DEXA DEXA Pharmacology & Osteoporosis Treatment Monitoring 2 — Questions and Answers
Question 1: A patient taking long-term glucocorticoids (prednisone ≥5 mg/day for ≥3 months) presents for a DEXA scan. Why is this clinically important?
- Glucocorticoids cause glucocorticoid-induced osteoporosis (GIO), a major secondary cause of bone loss (Correct answer)
- Glucocorticoids increase bone density and DEXA is used to confirm this
- Glucocorticoids only affect soft tissue, not bone
- Steroids cause artifacts on DEXA images that must be corrected
Correct answer: Glucocorticoids cause glucocorticoid-induced osteoporosis (GIO), a major secondary cause of bone loss
Glucocorticoid-induced osteoporosis is the most common secondary cause of osteoporosis, and baseline and monitoring DEXA scans are recommended for these patients.
Question 2: Which FRAX input variable directly represents the skeletal impact of chronic glucocorticoid use?
- Secondary osteoporosis checkbox and glucocorticoid input field (Correct answer)
- Body mass index (BMI)
- Femoral neck BMD T-score only
- Spine fracture history field
Correct answer: Secondary osteoporosis checkbox and glucocorticoid input field
FRAX includes a secondary osteoporosis field and a separate glucocorticoid input that adjusts fracture probability upward for chronic steroid users.
Question 3: What is the recommended DEXA monitoring interval for patients on long-term glucocorticoid therapy?
- Every 1–2 years for patients on ongoing glucocorticoid therapy (Correct answer)
- Every 5 years
- Only at initiation of steroid therapy
- Monthly scans during the first year
Correct answer: Every 1–2 years for patients on ongoing glucocorticoid therapy
ACR and ISCD recommend monitoring DEXA every 1–2 years in patients on ongoing glucocorticoid therapy due to the risk of rapid bone loss.
Question 4: A DEXA report shows a patient's hip BMD increased by 3% after 2 years of denosumab therapy, but the result is below the LSC. How should this be interpreted?
- The change is not statistically significant and may be within measurement error (Correct answer)
- The treatment is definitely effective and the dose should be reduced
- The treatment is ineffective and must be stopped immediately
- The hip site should be excluded from future monitoring
Correct answer: The change is not statistically significant and may be within measurement error
A BMD change below the LSC cannot be distinguished from measurement variability and should not be used alone to make treatment decisions.
Question 5: Which lab values are most important to review before initiating bisphosphonate therapy in a patient with low bone density?
- Serum creatinine/eGFR (renal function) and 25-hydroxyvitamin D (Correct answer)
- Fasting glucose and hemoglobin A1c
- Thyroid-stimulating hormone (TSH) only
- CBC and platelet count
Correct answer: Serum creatinine/eGFR (renal function) and 25-hydroxyvitamin D
Bisphosphonates are contraindicated in severe renal impairment (eGFR <30–35), and vitamin D deficiency must be corrected before therapy to avoid hypocalcemia.
Question 6: A patient on denosumab discontinues therapy without transitioning to a bisphosphonate. What bone density outcome is expected?
- Rapid rebound bone loss (rebound osteoporosis) with increased fracture risk (Correct answer)
- Bone density stabilizes at the level achieved on denosumab
- Gradual slow decline over 5 years
- No change in bone density after discontinuation
Correct answer: Rapid rebound bone loss (rebound osteoporosis) with increased fracture risk
Abrupt denosumab discontinuation causes rapid rebound bone loss, potentially below pre-treatment levels, with significantly elevated vertebral fracture risk.
DEXA DEXA Pharmacology & Osteoporosis Treatment Monitoring 2
A patient taking long-term glucocorticoids (prednisone ≥5 mg/day for ≥3 months) presents for a DEXA scan.
Why is this clinically important?