Fibroblast growth factor-23 and early decrements in kidney function: the Heart and Soul Study.
BACKGROUND
Fibroblast growth factor-23 (FGF-23) is associated with mortality in dialysis patients, and concentrations are elevated in moderate chronic kidney disease (CKD). The threshold of CKD or albuminuria at which FGF-23 begins to change is unknown.


METHODS
In 792 outpatients with stable cardiovascular disease (CVD) and normal kidney function to moderate CKD, we evaluate the associations of estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) with plasma FGF-23 concentrations.


RESULTS
Compared to participants with eGFR >or=90 ml/min/1.73 m(2), mean FGF-23 concentrations were 7.8 RU/ml higher (4.3-11.5, P = 0.01) in those with eGFR 60-89 ml/min/1.73 m(2) in models adjusted for age, sex, race, ACR, blood pressure, diabetes and body mass index. More advanced decrements in eGFR were associated with much higher FGF-23 concentrations. In spline analysis, the slope of change in FGF-23 concentration was evident at eGFR <90 ml/min/1.73 m(2). Compared to participants with ACR <30 mg/g, mean FGF-23 concentrations were 18.4 RU/ml higher (9.3-29.2, P < 0.001) in those with ACR 30-299 mg/g in models adjusted for identical covariates plus eGFR and much higher in individuals with ACR >or=300 mg/g. Spline analysis demonstrated a linear relationship of ACR with FGF-23, independent of eGFR, even among persons with ACR <30 mg/g.


CONCLUSIONS
Modest decrements in eGFR or elevations in albuminuria are each independently associated with higher FGF-23 concentrations in outpatients with stable CVD.
Ix
Joachim H
JH
Division of Nephrology, Department of Medicine, University of California San Diego, San Diego, CA, USA. joeix@ucsd.edu
Shlipak
Michael G
MG
Wassel
Christina L
CL
Whooley
Mary A
MA
D000368:Aged; D000419:Albuminuria / Q000097:blood / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000097:blood / Q000503:physiopathology; D002908:Chronic Disease; D003404:Creatinine / Q000652:urine; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007674:Kidney Diseases / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D003404:Creatinine