For a patient with osteoporosis who completed 5 years of alendronate with benefit and is now 2 years into a bisphosphonate holiday, a DXA scan is recommended now or within the next year, as guidelines recommend reassessing fracture risk and BMD every 2 to 3 years during a drug holiday.[1][2]
DXA Monitoring During a Bisphosphonate Holiday
The Endocrine Society guideline recommends reassessing fracture risk at 2- to 4-year intervals once a bisphosphonate holiday is initiated.[1] The Bone Health and Osteoporosis Foundation similarly recommends reassessing fracture risk and BMD every 2 to 3 years during a holiday.[2] The AACE/ACE guideline recommends monitoring BMD every 1 to 2 years until stable.[3][2] Given that this patient is already 2 years off therapy, obtaining a DXA now is reasonable and aligns with the most commonly cited interval.
What to Do With the Results
The decision to restart therapy should be individualized based on:
- Significant BMD decline beyond the least significant change (LSC) of the DXA machine[3]
- An intervening fracture[1][4]
- Bone turnover markers (BTMs) returning to pretreatment levels (optional adjunct)[1][4]
- Return to a FRAX-based intervention threshold[1]
Data from the FLEX trial show that after stopping alendronate, approximately 50–75% of BMD gains are lost over 5 years, though BMD remains above pretreatment levels.[1] A predictive model from FLEX data suggests that women with total hip T-score better than −1.9 at the time of discontinuation have less than a 20% probability of crossing a −2.5 retreatment threshold within 5 years, meaning early repeat DXA may be less informative in those with higher BMD at the start of the holiday.[5]
Maximum Holiday Duration and Retreatment
The bisphosphonate holiday should generally not exceed 5 years for oral bisphosphonates, though this may be individualized.[1] If fracture risk remains or returns to high (T-score ≤ −2.5, prior hip/spine fracture, or elevated FRAX), treatment should be reinitiated or an alternative agent considered.[3][4]
References
- Pharmacological Management of Osteoporosis in Postmenopausal Women: An Endocrine Society* Clinical Practice Guideline. Eastell R, Rosen CJ, Black DM, et al. The Journal of Clinical Endocrinology and Metabolism. 2019;104(5):1595-1622. doi:10.1210/jc.2019-00221.
- Osteoporosis. Morin SN, Leslie WD, Schousboe JT. JAMA. 2025;334(10):894-907. doi:10.1001/jama.2025.6003.
- American Association of Clinical Endocrinologists/American College of Endocrinology Clinical Practice Guidelines for the Diagnosis and Treatment of Postmenopausal Osteoporosis-2020 Update. Camacho PM, Petak SM, Binkley N, et al. Endocrine Practice. 2020;26(Suppl 1):1-46. doi:10.4158/GL-2020-0524SUPPL.
- Postmenopausal Osteoporosis. Walker MD, Shane E. The New England Journal of Medicine. 2023;389(21):1979-1991. doi:10.1056/NEJMcp2307353.
- A Model of BMD Changes After Alendronate Discontinuation to Guide Postalendronate BMD Monitoring. McNabb B, Vittinghoff E, Eastell R, et al. The Journal of Clinical Endocrinology and Metabolism. 2014;99(11):4094-100. doi:10.1210/jc.2014-1193.