Abstract
Denosumab, a fully humanized monoclonal antibody, has been used for the treatment
of osteoporosis, in complications resulting from bone metastatic disease and in giant
cell tumor in both adults and skeletally mature adolescents. Denosumab is an inhibitor
of the receptor activator of nuclear factor kappa-B ligand and belongs to a new class
of antiresorptive medications. We report a unique case of myopathy in a 13-year-old
boy prescribed denosumab for enchondromatosis. The boy presented with hypovitaminosis
D, elevated parathyroid hormone, suppressed alkaline phosphatase, hypocalcemia, and
hypophosphatemia after a single dose of denosumab. Our case points to altered calcium–vitamin
D homeostasis induced by denosumab. Myopathy associated with denosumab has not been
described previously in children. Early recognition of myopathy and adequate supplementation
with calcium–vitamin D may ensure a more favorable clinical outcome.
Keywords
denosumab - myopathy - hypovitaminosis D - calcium - weakness
