When is a DEXA scan recommended?

DEXA Scan Recommendations

DEXA scans are recommended for all women aged 65 and older and men aged 70 and older, while younger individuals should undergo testing only if they have specific risk factors for bone loss. 1

Standard Screening Recommendations

Women

• All women aged 65 and older 2, 1
• Younger postmenopausal women (under 65) with risk factors 2
• Women whose 10-year fracture risk is equal to or greater than that of a 65-year-old white woman with no additional risk factors 2

Men

• All men aged 70 and older 1
• Men aged 50-69 with risk factors 2

Risk Factors That Warrant Earlier Screening

• Previous fragility fracture 1
• Low body weight (less than 127 lb/58 kg) 1
• Parental history of hip fracture 1
• Long-term glucocorticoid therapy (≥5 mg prednisone daily for ≥3 months) 2, 1
• Chronic inflammatory conditions (e.g., rheumatoid arthritis) 2, 1
• Conditions causing malabsorption or malnutrition 2, 1
• Untreated premature menopause or hypogonadism 1
• Organ transplantation 2, 1
• Prolonged immobilization 2, 1
• Endocrine disorders affecting bone (hyperparathyroidism, hyperthyroidism, Cushing syndrome) 2, 1
• Medications known to cause bone loss:
  • Anticonvulsants
  • Androgen deprivation therapy
  • Aromatase inhibitors
  • Chronic heparin 2, 1

Special Populations Requiring DEXA Scans

Cancer Survivors

• Postmenopausal breast cancer survivors should receive baseline DEXA scan 2
• Repeat DEXA scans every 2 years for:
  • Women taking aromatase inhibitors
  • Premenopausal women taking tamoxifen and/or GnRH agonists
  • Women with chemotherapy-induced premature menopause 2

HIV Patients

• DEXA scan for all HIV-infected postmenopausal women and men ≥50 years 2
• If results don't warrant treatment, repeat every 2-5 years depending on proximity to treatment thresholds 2

Screening Frequency

• Standard risk individuals: Every 2 years 2
• High-risk individuals: Every 1-2 years 2
• Patients on medications affecting bone density (e.g., glucocorticoids): Annual screening 2

Recommended Scan Sites

• For standard screening: Posteroanterior spine, total hip, femoral neck 2
• For adults ≥20 years: Weight-bearing sites (posteroanterior spine, total hip, femoral neck) 2
• For children, adolescents, and young women <20 years: Posteroanterior lumbar spine and whole body 2
• For patients with spinal deformities: Consider forearm DEXA scan in addition to hip scan 3

Clinical Pearls and Pitfalls

• BMD Z-scores (not T-scores) should be reported for children, adolescents, and premenopausal women 2
• Patients should be scanned on the same DXA scanner for follow-up as vendor differences in technologies prohibit direct comparison 2
• BMD values, not T-scores, should be compared between previous and current scans 2
• Scan intervals <1 year are discouraged 2
• For transgender individuals, Z-scores should be calculated using reference data conforming with the individual's gender identity 1
• In patients over 50 with advanced degenerative changes of the spine, these changes may spuriously elevate BMD values 1
• Weight alone is an unreliable predictor of low BMD, making comprehensive risk factor assessment essential 1

DEXA scanning remains the gold standard for bone density assessment, with CT-based Hounsfield unit measurements showing promise as an opportunistic screening tool during routine CT scans performed for other reasons 4.