Denosumab for Post-Transplantation Hypercalcemia in Osteopetrosis

Abstract

To the Editor: Hematopoietic stem-cell transplantation (HSCT) is the only cure for osteopetrosis, a heterogeneous group of heritable disorders characterized by defective osteoclast-mediated bone resorption.1 Restitution of osteoclast function by HSCT can be associated with severe hypercalcemia.2 We describe two children (12 years and 3 years of age) with osteopetrosis due to a homozygous loss-of-function mutation in the gene TNFRSF11A that encodes receptor activator of nuclear factor κB (RANK), a key regulator of osteoclastogenesis and osteoclast function.3 Prior to HSCT, both patients had vitamin D deficiency, low serum calcium levels (<8.6 mg per deciliter [<2.2 mmol per liter]), and elevated . . .