Persistent high level of fibroblast growth factor 23 as a cause of post-renal transplant hypophosphatemia.

Post-transplant hypophosphatemia is a highly prevalent problem, and fibroblast growth factor 23, a newly discovered phosphatonin, has recently been reported to be involved in its pathogenesis. We report a 52-year-old Japanese woman who received a living-related kidney transplant and showed severe hypophosphatemia immediately after transplantation. We suspected that fibroblast growth factor 23 was the main cause of this hypophosphatemia and investigated its levels longitudinally after the transplantation. The patient showed persistently high levels of fibroblast growth factor 23, with suppressed 1,25-dihydroxyvitamin D and parathyroid hormone. She recovered from the hypophosphatemia when fibroblast growth factor returned to its reference level half a year after the transplantation. We conclude that a persistently high level of fibroblast growth factor 23 is an important cause of post-transplant hypophosphatemia, other than hyperparathyroidism, a previously noted cause.