Tumor-induced osteomalacia: Easing the diagnosis with fibroblast growth factor 23

Tumor-induced osteomalacia (TIO), is a rare paraneoplastic syndrome resulting in bone pain, muscle weakness, and recurrent fractures. Hypophosphatemia, hyperphosphaturia, low 1, 25 dihydroxyVitamin D, and normal serum calcium are noted. It is mostly caused by fibroblast growth factor 23 (FGF23) secreting tumors. Apart from testing for FGF23, additional imaging modalities are required to identify the causative lesion. Prompt remission follows successful lesion excision. This case report highlights the importance of FGF 23 in the diagnosis of TIO.