When is a bone density exam recommended?

Bone Density Exam Recommendations

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

Universal Screening Ages

• Women ≥65 years: Routine DEXA screening is recommended universally, without requiring additional risk factor assessment 1, 2, 3
• Men ≥70 years: Routine DEXA screening is recommended at this age threshold 1, 2, 4
• No routine screening: Women <65 years and men <70 years without risk factors should not undergo routine screening 2, 4

Earlier Screening for High-Risk Individuals

Postmenopausal women younger than 65 years should undergo DEXA screening if they have a 10-year major osteoporotic fracture risk ≥9.3% (equivalent to a 65-year-old white woman with no additional risk factors) as calculated by FRAX or other validated tools. 1, 2, 3

Specific High-Risk Conditions Requiring Immediate Screening (Any Age):

• Previous fragility fracture at any skeletal site with minimal or no trauma 1, 2, 4
• Long-term glucocorticoid therapy (≥5 mg prednisone daily for ≥3 months) 1, 2, 4
• Medical conditions causing bone loss: hyperparathyroidism, hypogonadism, chronic inflammatory diseases 2, 4
• Medications associated with bone loss: aromatase inhibitors, androgen deprivation therapy 1, 2, 4
• Spinal cord injuries: screen as soon as medically stable 2, 4

Additional Risk Factors for Earlier Screening in Postmenopausal Women <65 Years:

• Low body weight (<70 kg or <127 lb) - this is the single best predictor of low bone mineral density 3
• Maternal hip fracture after age 50 1
• History of amenorrhea >1 year before age 42 1
• Current cigarette smoking 1
• Loss of height or thoracic kyphosis 1
• Estrogen deficiency 1

Optimal Testing Sites and Methodology

DXA of the lumbar spine and proximal femur (hip) is the gold standard for osteoporosis screening. 1, 3

• Bone density measured at the femoral neck is the best predictor of hip fracture 3
• Standard DXA measures two sites: lumbar spine (L1-L4) and hip (femoral neck and total hip) 1
• Alternative technologies (quantitative ultrasonography, peripheral DXA) can predict fracture risk but should not be used for diagnosis or monitoring 3

Rescreening Intervals

The frequency of repeat DEXA screening should be based on initial results and risk profile, not a fixed universal interval. 1, 2, 4

Evidence-Based Rescreening Schedule:

• Normal bone density or mild osteopenia: Repeat in 2-3 years 2, 4
• Osteoporosis or on treatment: Repeat in 1-2 years to monitor treatment effectiveness 2, 4
• High-risk for accelerated bone loss (e.g., glucocorticoid therapy): Repeat in 1-2 years 4
• Minimum interval: At least 2 years between scans is needed to reliably detect change due to testing precision limitations 1, 3

Important Caveat on Rescreening:

A prospective study found that in women ≥65 years with normal baseline BMD, neither repeated measurement nor the change in BMD after 8 years was more predictive of fracture than the original measurement 4. For women with normal baseline BMD, rescreening intervals can be extended to 4-8 years without loss of fracture prediction accuracy. 4

Special Populations

• HIV-infected individuals: Postmenopausal women and men ≥50 years should undergo DEXA; if normal, repeat every 2-5 years depending on proximity to treatment thresholds 2
• Cancer survivors: Women ≥65 years should receive universal screening; younger patients require risk-based assessment incorporating cancer treatments that cause bone loss 1
• Transgender individuals: Calculate Z-scores using reference data conforming to gender identity 2, 4

Common Pitfalls to Avoid

• Do not screen too frequently: Intervals <2 years provide no additional clinical benefit and expose patients to unnecessary radiation and costs 4
• Do not rely solely on T-scores: Combine BMD results with clinical risk factors (age, prior fracture, family history) for accurate fracture risk assessment 1
• African-American women have higher average BMD than white women at the same age and may be less likely to benefit from screening 3
• Vertebral fractures may be present even with BMD above treatment thresholds; consider vertebral fracture assessment (VFA) in high-risk patients 3, 4