Abstract: FR-PO270

Effect of Treatment of Metabolic Acidosis on Fibroblast Growth Factor-23 in Patients with CKD

Session Information

Category: Mineral Disease

  • 1202 Mineral Disease: Vitamin D, PTH, FGF-23

Authors

  • Shah, Pratik B., University of Colorado at Denver and Health Sciences Center, Denver, Colorado, United States
  • Andrews, Emily, University of Colorado Denver, Aurora, Colorado, United States
  • You, Zhiying, UC Denver, Aurora, Colorado, United States
  • Chonchol, Michel, University of Colorado, Aurora, Colorado, United States
  • Kendrick, Jessica B., University of Colorado Denver and Denver Health Medical Center, Denver, Colorado, United States
Background

The regulation of fibroblast growth factor-23 (FGF23) in patients with chronic kidney disease (CKD) is not understood. We conducted a study to test the hypothesis that treatment with oral sodium bicarbonate in patients with CKD and metabolic acidosis reduces intact FGF23 (iFGF23) levels.

Methods

We performed a prospective, randomized, open-label, 14 week crossover study of 20 subjects with stage 3B-4 CKD (eGFR 15-44 ml/min/1.73m2) and metabolic acidosis (serum bicarbonate level of <22 and ≥16 mEq/L). Subjects were randomly assigned to start with treatment or control. Each period was 6 weeks in duration with a 2 week washout period in between. Patients were treated with oral sodium bicarbonate tablets for goal bicarbonate > 22 mEq/L. Outcome measures were repeated at the beginning and end of each period. Mixed effects models were employed in comparison of pre-post change in iFGF23 and phosphorus between treatment and control groups.

Results

The mean (SD) age and eGFR was 58.5 ± 12.8 years and 24.6 ± 8.1 ml/min/1.73m2, respectively. iFGF23 increased significantly during the treatment period (p=0.008) and not during the control (p=0.68). When we compared iFGF23 between the treatment and the control periods, there was a trend towards significance (p=0.065). Serum phosphorus increased significantly during the treatment period but not in the control and the increase in phosphorus was significant between the groups (p=0.038). There was no significant change in serum parathyroid hormone or kidney function in either group.

Conclusion

Treatment of metabolic acidosis with sodium bicarbonate in CKD increases serum phosphorus and iFGF23. The mechanism of these observations is unexplained and further studies are needed to confirm these results.

 Control

Baseline
Control

6 weeks
P-valueTreatment

Baseline
Treatment

6 weeks
P-valueBetween group
P-value
Bicarbonate (mEq/L)19.7 ± 2.319.6 ± 3.20.9319.3 ± 2.922.0 ± 3.1<0.0010.005
iFGF23 (pg/mL)
Median [IQR]
239.8
[142.3-465.4]
209.5
[171.4-677.6]
0.68228.2
[149.6-362.6]
257.2
[176.2-832.3]
0.0080.065
Calcium (mg/dL)9.4 ± 0.59.2 ± 0.50.139.2 ± 0.59.3 ± 0.50.390.03
Phosphorus (mg/dL)4.2 ± 0.84.2 ± 1.10.854.1 ± 0.64.5 ± 1.10.020.04
PTH (pg/mL)
Median [IQR]
135 [72-266]149 [68-251]0.19138 [86-251]167 [101-385]0.130.89

Funding

  • NIDDK Support