Is a medication holiday from alendronate (bisphosphonate) recommended before a repeating DEXA (Dual-Energy X-ray Absorptiometry) scan and if so, for how long?

Bisphosphonate Holiday Before DEXA Scan

A bisphosphonate holiday from alendronate is not recommended before repeating a DEXA scan, as the scan should be performed while on therapy to properly assess treatment response.

Rationale for Continuing Alendronate During DEXA

Bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DEXA) is the gold standard for monitoring response to osteoporosis treatment. The evidence indicates that DEXA scans should be performed while patients remain on bisphosphonate therapy for several reasons:

1. Monitoring Treatment Response: DEXA scans are specifically used to assess the effectiveness of ongoing treatment by measuring changes in bone density over time 1.

2. Timing of Follow-up Scans: Guidelines recommend follow-up DEXA scans after 1-2 years of therapy to assess response to treatment, without any recommendation for medication discontinuation before scanning 1.

3. Continuous Therapy Assessment: The American College of Physicians and American College of Oncology recommend BMD measurement with DEXA at baseline and after 1-2 years to assess response to ongoing treatment 1.

Recommended Monitoring Schedule

• Initial DEXA: Baseline measurement before starting bisphosphonate therapy
• Follow-up DEXA: After 1-2 years of therapy to assess treatment response 1
• Subsequent Monitoring:
  • For patients with normal BMD: Repeat DEXA after 2-3 years 2
  • For patients with rapid bone loss risk: Repeat DEXA within 1 year 2

Considerations for Bisphosphonate Holidays

While a holiday is not recommended before DEXA scanning, bisphosphonate holidays may be considered after 3-5 years of continuous therapy:

• Duration of Therapy: The American College of Physicians recommends a treatment duration of 5 years for most patients with osteoporosis 1
• Re-evaluation: All patients on bisphosphonate therapy should have the need for continued therapy re-evaluated periodically 3
• Discontinuation Criteria: Patients at low risk for fracture should be considered for drug discontinuation after 3-5 years of use 3
• Risk Re-assessment: Patients who discontinue therapy should have their fracture risk re-evaluated periodically 3

Important Caveats

1. Medication Adherence: Ensure proper adherence to alendronate therapy before the DEXA scan for accurate assessment of treatment response.

2. Supplementation: Continue calcium (1000-1500 mg/day) and vitamin D (400-800 IU/day) supplementation as recommended for patients with osteoporosis 2.

3. Timing Considerations: If planning a future bisphosphonate holiday, it's advisable to perform the DEXA scan while still on therapy to establish the maximum treatment effect before considering discontinuation.

4. Special Populations: For patients with specific conditions (e.g., liver disease, HIV infection), follow the specialized monitoring recommendations for those populations 2.

In summary, DEXA scans should be performed while continuing alendronate therapy to properly assess treatment response. The decision to take a bisphosphonate holiday should be made after reviewing DEXA results, not before obtaining them.