When is a DEXA (Dual-Energy X-ray Absorptiometry) scan recommended for individuals under 65 years of age?

DEXA Scan Recommendations for Individuals Under 65 Years of Age

DEXA screening is NOT recommended for routine use in women younger than 65 years or men younger than 70 years without documented risk factors, but should be performed earlier in the presence of specific high-risk conditions. 1, 2, 3

Standard Age-Based Screening Thresholds

• Women aged 65 years and older should undergo routine DEXA screening regardless of risk factors 1, 2, 3
• Men aged 70 years and older should undergo routine DEXA screening regardless of risk factors 1, 2, 3
• Screening below these age thresholds without risk factors exposes patients to unnecessary radiation and costs without clinical benefit 2

High-Risk Conditions Warranting Earlier Screening (Under Age 65)

Medical Conditions:

• Previous fragility fracture at any age (strongest predictor of future fractures, increasing risk approximately 2-fold) 1, 3, 4
• Long-term glucocorticoid therapy (fractures occur at higher BMD levels than postmenopausal osteoporosis; consider treatment at T-score <-1.5) 1, 2, 3, 5
• Hyperparathyroidism or hypogonadism 1, 3
• Chronic inflammatory diseases (including rheumatoid arthritis) 1, 2
• Chronic renal failure 2
• Eating disorders 2
• Organ transplantation 2
• Spinal cord injury (screen as soon as medically stable) 1, 3

Medication-Related Risk Factors:

• Androgen deprivation therapy for prostate cancer 6, 1, 3
• Anticonvulsant drugs 2
• Aromatase inhibitor therapy 2
• Chronic heparin therapy 2

Postmenopausal Women Under 65 Specific Criteria:

• Body weight less than 127 pounds 2
• Parental history of hip fracture 2
• Early menopause or surgically/chemotherapeutically induced castration 2, 3
• 10-year major osteoporotic fracture risk ≥9.3% as calculated by FRAX 2, 3
• Chronic alcoholism (causes bone loss through impaired calcium absorption, vitamin D deficiency, direct toxic effects on osteoblasts, and increased fall risk) 3

Additional Risk Factors:

• Prolonged immobilization 2
• Low body mass index (<20-25 kg/m²) 6
• Weight loss >10% compared with usual adult weight 6
• Physical inactivity 6

Critical Algorithm for Men Under 70

• Men account for 24% of all hip fractures and 21% of all wrist fractures, yet receive only 10% of BMD tests 4
• Screen men under 70 with: hypogonadism, androgen deprivation therapy, glucocorticoid use, previous fragility fracture, spinal cord injury, or chronic alcoholism 6, 1, 2, 3
• By age 65 years, at least 6% of men have DXA-determined osteoporosis, making risk assessment before this age reasonable 6

Screening Intervals After Initial DEXA

• Normal bone density or mild osteopenia: repeat in 2-3 years 1, 2
• Osteoporosis or on treatment: repeat in 1-2 years to monitor treatment effectiveness 1, 2
• High risk for accelerated bone loss (glucocorticoid therapy, spinal cord injury): repeat in 1-2 years 1, 2
• Never repeat DEXA at intervals less than 1 year under any circumstances 1, 2
• For individuals with normal baseline BMD (T-score ≥-1) and bone loss rate ≤1% per year, serial measurements every 24 months are not necessary; change in BMD is unlikely to exceed least significant change in less than 3 years 4

Technical Considerations

• Scan both lumbar spine and bilateral hips when feasible 2
• Use T-scores for all postmenopausal women regardless of age 2
• Use Z-scores for premenopausal women and men under 50 2
• Consider Vertebral Fracture Assessment (VFA) during the same session for patients with T-score <-1.0 and additional risk factors (women ≥70 years, men ≥80 years, historical height loss >4 cm, prior vertebral fracture, or glucocorticoid therapy ≥5 mg prednisone daily for ≥3 months) 1

Common Pitfalls to Avoid

• Do not delay screening in patients with chronic alcoholism, early menopause, or glucocorticoid use until age 65—these conditions justify earlier screening regardless of age 2, 3
• Do not screen women under 65 or men under 70 without documented risk factors 2, 3
• Do not repeat DEXA scans more frequently than every 2 years in patients with normal BMD, as testing precision limitations make shorter intervals unreliable 1, 2
• Do not assume obesity provides adequate protection against osteoporosis when other major risk factors are present (obesity is actually protective, but should not override other high-risk conditions) 3
• Do not overlook men after fractures—rates of BMD testing and treatment in men after fracture are only half those in women 4
• Low body weight alone is unreliable for identifying osteoporosis and should not be the sole screening criterion 7

Post-Fracture Management Gap

• Only 19% of people age >65 years undergo BMD testing and 41% receive osteoporosis treatment during the year following a fracture 4
• Any prevalent fracture increases relative risk for future fractures by approximately 2-fold or more, warranting immediate DEXA assessment 4