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Abstract: TH-PO347

The Effect of Frequent Hemodialysis on Phosphate and Fibroblast Growth Factor 23: Results from the Frequent Hemodialysis Network Trials

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Chan, Christopher T., Toronto General Hospital, Toronto, Ontario, Canada
  • Kaysen, George A., UC Davis, Sacramento, California, United States
  • Beck, Gerald J., Cleveland Clinic Foundation, Cleveland, Ohio, United States
  • Rocco, Michael V., Wake Forest School of Medicine, Winston-Salem, North Carolina, United States
  • Kliger, Alan S., Yale New Haven Health System, New Haven, Connecticut, United States

Group or Team Name

  • FHN Trials Group

Hyperphosphatemia is associated with elevations in fibroblast growth factor 23 (FGF23) and blood pressure in patients with end-stage kidney disease (ESKD). We aimed to ascertain whether reduction in phosphate by frequent hemodialysis is associated with specific changes in biomarker profile amongst patients enrolled in the Frequent Hemodialysis Network (FHN) trials.


This was a post hoc observational cohort study. We hypothesized that reduction in phosphate is associated with changes in FGF23. We further hypothesized that changes in FGF23 may correlate with variations in blood pressure and markers of collagen turnover.


Among 332 randomized patients, 243 had biomarker data available. Of these, 124 were assigned 3 times a week hemodialysis (94 [Daily Trial] and 30 [Nocturnal Trial]) and 119 patients were assigned to 6 times a week hemodialysis (87 [Daily Trial] and 32 [ Nocturnal Trial]). Frequent hemodialysis lowered phosphate, blood pressures, logFGF23 and tissue inhibitors of metalloproteinase (TIMP) - 2 levels. The fall in phosphate correlated to the changes in FGF23 (r = 0.48, p <0.001 [Daily Trial] and r = 0.55, p < 0.001 [Nocturnal Trial]) and trended with changes in systolic blood pressure (r = 0.18, p = 0.057 [Daily Trial] and (r = 0.31, p = 0.04) [Nocturnal Trial].


Reduction of serum phosphate by frequent hemodialysis may modulate FGF23 levels and systolic blood pressure. Frequent hemodialysis may affect pathological mediators of chronic kidney disease – mineral bone-metabolism disorder.

Effect (95% CI) of hemodialysis frequency on phosphate, blood pressure and selected biomarkers
VariablesDaily Trial (3x/week))Daily Trial (6x/week)p-value (3x vs. 6x)Nocturnal (3x/week)Nocturnal (6x/week)p-value (3x vs. 6x)
Phosphate (mg/dL)0.02 (-0.3;0.4)-0.5 (-0.9; -0.2)*0.010.3 (-0.4; 1.0)-1.1 (-1.8; -0.4)*0.004
LogFGF23 (%**)-14.0 (-38.8; 21.0)-43.9 (-59.5; -22.5)*0.051-9.0 (-50.0; 65.6)-46.2 (-71.2;0.5)#0.22
Systolic blood pressure (mmHg)-2.0 (-6.7; 2.6)-8.1 (-12.5;-3.7)*0.038-3.7 (-10.3; 3.0)-14.9 (-21.8; -7.9)*0.019
Diastolic blood pressure (mmHg)-0.7 (-3.4; 2.0)-4.5 (-7.0; -1.9)*0.027-0.5 (-4.6; 3.6)-4.7 (-8.9; -0.4)*0.15
TIMP-2 (pg/ml)-3888.8 (-11080.2;3302.6)-14632.5 (-21728.2;-7536.9)*p<0.0001-11966.0 (-22090.7;-1841.4)*-14936.5(-25208.4;-4664.5)*0.56

* denotes p < 0.05 (within group); # p =0.052 (within group); **expressed as percent difference based on log transformed analysis


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