Bone Mineral Density and Bone Quality Trends in a Child on Steroid Therapy Who Developed a Vertebral Fracture: A Case Report

Glucocorticoids (GCs) are commonly used to treat kidney problems in children and usually work well, but they can sometimes cause bone thinning, which may lead to fractures in the spine. Despite this, there is currently no established clinical approach for managing GC-induced osteoporosis (GIOP) in pediatric patients, highlighting the need for more data. Bone strength reflects both bone mineral density (BMD) and bone quality, with BMD assessed by X-ray and bone quality evaluated through serum or urine bone turnover markers (BTMs). In this case, a seven-year-old girl diagnosed with Henoch-Schönlein purpura nephritis was monitored over a two-year period during steroid treatment. Her BMD and serum BTMs, including alkaline phosphatase (ALP), tartrate-resistant acid phosphatase 5b (TRACP-5b), and undercarboxylated osteocalcin (ucOC), were tracked throughout the course. One month after initiating steroid therapy, her serum ALP (S-ALP) level decreased by 27.1% from baseline, while serum TRACP-5b (S-TRACP-5b) and serum ucOC increased by 34.4% and 52.3%, respectively, although BMD remained unchanged. Two months into treatment, she developed thoracic vertebral fractures (VFs) and was diagnosed with GIOP, prompting the initiation of oral alendronate sodium hydrate. Following the introduction of antiresorptive therapy and a reduction in GC dosage, both S-ALP and S-TRACP-5b levels returned to baseline by six months, accompanied by an 8.8% increase in BMD compared to the one-month level. No further fractures were observed after the cessation of antiresorptive treatment, which was guided by serial monitoring of BMD and BTMs. This case underscores the association of VFs with a decline in bone formation markers and elevations in bone resorption and matrix-related markers and demonstrates how BTMs reflecting bone quality can aid in determining the optimal duration of antiresorptive treatment in pediatric patients with GIOP.