DEXA Data Interpretation & Reporting 2 — Questions and Answers
Question 1: A postmenopausal woman's lumbar spine T-score is -2.7. According to WHO criteria, how should this be classified?
- Normal bone density
- Osteopenia
- Osteoporosis (Correct answer)
- Severe osteoporosis
Correct answer: Osteoporosis
A T-score of -2.5 or below is classified as osteoporosis by WHO criteria.
Question 2: On a DEXA report, the Z-score compares bone density to which reference population?
- Young adult peak bone mass
- Age-matched and sex-matched peers (Correct answer)
- Postmenopausal women only
- The same patient's prior scan
Correct answer: Age-matched and sex-matched peers
The Z-score compares a patient's BMD to age-matched and sex-matched reference norms.
Question 3: A DEXA report shows a BMD of 0.842 g/cm² at the femoral neck with a T-score of -1.8. What is the most appropriate classification?
- Normal
- Osteopenia (Correct answer)
- Osteoporosis
- Severe osteoporosis
Correct answer: Osteopenia
T-scores between -1.0 and -2.5 are classified as osteopenia (low bone mass).
Question 4: When reporting total hip BMD, which sub-regions are typically averaged together?
- Femoral neck and Ward's triangle
- Femoral neck, trochanter, and intertrochanteric region (Correct answer)
- Greater trochanter and lesser trochanter only
- Femoral neck and proximal shaft
Correct answer: Femoral neck, trochanter, and intertrochanteric region
Total hip BMD is derived from averaging the femoral neck, trochanter, and intertrochanteric sub-regions.
Question 5: A patient's follow-up lumbar spine BMD increased from 0.910 to 0.932 g/cm². The facility's LSC is 0.030 g/cm². How should this change be reported?
- Significant increase in BMD
- No significant change — within measurement error (Correct answer)
- Significant decrease in BMD
- Cannot be determined without T-scores
Correct answer: No significant change — within measurement error
A change of 0.022 g/cm² is below the LSC of 0.030 g/cm², so it falls within measurement error and is not statistically significant.
Question 6: Which DEXA skeletal site is considered the gold standard for diagnosing osteoporosis in postmenopausal women per NOF guidelines?
- Distal radius (33%)
- Calcaneus
- Lumbar spine (L1–L4) or total hip (Correct answer)
- Whole body
Correct answer: Lumbar spine (L1–L4) or total hip
NOF guidelines designate the lumbar spine (L1–L4) and proximal femur (total hip/femoral neck) as the primary diagnostic sites.
Question 7: A DEXA report includes a FRAX® score. What does this score estimate?
- Bone mineral content in grams
- 10-year probability of major osteoporotic fracture (Correct answer)
- Rate of bone loss per year
- Trabecular bone score
Correct answer: 10-year probability of major osteoporotic fracture
FRAX® calculates the 10-year probability of a major osteoporotic or hip fracture using BMD and clinical risk factors.
DEXA Data Interpretation & Reporting 2
A postmenopausal woman's lumbar spine T-score is -2.7.
According to WHO criteria, how should this be classified?