Elevated FGF-23 in a patient with rhabdomyolysis-induced acute kidney injury.

Rhabdomyolysis-induced acute kidney injury (AKI) is characterized by hyperphosphataemia and hypocalcaemia. Despite appropriate secondary elevation of parathyroid hormone (PTH) in response to hypocalcaemia, rhabdomyolysis and AKI are associated with acute deficiency of 1,25-dihydroxycholecalciferol (1,25(OH)(2)D(3)), and yet, the mechanism responsible for such a deficiency remains unclear. Fibroblast growth factor 23 (FGF-23), a potent phosphaturic hormone that inhibits 25-hydroxyvitamin D(3)-1alpha-hydroxylase, could explain the deficiency of 1,25(OH)(2)D(3) in this setting. Here, we document, for the first time, elevated levels of FGF-23 in a patient with rhabdomyolysis-induced AKI.