At what age should a postmenopausal woman with a significant smoking history and possible history of hormone replacement therapy (HRT) start getting Dual-Energy X-ray Absorptiometry (DEXA) screenings for osteoporosis?

DEXA Screening for Osteoporosis in Postmenopausal Women

For a postmenopausal woman with significant smoking history, begin DEXA screening now if she is age 65 or older, or immediately at any age under 65 if her 10-year fracture risk equals or exceeds 9.3% (equivalent to a 65-year-old white woman without risk factors). 1

Age-Based Screening Thresholds

Women Age 65 and Older

• All women age 65 and older should undergo routine DEXA screening of the hip and lumbar spine, regardless of other risk factors. 1, 2, 3
• This is a Grade B recommendation with strong evidence that screening and treatment reduce fracture risk and associated morbidity and mortality. 1, 3

Women Under Age 65

• Screen postmenopausal women younger than 65 years if their fracture risk equals or exceeds that of a 65-year-old white woman without additional risk factors (9.3% 10-year fracture risk). 1, 2
• Smoking is a major risk factor that significantly increases fracture risk, particularly in women. 1, 4

Risk Assessment Algorithm for Women Under 65

Step 1: Identify Major Risk Factors

Key risk factors beyond postmenopausal status include: 1

• Cigarette smoking (your patient has this)
• Low body weight (< 70 kg or BMI < 21 kg/m²)
• Parental history of hip fracture
• Excess alcohol consumption (daily use)
• History of hormone replacement therapy (HRT) discontinuation

Step 2: Calculate FRAX Score

• Use the FRAX tool to estimate 10-year fracture risk using age, BMI, smoking status, and other clinical factors. 1
• The tool does not require prior DEXA results to calculate risk. 1
• A 10-year fracture risk ≥9.3% warrants DEXA screening. 1

Step 3: Examples of High-Risk Profiles Requiring Screening

Women under 65 who meet the 9.3% threshold include: 1

• Age 50: current smoker with BMI < 21 kg/m², daily alcohol use, and parental fracture history
• Age 55: parental fracture history alone
• Age 60: BMI < 21 kg/m² and daily alcohol use
• Age 60: current smoker with daily alcohol use

Screening Methodology

Preferred Test

• DXA of the hip and lumbar spine is the gold standard screening test. 1, 2, 3
• Bone density measured at the femoral neck by DXA is the best predictor of hip fracture. 1, 3
• DXA uses low radiation doses and correlates with bone strength and clinical fracture outcomes. 1

Diagnostic Threshold

• Osteoporosis is defined as a T-score ≤ -2.5 at the hip or lumbar spine. 1

Screening Intervals

• Minimum 2 years between repeat DEXA scans is needed to reliably measure changes in bone mineral density. 1, 2, 3
• Longer intervals (every 2-3 years for normal BMD) may be adequate for repeated screening. 2, 3
• Women with normal BMD at age 65 may not transition to osteoporosis for almost 17 years. 2
• Higher-risk women (lower baseline BMD, additional risk factors) benefit from more frequent screening. 1, 3

Critical Considerations for Your Patient

Smoking as a Risk Factor

• Smoking risk is proportionately higher in women than men, making cessation particularly important. 4
• Smoking cessation should be strongly encouraged regardless of age, with benefits seen within 6 months. 4
• Use the "Five As" approach: Ask, Advise, Assess, Assist, Arrange follow-up. 4

HRT History

• Discontinuation of HRT increases fracture risk and should be factored into screening decisions. 1
• Low weight and no current estrogen therapy are incorporated into risk assessment tools. 1

Common Pitfalls to Avoid

• Do not wait until age 65 to screen if significant risk factors are present. 1 The USPSTF 9.3% threshold has low sensitivity (24-37%) for detecting osteoporosis in younger women, meaning many cases are missed if screening is delayed. 5
• Do not use BMI alone for screening decisions, though BMI < 28 kg/m² has reasonable sensitivity (95%) for detecting osteoporosis in postmenopausal women ages 50-64. 6
• Do not repeat DEXA scans more frequently than every 2 years unless clinically indicated, as precision limitations prevent reliable measurement of change. 1, 2
• Do not overlook that advancing age is a stronger determinant of fracture risk than bone density alone due to declining bone quality and increased fall risk. 1

Practical Implementation

For your specific patient with smoking history and possible HRT use:

1. Calculate her FRAX score immediately using current age, BMI, smoking status, and other risk factors. 1
2. If FRAX score ≥9.3% or if she is age 65+, order DEXA of hip and lumbar spine now. 1, 2
3. Initiate smoking cessation counseling with pharmacological support if needed. 4
4. Ensure adequate calcium (1000-1200 mg daily) and vitamin D (800-1000 IU daily) intake. 3
5. Implement fall prevention strategies and weight-bearing exercise. 4, 3