The relationship between circulating fibroblast growth factor 23 and bone metabolism factors in Korean hemodialysis patients.
BACKGROUND
Fibroblast growth factor 23 (FGF-23) is a circulating factor that acts as a phosphaturic factor in the kidneys. It is also involved in several disorders of phosphate regulation and bone metabolism. We hypothesized that increased FGF-23 levels in patients with endstage renal disease (ESRD) on maintenance hemodialysis would be associated with increased bone demineralization, and we analyzed the relationship between FGF-23 levels and bone mineral density (BMD).


METHODS
The serum level of FGF-23 was measured in this cross-sectional study, whose subjects consisted of 54 patients with ESRD on maintenance hemodialysis. Clinical parameters associated with hemodialysis and bone metabolism were measured. The relationship between serum FGF-23 and BMD and the factors affecting the serum level of FGF-23 were analyzed.


RESULTS
Serum FGF-23 levels were significantly higher in ESRD patients on maintenance hemodialysis than in normal persons (2961.4 vs. 30 pg/ml). Multiple regression analysis showed that increasing FGF-23 levels were associated with serum phosphate (r = 0.684, P < 0.001), but not with BMD or other bone metabolism factors. Factors affecting log(10)FGF-23 included the serum calcium phosphate product (beta = 0.603) and K (t)/V (integrated fractional clearance expressed per dialysis, beta = -0.244). These results were also seen in an analysis of the correlations based on T score or gender.


CONCLUSIONS
FGF-23 levels were positively associated with serum phosphate levels but were not correlated with BMD. The only factors affecting log(10)FGF-23 were the serum calcium phosphate product and K (t)/V. These findings suggest that FGF-23 may have no direct effect on bone mineralization, and further studies are warranted to examine the effects of FGF-23 on vitamin D metabolism.
Park
So-Youn
SY
Department of Nephrology, Kyung Hee University School of Medicine, Dongdaemun-Gu, Seoul, 130-701, Korea.
Jeong
Kyung-Hwan
KH
Moon
Ju-Young
JY
Lee
Sang-Ho
SH
Ihm
Chun-Gyoo
CG
Rhee
Sang Youl
SY
Woo
Jeong-Taek
JT
Oh
In-Hwan
IH
Lee
Tae-Won
TW
D000368:Aged; D018488:Bone Demineralization, Pathologic / Q000503:physiopathology*; D015519:Bone Density / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000097:blood; D006435:Renal Dialysis
C000717427:FGF23 protein, human; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23