title: Pathologic femur fracture due to a brown tumor in a patient with secondary hyperparathyroidism and vitamin D-resistant rickets.
abstract: Vitamin D-resistant rickets is the common clinical outcome of multiple genetic mutations that alter the regulation of phosphorus and vitamin D metabolism, mainly through their effects on fibroblast growth factor 23 (FGF-23). These diseases typically present in childhood with the classic physical examination finding of nutritional rickets, such as genu varum/valgum and rachitic rosary. Treatment, which is aimed at improving severe bone disease with vitamin D and phosphorus supplementation, can cause secondary hyperparathyroidism and/or kidney failure from nephrocalcinosis over the life of the patient. Although FGF-23 has been shown to downregulate parathyroid hormone in vitro, its effect on parathyroid secretion in disease states such as chronic kidney disease and X-linked hypophosphatemic rickets is unclear because elevations in FGF-23 and parathyroid hormone levels characterize both of these disease states. We describe a case of vitamin D-resistant rickets that presented with a femur fracture through a brown tumor. Radiographs show the combination of severe bony abnormalities associated with both long-standing hyperparathyroidism and vitamin D-resistant rickets.
authors.affiliation: Nephrology Division, University of Alabama at Birmingham, Birmingham, AL, USA. ericlwallace@uab.edu
authors.forename: Eric
authors.initials: E
authors.lastname: Wallace
authors.forename: Matthew
authors.initials: M
authors.lastname: Day
authors.forename: Oluwole
authors.initials: O
authors.lastname: Fadare
authors.forename: Heidi
authors.initials: H
authors.lastname: Schaefer
mesh_terms: D000328:Adult; D001859:Bone Neoplasms / Q000150:complications*; D004351:Drug Resistance; D005260:Female; D005264:Femoral Fractures / Q000209:etiology*; D000089703:Fibroblast Growth Factor-23; D005598:Fractures, Spontaneous / Q000209:etiology*; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000150:complications*; D012279:Rickets / Q000150:complications* / Q000188:drug therapy; D014807:Vitamin D / Q000627:therapeutic use
chemical_list: C000717427:FGF23 protein, human; D014807:Vitamin D; D000089703:Fibroblast Growth Factor-23