FGF23 and hypophosphatemia: ,37 In clinical practice, acquired-onset FGF23-related hypophosphatemia has been treated as TIO after excluding a history of iron infusion therapy even when a causative PMT was not identified; however, there are other etiologies for acquired-onset FGF23-related hypophosphatemia, including neurofibromatosis 1, fibrous dysplasia, and alcoholic osteomalacia.2