1 Division of Endocrinology and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
2 Department of Clinical, Internal, Anesthesiology and Cardiovascular Sciences, Sapienza University, Rome, Italy.
3 Department of Endocrinology, Key Laboratory of Endocrinology, State Key Laboratory of Complex Severe and Rare Diseases, NHC, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China.
4 Open Patient data Explorative Network (OPEN), Department of Clinical Research, University of Southern Denmark and Odense University Hospital, Odense, Denmark.
5 Department of Medicine, Holbaek Hospital, Holbaek, Denmark.
6 Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
7 Department of Medicine, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium.
8 Department of Surgery and Translational Medicine, University of Florence, University Hospital of Florence, Florence, Italy.
9 Department of Endocrinology and Diabetes, Royal North Shore Hospital, Sydney, Australia.
10 Cancer Genetics Unit, Kolling Institute, Sydney, Australia.
11 Sydney Medical School, University of Sydney, Sydney, Australia.
12 Skeletal Diseases and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA.
13 Centro Traslacional de Endocrinología UC (CETREN-UC), Endocrinology Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
14 Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Département des Maladies Rénales et Métaboliques, Hôpital Européen Georges-Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France.
15 Department of Metabolism, Endocrinology, and Molecular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan.
16 Division of Endocrinology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
17 Division of Endocrinology and Metabolism, Calcium Disorders Clinic, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
18 Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
19 Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan.
Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome caused by mesenchymal tumors that secrete fibroblast growth factor 23 (FGF23). Patients present with progressive bone pain, muscle weakness, and fragility fractures. TIO is characterized by hypophosphatemia, excess renal phosphate excretion, and low/inappropriately normal 1,25-dihydroxyvitamin D (1,25(OH)2 D) levels. Rarity and enigmatic clinical presentation of TIO contribute to limited awareness among the medical community. Accordingly, appropriate diagnostic tests may not be requested, leading to delayed diagnosis and poorer patient outcomes. We have developed a global guidance document to improve the knowledge of TIO in the medical community, enabling the recognition of patients with TIO and appropriate referral. We provide recommendations aiding diagnosis, referral, and treatment, helping promote a global standard of patient management. We reviewed the literature and conducted a three-round Delphi survey of TIO experts. Statements were drafted based on published evidence and expert opinions (≥70% consensus required for final recommendations). Serum phosphate should be measured in patients presenting with chronic muscle pain or weakness, fragility fractures, or bone pain. Physical examination should establish features of myopathy and identify masses that could be causative tumors. Priority laboratory evaluations should include urine/serum phosphate and creatinine to assess renal tubular reabsorption of phosphate and TmP/GFR, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, 1,25(OH)2 D, and FGF23. Patients with the clinical/biochemical suspicion of TIO should be referred to a specialist for diagnosis confirmation, and functional imaging should be used to localize causative tumor(s). Recommended treatment is tumor resection or, with unresectable/unidentifiable tumors, phosphate salts plus active vitamin D, or burosumab.