Tumor-induced osteomalacia (TIO) is a rare but potentially curable disease. It is caused by excessive renal clearance of phosphate induced by a substance secreted from the tumor. Here, the authors report a Thai patient who presented with multiple pathologic fractures, low serum phosphorus, and low tubular maximum reabsorption of phosphorus/glomerular filtration rate (TmPO4/GFR). The clinical, biochemical and bone abnormalities improved 6 months after the surgery. Two years follow-up showed no recurrence of the disease. Physicians should be aware of this condition when encountering with adult onset osteomalacia.

Keyword : Tumor-induced osteomalacia, Oncogenic osteomalacia, Hypophosphatemic ricket, Hemangio-pericytoma, Fibroblast growth factor 23