Multiple severe vertebral fractures during the 3-month period following a missed dose of denosumab in a postmenopausal woman with osteoporosis previously treated with alendronate .

Denosumab is a monoclonal antibody that decreases bone resorption and increases bone mass and strength in trabecular and cortical bone leading to a reduction in fracture in women and men. Its effects are reversed after discontinuation. Recently, there has been concern about the discontinuation of denosumab and the increased risk of multiple vertebral fractures that would be associated with rapid bone loss due to high bone turnover and consequent increase in markers of bone remodeling, far above the baseline values. Some case reports have demonstrated the occurrence of more than two fractures within a period of 8 - 16 months after the drug's discontinuation. A 56-year-old female presented with multiple vertebral fractures in a short period of time after denosumab withdrawal. She took alendronate for 12 years since the occurrence of a rib fracture (from the age of 30 to 42 years). After a long period with no medication (12 years), she was placed on denosumab. On the day she was due to take the fourth injection, she had sudden back pain, and magnetic resonance imaging (MRI) showed a grade II fracture at T9. She had simply forgot to take the scheduled dose of denosumab. Three months later, she presented with several episodes of severe back pain and loss of height and was diagnosed with multiple new severe vertebral fractures. This case illustrates an uncommon and severe bone disease following the inadvertent discontinuation of denosumab treatment.
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