What is the interpretation and treatment for a patient with a DEXA (Dual-Energy X-ray Absorptiometry) scan showing osteopenia at the left femoral neck with a T-score of -1.2?

DEXA Interpretation and Management for Late 70s Patient

Interpretation: Low Bone Mass (Osteopenia) at Femoral Neck

This patient has osteopenia (low bone mass) based on the femoral neck T-score of -1.2, while the lumbar spine and total hip show normal bone density. 1

Key DEXA Findings:

• Lumbar spine (L1-L4): Normal BMD with T-score of -0.2 (≥ -1.0 indicates normal) 1
• Left femoral neck: Osteopenia with T-score of -1.2 (between -1.0 and -2.5 defines osteopenia) 1
• Left total hip: Normal BMD with T-score of -0.5 1
• Trabecular Bone Score: 1.416 (suggests good bone microarchitecture)
• Z-scores: All positive, indicating BMD is above average for age 1

The diagnostic classification is based on the lowest T-score at any recommended site, which in this case is the femoral neck at -1.2. 1

Treatment Decision Algorithm

Step 1: Assess for Prior Fragility Fractures

• If prior low-trauma fracture exists (hip, spine, forearm, humerus, pelvis, ribs, tibia): This automatically establishes osteoporosis diagnosis and warrants immediate pharmacologic treatment, regardless of T-score 1
• If no prior fracture: Proceed to Step 2

Step 2: Calculate 10-Year Fracture Risk Using FRAX

You must calculate FRAX score using the patient's:

• Age (late 70s)
• Sex
• BMI
• Prior fracture history
• Parental hip fracture history
• Current smoking status
• Glucocorticoid use
• Rheumatoid arthritis
• Secondary osteoporosis causes
• Alcohol consumption
• Femoral neck BMD 1, 2

Step 3: Treatment Thresholds

Pharmacologic treatment is warranted if: 2

• 10-year hip fracture probability > 5%, OR
• 10-year major osteoporotic fracture probability > 20%

For patients in their late 70s with osteopenia, FRAX scores frequently exceed these thresholds due to age alone, making treatment likely indicated. 3

Non-Pharmacologic Management (Universal for All Patients)

All patients with osteopenia should receive: 1

• Calcium supplementation: 1000-1200 mg daily 4
• Vitamin D supplementation: 800-1000 IU daily 1, 4
• Weight-bearing exercise: Regular physical activity 1
• Fall prevention strategies: Home safety assessment, balance training
• Smoking cessation if applicable
• Limit alcohol consumption to ≤2 drinks per day

Pharmacologic Treatment Options (If FRAX Thresholds Met)

First-Line: Oral Bisphosphonates 5

• Alendronate 70 mg once weekly, OR 6
• Risedronate 35 mg once weekly
• Must be taken on empty stomach with full glass of water, remain upright for 30 minutes 6

Alternative Options (If Bisphosphonates Contraindicated/Not Tolerated): 5

• Denosumab 60 mg subcutaneously every 6 months 7, 4
  • Critical warning: If denosumab is ever discontinued, MUST transition to bisphosphonate to prevent rebound bone loss and multiple vertebral fractures 7
• Selective estrogen receptor modulators (SERMs) in younger postmenopausal women 3

Monitoring Strategy

Follow-up DEXA Scanning: 4

• Repeat DEXA in 1-2 years on the same machine using the same protocol 1
• Compare absolute BMD values (g/cm²), NOT T-scores or Z-scores 1
• Changes must exceed the Least Significant Change (LSC) to be considered clinically meaningful 1
• Maximum acceptable LSC: 5.0% for total hip, 5.3% for lumbar spine 1

Vertebral Fracture Assessment (VFA):

Consider VFA imaging at baseline, especially given patient's age (late 70s), as: 1

• 38% of patients ≥65 years with vertebral fractures have osteoporosis by BMD criteria, but many have osteopenia or normal BMD 1
• Vertebral fractures are the strongest predictor of future fractures and automatically warrant treatment 4

Critical Pitfalls to Avoid

1. Do not ignore osteopenia in elderly patients: The majority of osteoporotic fractures occur in individuals with osteopenic T-scores, not osteoporosis 3

2. Do not treat based on T-score alone in osteopenia: Treatment requires either prior fracture OR high FRAX score 3

3. Do not use Z-scores for treatment decisions in adults: Z-scores are for identifying secondary causes; T-scores determine treatment 1

4. Do not assume lumbar spine is most important: In elderly patients, hip BMD (especially femoral neck) is the best predictor of hip fracture risk 2

5. Do not forget to screen for secondary causes of osteoporosis: Given the patient's age, evaluate for vitamin D deficiency, hyperparathyroidism, hyperthyroidism, celiac disease, multiple myeloma, and medication effects (especially glucocorticoids) 5, 2

Secondary Osteoporosis Screening

Order baseline laboratory tests: 5, 2

• Complete blood count
• Serum calcium, phosphate, alkaline phosphatase
• 25-hydroxyvitamin D level
• Thyroid-stimulating hormone
• Serum protein electrophoresis (if clinically indicated)
• Testosterone level (in men)