SUN-804 - Marked Lumbar Spine BMD Gains with Romosozumab in A Postmenopausal Woman with Polymyositis and Severe Osteoporosis: A Case Report

Background: Romosozumab is a sclerostin inhibitor with dual effects on bone remodeling (increased bone formation and reduced bone resorption) and is recommended for postmenopausal women at very high fracture risk for a 12-month course followed by antiresorptive therapy to maintain gains. (2–4) In pivotal trials, typical 12-month lumbar spine BMD increases are ~13–14%. (3,4)

Case: A 64-year-old postmenopausal woman with polymyositis, celiac disease (adherent to a gluten-free diet), and severe osteoporosis was referred for management after intolerance to oral bisphosphonates and prior intravenous zoledronic acid exposure. Baseline DXA (2023) showed lumbar spine T-score −3.0 (BMD 0.716 g/cm²). She completed 12 monthly doses of romosozumab with a planned transition to an antiresorptive agent afterward. (2)

Results: Post-treatment DXA demonstrated lumbar spine BMD increased from 0.716 to 0.908 g/cm² (absolute +0.192 g/cm²; +26.82%) with T-score improvement from −3.0 to −1.3. Femoral neck and total hip BMD changes were modest (+1.82% and +4.98%, respectively).

Conclusion: This case demonstrates an unusually large lumbar spine BMD gain after romosozumab. When spine BMD gains are unexpectedly large, clinicians should consider clinical contributors (e.g., low baseline BMD, adherence, absence of glucocorticoids) and assess for potential DXA artifacts such as interval vertebral fractures or degenerative change. (10) Whether inflammatory myopathies influence anabolic treatment responsiveness remains uncertain and warrants further study. (5–7)

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