndromes, sprue, or vitamin D deficiency 4
• Gastric bypass surgery for obesity 4
• Spinal cord injury (as soon as medically stable) 1, 3

Medication-Related Risk Factors:

• Anticonvulsant drugs 4, 1
• Aromatase inhibitor therapy 4, 3
• Chronic heparin therapy 4, 3

Postmenopausal Women <65 Years:

• Body weight <127 pounds 3
• Parental history of hip fracture 3
• Early menopause 3
• 10-year major osteoporotic fracture risk ≥9.3% by FRAX 1, 2, 3

Scanning Technique and Interpretation

Standard Protocol:

• Scan both lumbar spine (L1-L4) and bilateral hips in a single session 4, 3
• Use T-scores for all postmenopausal women regardless of age 3
• Use Z-scores (not T-scores) for premenopausal women and men <50 years 4, 3

WHO Diagnostic Criteria (T-scores):

• Normal: T-score >-1.0 4
• Osteopenia: T-score -1.0 to -2.4 4
• Osteoporosis: T-score ≤-2.5 4

Vertebral Fracture Assessment (VFA):

• Perform VFA during the same DEXA session for patients with T-score <-1.0 AND one or more of: 4, 1
  • Women ≥70 years or men ≥80 years
  • Historical height loss >4 cm (>1.5 inches)
  • Self-reported but undocumented prior vertebral fracture
  • Glucocorticoid therapy ≥5 mg prednisone daily for ≥3 months

Follow-Up Screening Intervals

Normal Bone Density or Mild Osteopenia:

• Repeat DEXA in 2-3 years 1, 3
• For individuals with normal baseline BMD (T-score ≥-1.0) and no risk factors, repeat testing may not be necessary for up to 16 years 1

Osteoporosis or On Treatment:

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

High Risk for Accelerated Bone Loss:

• Repeat DEXA in 1-2 years (glucocorticoid therapy, spinal cord injury) 4, 1, 3

Critical Timing Rule:

• Never repeat DEXA at intervals <1 year under any circumstances 1
• Minimum 2-year interval needed to reliably measure biological change in BMD due to testing precision limitations 1

Special Considerations for Degenerative Spine Disease

When Advanced Degenerative Changes Present:

• DXA may spuriously elevate lumbar spine BMD values due to spondylosis and facet osteoarthritis 4
• Exclude no more than 2 vertebral levels from L1-L4 calculation; if >2 levels affected, exclude entire spine 4
• Scan contralateral hip if spine excluded 4
• Consider QCT as alternative, which selectively samples cancellous bone and avoids cortical/posterior element artifacts 4

Critical Pitfalls to Avoid

• Do not delay screening in patients with chronic alcoholism, glucocorticoid use, or previous fracture until standard age thresholds—these conditions justify immediate screening regardless of age 2, 3
• Do not screen women <65 or men <70 without documented risk factors—this exposes patients to unnecessary radiation and costs without clinical benefit 3
• Do not repeat DEXA more frequently than every 2 years in patients with normal BMD—the change in BMD will not exceed the least significant change threshold and cannot reliably predict treatment need 1
• Do not assume obesity protects against osteoporosis when other major risk factors are present—obesity is not an indication for screening but does not negate other risk factors 2
• Do not overlook men after fracture—men account for 24% of hip fractures but only 10% of DEXA scans, and their post-fracture screening/treatment rates are half those of women 5
• Do not fail to screen and treat after age 65 fracture—only 19% of individuals >65 years undergo BMD testing and 41% receive treatment in the year following fracture 5