A recent study shows a strong association between the development of hyperphosphatemia in dogs with chronic kidney disease and increased serum levels of fibroblastic growth factor-23 (FGF-23)

Miyakawa H, Hsu H-H, Ogawa M, Akabane R, Miyagawa Y, Takemura N. Association between serum fibroblast growth factor-23 concentration and development of hyperphosphatemia in normophosphatemic dogs with chronic kidney disease. J Vet Intern Med. 2021;35(5):2296-2305. Full Text.


Chronic kidney disease (CKD) is a common, irreversible, and progressive disease in dogs. In patients with CKD, mineral metabolism disorders such as hyperphosphatemia, renal hyperparathyroidism, and decreased calcitriol synthesis also occur because of impaired renal function. These disorders are termed CKD—mineral and bone disorder (MBD). Hyperphosphatemia (abnormally high serum phosphate levels) is known to be a prognostic factor for shorter survival time in dogs with CKD.

The role of FGF-23 in CKD

Fibroblast growth factor-23 is released from osteocytes in response to increased serum phosphorus and calcitriol concentrations and promotes phosphate excretion into the urine by downregulation of the sodium-phosphate co-transporter in renal proximal tubular cells and inhibition of calcitriol synthesis. Fibroblast growth factor-23 acts by binding to the FGF receptor-α-klotho complex.13 In humans, cats, and dogs with CKD, circulating FGF-23 concentrations have been shown to increase in the advanced CKD stages. Increased FGF-23 concentration in CKD patients is associated with various mechanisms, such as a decreased clearance of FGF-23 because of decreasing glomerular filtration rate (GFR), compensation for the accumulation of phosphate in the body, and compensation for decreased klotho protein concentrations. Blood FGF-23 concentrations in dogs with CKD have been shown to become increased earlier than serum phosphorous concentrations therefore, FGF-23 has been noted as an early marker of CKD-MBD.

Researchers hypothesized that FGF-23 predicts development of hyperphosphatemia in normophosphatemic dogs with CKD. If correct, FGF-23 may be a useful marker of when to initiate a phosphate-restricted diet to prevent the development of hyperphosphatemia.

About the MedFrontier Intact FGF23 Assay

  • low sample volume required – only 20ul
  • ONLY assay that measures the full-length active form (intact form) of FGF23
  • superior dynamic range of 10-3000 pg/uL
  • CLEIA technology

The MedFrontier Intact FGF23 Assay was developed and manufactured by Minaris Medical.

IF you have any questions about this product or any of our other products, contact us here.