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Oral Iron Replacement Normalizes Fibroblast Growth Factor 23 in Iron-Deficient Patients With Autosomal Dominant Hypophosphatemic Rickets.
J Bone Miner Res. 2020 02; 35(2):231-238.JB

Abstract

Autosomal dominant hypophosphatemic rickets (ADHR) is caused by mutations impairing cleavage of fibroblast growth factor 23 (FGF23). FGF23 gene expression increases during iron deficiency. In humans and mice with the ADHR mutation, iron deficiency results in increased intact FGF23 concentrations and hypophosphatemia. We conducted a prospective open label pilot clinical trial of oral iron replacement over 12 months in ADHR patients to test the hypothesis that oral iron administration would normalize FGF23 concentrations. Eligibility criteria included: FGF23 mutation; and either serum iron <50 μg/dL; or serum iron 50 to 100 μg/dL combined with hypophosphatemia and intact FGF23 >30 pg/mL at screening. Key exclusion criteria were kidney disease and pregnancy. Oral iron supplementation started at 65 mg daily and was titrated based on fasting serum iron concentration. The primary outcome was decrease in fasting intact FGF23 by ≥20% from baseline. Six adults (three male, three female) having the FGF23-R176Q mutation were enrolled; five completed the 12-month protocol. At baseline three of five subjects had severely symptomatic hypophosphatemia (phosphorus <2.5 mg/dL) and received calcitriol with or without phosphate concurrent with oral iron during the trial. The primary outcome was met by 4 of 5 (80%) subjects all by month 4, and 5 of 5 had normal intact FGF23 at month 12. Median (minimum, maximum) intact FGF23 concentration decreased from 172 (20, 192) pg/mL at baseline to 47 (17, 78) pg/mL at month 4 and 42 (19, 63) pg/mL at month 12. Median ferritin increased from 18.6 (7.7, 82.5) ng/mL at baseline to 78.0 (49.6, 261.0) ng/mL at month 12. During iron treatment, all three subjects with baseline hypophosphatemia normalized serum phosphorus, had markedly improved symptoms, and were able to discontinue calcitriol and phosphate. Oral iron repletion normalized FGF23 and phosphorus in symptomatic, iron-deficient ADHR subjects. Thus, the standard approach to ADHR should include recognition, treatment, and prevention of iron deficiency. © 2019 American Society for Bone and Mineral Research.

Authors+Show Affiliations

Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA.Department of Biostatistics, Indiana University School of Public Health, Indianapolis, IN, USA.Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.

Pub Type(s)

Clinical Trial
Journal Article

Language

eng

PubMed ID

31652009

Citation

Imel, Erik A., et al. "Oral Iron Replacement Normalizes Fibroblast Growth Factor 23 in Iron-Deficient Patients With Autosomal Dominant Hypophosphatemic Rickets." Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, vol. 35, no. 2, 2020, pp. 231-238.
Imel EA, Liu Z, Coffman M, et al. Oral Iron Replacement Normalizes Fibroblast Growth Factor 23 in Iron-Deficient Patients With Autosomal Dominant Hypophosphatemic Rickets. J Bone Miner Res. 2020;35(2):231-238.
Imel, E. A., Liu, Z., Coffman, M., Acton, D., Mehta, R., & Econs, M. J. (2020). Oral Iron Replacement Normalizes Fibroblast Growth Factor 23 in Iron-Deficient Patients With Autosomal Dominant Hypophosphatemic Rickets. Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, 35(2), 231-238. https://doi.org/10.1002/jbmr.3878
Imel EA, et al. Oral Iron Replacement Normalizes Fibroblast Growth Factor 23 in Iron-Deficient Patients With Autosomal Dominant Hypophosphatemic Rickets. J Bone Miner Res. 2020;35(2):231-238. PubMed PMID: 31652009.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oral Iron Replacement Normalizes Fibroblast Growth Factor 23 in Iron-Deficient Patients With Autosomal Dominant Hypophosphatemic Rickets. AU - Imel,Erik A, AU - Liu,Ziyue, AU - Coffman,Melissa, AU - Acton,Dena, AU - Mehta,Rakesh, AU - Econs,Michael J, Y1 - 2019/10/25/ PY - 2019/06/05/received PY - 2019/08/20/revised PY - 2019/08/28/accepted PY - 2019/10/28/pubmed PY - 2021/7/3/medline PY - 2019/10/26/entrez SP - 231 EP - 238 JF - Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research JO - J Bone Miner Res VL - 35 IS - 2 N2 - Autosomal dominant hypophosphatemic rickets (ADHR) is caused by mutations impairing cleavage of fibroblast growth factor 23 (FGF23). FGF23 gene expression increases during iron deficiency. In humans and mice with the ADHR mutation, iron deficiency results in increased intact FGF23 concentrations and hypophosphatemia. We conducted a prospective open label pilot clinical trial of oral iron replacement over 12 months in ADHR patients to test the hypothesis that oral iron administration would normalize FGF23 concentrations. Eligibility criteria included: FGF23 mutation; and either serum iron <50 μg/dL; or serum iron 50 to 100 μg/dL combined with hypophosphatemia and intact FGF23 >30 pg/mL at screening. Key exclusion criteria were kidney disease and pregnancy. Oral iron supplementation started at 65 mg daily and was titrated based on fasting serum iron concentration. The primary outcome was decrease in fasting intact FGF23 by ≥20% from baseline. Six adults (three male, three female) having the FGF23-R176Q mutation were enrolled; five completed the 12-month protocol. At baseline three of five subjects had severely symptomatic hypophosphatemia (phosphorus <2.5 mg/dL) and received calcitriol with or without phosphate concurrent with oral iron during the trial. The primary outcome was met by 4 of 5 (80%) subjects all by month 4, and 5 of 5 had normal intact FGF23 at month 12. Median (minimum, maximum) intact FGF23 concentration decreased from 172 (20, 192) pg/mL at baseline to 47 (17, 78) pg/mL at month 4 and 42 (19, 63) pg/mL at month 12. Median ferritin increased from 18.6 (7.7, 82.5) ng/mL at baseline to 78.0 (49.6, 261.0) ng/mL at month 12. During iron treatment, all three subjects with baseline hypophosphatemia normalized serum phosphorus, had markedly improved symptoms, and were able to discontinue calcitriol and phosphate. Oral iron repletion normalized FGF23 and phosphorus in symptomatic, iron-deficient ADHR subjects. Thus, the standard approach to ADHR should include recognition, treatment, and prevention of iron deficiency. © 2019 American Society for Bone and Mineral Research. SN - 1523-4681 UR - https://www.unboundmedicine.com/medline/citation/31652009/Oral_Iron_Replacement_Normalizes_Fibroblast_Growth_Factor_23_in_Iron_Deficient_Patients_With_Autosomal_Dominant_Hypophosphatemic_Rickets_ L2 - https://doi.org/10.1002/jbmr.3878 DB - PRIME DP - Unbound Medicine ER -