Denosumab for Glucocorticoid-treated Children With Rheumatic Disorders

Inclusion Criteria: 1. Age 4 to 16 years of age. 2. Diagnosis of one of the following by a rheumatologist using standard criteria: juvenile dermatomyositis, juvenile idiopathic arthritis, systemic arthritis, seronegative or seropositive polyarthritis, psoriatic arthritis, systemic lupus or systemic vasculitis. 3. Within 1 month of initiating glucocorticoids ≥0.5 mg/kg prednisone equivalent daily, planned for ≥ 6 months. 4. BMD by DXA with Z-score \< 0.0 on screening at lumbar spine or total body less head (TBLH). Exclusion Criteria: 1. Previous treatment with a bisphosphonate, or other osteoporosis medication. 2. Metabolic bone disorders besides glucocorticoid-induced osteoporosis; other disorders treated with systemic glucocorticoids (inflammatory bowel disease, severe pulmonary disease, nephrotic syndrome, etc.). 3. Intent to treat with a tumor necrosis factor inhibitor or Interleukin 6 receptor antagonist during the first 6 months. 4. Glomerular filtration rate \< 30ml/min \[pediatric estimated glomerular filtration rate = 0.413\*(height/serum creatinine)\] 75 5. Planned orthopedic or other major surgery during the course of the study (at the time of enrollment) 6. Significant dental caries, or plans to undergo invasive oral procedures during the subsequent 12 months. 7. Known allergy to latex (drug packaging includes a natural rubber stopper), fructose intolerance or other denosumab contraindication. 8. 25-hydroxyvitamin D (25OHD) level \< 32 ng/dl. Subjects with 25OHD \<32 ng/ml may be given cholecalciferol and rescreened. 9. Hypocalcemia at screening (total serum calcium \< 8.5 mg/dl after correction for albumin level). 10. Chronic ventilator dependence, or other conditions increasing risk of participation. 11. Pregnancy, or refusal to use acceptable contraception or abstain during the protocol (post-pubertal female).