Possible involvement of circulating fibroblast growth factor 23 in the development of secondary hyperparathyroidism associated with renal insufficiency

Am J Kidney Dis. 2004 Aug;44(2):250-6. doi: 10.1053/j.ajkd.2004.04.029.


Background: Fibroblast growth factor 23 (FGF-23) is a recently identified polypeptide that promotes renal phosphate excretion and decreases serum 1,25-dihydroxyvitamin D3 (1,25D) levels. Serum FGF-23 levels are extraordinarily elevated in patients with end-stage renal failure.

Methods: Blood and urine samples were obtained from 62 predialysis patients (age, 51.3 +/- 14.0 years; range, approximately 18 to 76 years; 32 men, 30 women). Serum FGF-23 levels were determined by means of a sandwich enzyme-linked immunosorbent assay system using 2 kinds of monoclonal antibodies that does not detect biologically inactive N-terminal and C-terminal fragments derived from an identified internal cleavage site to date.

Results: Serum FGF-23 levels increased with the decrease in creatinine clearance (Ccr). Both intact parathyroid hormone (PTH) and 1-84 PTH levels correlated closely with FGF-23 levels (r2 = 0.857; r2 = 0.860). A negative correlation between serum concentrations of FGF-23 and 1,25D (r2 = 0.255) was found. The maximum tubular reabsorptive rate of phosphate correlated negatively with serum FGF-23 concentrations (r2 = 0.460). However, the amount of daily urinary phosphate excretion was significantly less in patients with a Ccr less than 30 mL/min (<0.50 mL/s; P < 0.01), whereas their circulating FGF-23 levels were significantly greater (P < 0.001).

Conclusion: Circulating FGF-23 levels increase with the decrease in renal function. FGF-23 is a likely candidate to lead the reduction in serum 1,25D levels. FGF-23 becomes a potential uremic toxin to decrease 1,25D levels when it loses its hypophosphatemic action because of a decreased number of viable nephrons in patients with advanced renal failure. As such, FGF-23 may be an important determinant in the regulation of mineral metabolism with renal insufficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Calcitriol / blood
  • Calcium / blood
  • Creatinine / blood
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Fibroblast Growth Factor-23
  • Fibroblast Growth Factors / blood
  • Fibroblast Growth Factors / physiology*
  • Glomerulonephritis / complications
  • Humans
  • Hyperparathyroidism, Secondary / blood
  • Hyperparathyroidism, Secondary / etiology*
  • Kidney Failure, Chronic / complications*
  • Kidney Failure, Chronic / metabolism
  • Kidney Failure, Chronic / pathology
  • Kidney Tubules / metabolism
  • Male
  • Middle Aged
  • Nephrons / metabolism
  • Nephrons / pathology
  • Parathyroid Hormone / blood
  • Phosphates / urine


  • FGF23 protein, human
  • Parathyroid Hormone
  • Phosphates
  • Fibroblast Growth Factors
  • Fibroblast Growth Factor-23
  • Creatinine
  • Calcitriol
  • Calcium