Is the patient osteopenic or osteoporotic?

Distinguishing Osteopenia from Osteoporosis

The patient is classified as osteopenic if their T-score is between -1.0 and -2.5, and osteoporotic if their T-score is ≤ -2.5 at the lumbar spine, femoral neck, or total hip measured by DXA. 1, 2

Diagnostic Classification Based on T-Score

The World Health Organization (WHO) criteria provide clear thresholds for classification:

• Normal bone density: T-score ≥ -1.0 1, 2
• Osteopenia (low bone mass): T-score between -1.0 and -2.5 1, 2
• Osteoporosis: T-score ≤ -2.5 1, 2

The diagnostic classification is based on the lowest T-score at any of the recommended DXA measurement sites (lumbar spine, femoral neck, or total hip). 1

Critical Exception: Fragility Fracture Overrides T-Score

If the patient has sustained a fragility fracture (low-trauma fracture of the hip, spine, wrist, proximal humerus, or pelvis after age 50), they should be diagnosed with osteoporosis regardless of their T-score. 1, 2 This represents "severe" or "established" osteoporosis and warrants treatment without requiring BMD measurement. 1

Measurement Considerations

Standard DXA Measurement

• Measure BMD at the lumbar spine (L1-L4), femoral neck, and total hip 1, 2
• Use the young adult Caucasian female normative reference database (T-score) for both women and men 1

When to Use Z-Score Instead

In premenopausal women, men under age 50, and children, use Z-scores rather than T-scores for classification. 1, 2 A Z-score ≤ -2.0 indicates "bone mineral density below the expected range for age" in these populations. 1

QCT Alternative Thresholds

If quantitative CT (QCT) is used instead of DXA, the WHO T-score criteria do not apply. 1, 2 The ACR defines QCT thresholds as:

• Osteopenia: 80-120 mg/mL 1, 2
• Osteoporosis: <80 mg/mL 1, 2

Common Pitfalls to Avoid

Degenerative changes in the lumbar spine can artificially elevate BMD measurements, potentially masking true bone loss and misclassifying an osteoporotic patient as osteopenic. 3 In such cases, rely more heavily on hip measurements.

Do not diagnose osteoporosis based solely on radiographic appearance of osteopenia on plain X-rays—this requires formal DXA confirmation unless a fragility fracture is present. 1

Ensure repeat measurements are performed on the same DXA machine at the same facility using identical positioning to allow accurate comparison of absolute BMD values (g/cm²), not T-scores. 1