Fibroblast Growth Factor 23, Mineral Metabolism, and Adiposity in Normal Kidney Function.
Obesity is associated with poor bone mineralization and quality. Fibroblast growth factor 23 (FGF23) plays an important role in skeletal physiology.



To test hypothesis that greater adiposity results in higher FGF23 levels among individuals with normal estimated glomerular filtration rate (eGFR).



Cross-sectional analyses among participants with eGFR ≥60 mL/min/1.73m2. We assessed the association between crude [body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR); n = 5610] and refined (abdominal adipose tissue area by computed tomography; n = 1313) measures of adiposity and FGF23 using multivariable linear regression.



Serum FGF23.



FGF23 was higher across BMI categories (BMI <25: 37.7; BMI 25 to 29.99: 38.7; BMI 30 to 39.99: 39.8; BMI ≥40: 40.9 pg/mL, unadjusted P trend < 0.0001). The association between BMI and FGF23 was independent of known confounders of FGF23 (adjusted β = +7.2% higher FGF23 per 10 kg/m2; P < 0.0001). Similar results were observed using WC and WHR. Abdominal adipose tissue area was also independently associated with higher FGF23 (P < 0.01). Notably, the positive associations between FGF23 and adiposity were observed despite the fact that eGFR did not decline and serum phosphate levels did not increase with adiposity.



In a large cohort with normal kidney function, adiposity was associated with higher FGF23 levels independent of known confounders, including eGFR and phosphate. Further studies are needed to evaluate the causes of higher FGF23 in settings of greater adiposity and the potential impact on skeletal health.
Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
Sarah
S
Zaheer
Division of Nephrology, Department of Medicine, and.
Ian H
IH
de Boer
Division of Preventive Medicine, University of California, San Diego, San Diego, California 92093.
Matthew
M
Allison
Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
Jenifer M
JM
Brown
Cardiovascular Health Research Unit, Departments of Medicine, Epidemiology and Health Services, University of Washington, Seattle, Washington 98195.|Group Health Research Institute, Group Health Cooperative, Seattle, Washington 98101.
Bruce M
BM
Psaty
Division of Nephrology, Department of Medicine, and.|Kidney Research Institute, University of Washington, Seattle, Washington 98104.
Cassianne
C
Robinson-Cohen
Division of Cardiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
Erin D
ED
Michos
Division of Nephrology-Hypertension, University of California, San Diego, San Diego, California 92161.
Joachim H
JH
Ix
Division of Nephrology, Department of Medicine, and.|Kidney Research Institute, University of Washington, Seattle, Washington 98104.
Bryan
B
Kestenbaum
The New York Academy of Medicine, New York, New York 10029.
David
D
Siscovick
Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
Anand
A
Vaidya
D050154:Adiposity / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000378:metabolism*; D051436:Renal Insufficiency, Chronic / Q000378:metabolism / Q000503:physiopathology; D012307:Risk Factors
C000717427:FGF23 protein, human; D008903:Minerals; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23