Fibroblast growth factor-23 mitigates hyperphosphatemia but accentuates calcitriol deficiency in chronic kidney disease

Orlando Gutierrez, Tamara Isakova, Eugene Rhee, Anand Shah, Julie Holmes, Gina Collerone, Harald Jüppner, Myles Wolf*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

663 Scopus citations

Abstract

Hyperphosphatemia, calcitriol deficiency, and secondary hyperparathyroidism (SHPT) are common complications of chronic kidney disease (CKD). Fibroblast growth factor-23 (FGF-23) is a novel phosphaturic hormone that also inhibits renal 1α-hydroxylase activity and thus may be involved in the pathogenesis of SHPT. Several hypotheses were tested: that FGF-23 increases as renal function declines; is linearly associated with serum phosphate levels; is associated with increased phosphaturia independent of parathyroid hormone (PTH); and is associated with decreased calcitriol levels independent of renal function, hyperphosphatemia, and vitamin D stores. FGF-23, PTH, 25(OH)D 3, calcitriol, calcium, phosphate, and urinary fractional excretion of phosphate (FePO4) were measured in 80 CKD patients. Multiple linear regression was used to test the hypotheses. FGF-23 and PTH were inversely associated with estimated GFR (eGFR), whereas calcitriol levels were linearly associated with eGFR. Hyperphosphatemia and hypocalcemia were present in only 12 and 6% of patients, respectively, all of whose eGFR was <30. Increased FePO4 was associated with decreased eGFR, and both increased FGF-23 and PTH were independently associated with increased FePO4. Increased FGF-23 and decreased 25(OH)D3 were independent predictors of decreased calcitriol, but the effects on calcitriol levels of renal function itself and hyperphosphatemia were completely extinguished by adjusting for FGF-23. It is concluded that FGF-23 levels increase early in CKD before the development of serum mineral abnormalities and are independently associated with serum phosphate, FePO4, and calcitriol deficiency. Increased FGF-23 may contribute to maintaining normal serum phosphate levels in the face of advancing CKD but may worsen calcitriol deficiency and thus may be a central factor in the early pathogenesis of SHPT.

Original languageEnglish (US)
Pages (from-to)2205-2215
Number of pages11
JournalJournal of the American Society of Nephrology
Volume16
Issue number7
DOIs
StatePublished - 2005

ASJC Scopus subject areas

  • Nephrology

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