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Abstract: TH-PO192

Effect of Ferric Citrate Hydrate on FGF23 and Serum α-Klotho in Hemodialysis Patients with Hyperphosphatemia and Controlled Serum Phosphate Levels: ASTRIO Study, Supplementary Analysis

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical


  • Yokoyama, Keitaro, Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
  • Fukagawa, Masafumi, Tokai University School of Medicine, Isehara, KANAGAWA, Japan
  • Nakayama, Masaaki, St Luke''s International Hospital, Tokyo, Japan
  • Kyoko, Ito, Torii Pharmaceutical Co., Ltd, Tokyo, Japan
  • Hanaki, Koji, Japan Tobacco Inc., Tokyo, Japan
  • Hirakata, Hideki, Fukuoka Renal Clinic, Fukuoka City, Japan

Elevated serum Fibroblast Growth Factor (FGF) 23 level is an independent risk factor for the progression to ESRD, and high FGF23 levels are reportedly associated with cardiovascular events. There is growing interest in α-klotho, a co-receptor for FGF23, as a biomarker of kidney function, because low α-klotho levels have been associated with adverse kidney disease outcome. However, the effect of phosphate binders (PBs) on α-klotho has not been extensively evaluated.


ASTRIO was a prospective, randomized, multicenter, 24-week study. 93 HD patients who had been taking non-iron based PBs were randomized to Ferric Citrate Hydrate (FC) group (n=45) or Control group (n=48). In Control, patients maintained treatment with their existing PBs. Serum P and Hb were controlled within 3.5 to 6.0 mg/dL and 10.0 to 12.0 g/dL, respectively. The primary endpoint was change in ESA dose; we also evaluated serum FGF23 and α-klotho.


Serum P was maintained in both groups. C-terminal FGF23 (cFGF23) significantly decreased in FC compared to Control (p=0.04). There were no statistical differences in the changes in intact FGF23 (iFGF23) and α-klotho between groups. Serum ferritin and TSAT were significantly increased in FC compared to Control.


In this study, while there was no difference in the change of serum P between the groups, cFGF23 significantly decreased in FC compared to Control, but did not change iFGF23 and α-klotho.

ParameterFC (N=40)
Mean (SD) Change
(from baseline to EOT**)
Control (N=42)
Mean (SD) Change
(from baseline to EOT**)
Adjusted Mean
Difference (FC minus Control)
P (mg/mL)0.24 (1.59)-0.17 (1.53)0.550.06
Ferritin (ng/mL)79.0 (81.5)2.9 (79.3)79.5<0.01
TSAT (%)8.6 (12.1)0.5 (11.8)9.0<0.01
cFGF23 (pg/mL)*-0.2 (0.8)0.2 (0.8)0.70.04
iFGF23 (pg/mL)*-0.1 (0.8)0.1 (0.9)0.80.33
α-klotho (pg/mL)2.0 (91.5)-8.9 (145.3)-11.10.58

*Logarithmic transformation, **End of treatment