FGF-23 and sFRP-4 in chronic kidney disease and post-renal transplantation

Nephron Physiol. 2006;104(1):p23-32. doi: 10.1159/000093277. Epub 2006 May 10.


Background: The phosphatonins fibroblast growth factor-23 (FGF-23) and FRP-4 are inhibitors of tubular phosphate reabsorption that may play a role in the hyperphosphatemia associated with chronic kidney disease (CKD) or in the hypophosphatemia associated with renal transplants.

Methods: Plasma FGF-23, FRP-4, phosphorus and parathyroid hormone were measured in patients at all stages of CKD. Phosphate regulation of FGF-23 and secreted frizzled related protein-4 (sFRP-4) was examined in end-stage renal disease patients in the presence and absence of therapeutic phosphate binder usage. In renal transplant patients, plasma FGF-23, sFRP-4 and phosphorus concentrations were determined before and 4-5 days after transplantation.

Results: Plasma FGF-23 correlated with creatinine clearance (r2 = -0.584, p < 0.0001) and plasma phosphorus (r2 = 0.347, p < 0.001) in CKD patients and with plasma phosphorus (r2 = 0.448, p < 0.001) in end-stage renal disease patients. Phosphate binder withdrawal increased FGF-23 levels. In kidney transplant patients, dramatic decreases in FGF-23 (-88.8 +/- 5.4%) and phosphorus (-64 +/- 10.2%) were observed by 4-5 days post-transplantation. In patients with post-transplant hypophosphatemia, FGF-23 levels correlated inversely with plasma phosphorus (r2 = 0.661, p < 0.05). sFRP-4 levels did not change with creatinine clearance or hyperphosphatemia in CKD or end-stage renal disease patients, and no relation was noted between post-transplant sFRP-4 levels and hypophosphatemia.

Conclusions: In CKD, FGF-23 levels rose with decreasing creatinine clearance rates and increasing plasma phosphorus levels, and rapidly decreased post-transplantation suggesting FGF-23 is cleared by the kidney. Residual FGF-23 may contribute to the hypophosphatemia in post-transplant patients.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Female
  • Fibroblast Growth Factors / blood*
  • Humans
  • Hypophosphatemia / blood
  • Hypophosphatemia / metabolism*
  • Kidney Failure, Chronic / blood
  • Kidney Failure, Chronic / metabolism*
  • Kidney Transplantation*
  • Kidney Tubules / metabolism
  • Male
  • Parathyroid Hormone / blood
  • Phosphates / blood
  • Phosphates / metabolism
  • Postoperative Complications / blood
  • Proto-Oncogene Proteins / blood*


  • Parathyroid Hormone
  • Phosphates
  • Proto-Oncogene Proteins
  • SFRP4 protein, human
  • Fibroblast Growth Factors
  • fibroblast growth factor 23