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Braithwaite VS, Mwangi MN, Jones KS, Demir AY, Prentice A, Prentice AM, Andang'o PEA, Verhoef H. Antenatal iron supplementation, FGF23, and bone metabolism in Kenyan women and their offspring: secondary analysis of a randomized controlled trial. Am J Clin Nutr 2021; 113:1104-1114. [PMID: 33675347 PMCID: PMC8106766 DOI: 10.1093/ajcn/nqaa417] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 12/10/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Fibroblast growth factor-23 (FGF23) regulates body phosphate homeostasis primarily by increasing phosphaturia. It also acts as a vitamin D-regulating hormone. Maternal iron deficiency is associated with perturbed expression and/or regulation of FGF23 and hence might be implicated in the pathogenesis of hypophosphatemia-driven rickets in their offspring. OBJECTIVES We aimed to determine the effect of antenatal oral iron supplementation on FGF23 concentration and maternal and infant markers of bone-mineral regulation. METHODS We performed a secondary analysis of a trial in which 470 rural Kenyan women with singleton pregnancies and hemoglobin concentrations ≥ 90 g/L were randomly allocated to daily, supervised supplementation with 60 mg elemental iron as ferrous fumarate or placebo from 13-23 weeks of gestation until 1 mo postpartum. As previously reported, iron supplementation improved iron status in mothers and neonates. For the present study, we reanalyzed all available plasma samples collected in mothers and neonates at birth, with primary outcomes being concentrations of FGF23, measured by 2 assays: 1 that detects intact hormone and C-terminal cleavage products (total-FGF23) and another that detects the intact hormone only (intact-FGF23). RESULTS Analysis was performed on 433 women (n = 216, iron group; n = 217, placebo group) and 414 neonates (n = 207, iron group; n = 207, placebo group). Antenatal iron supplementation reduced geometric mean total-FGF23 concentrations in mothers and neonates by 62.6% (95% CI: 53.0%, 70.3%) and 15.2% (95% CI: -0.3%, 28.4%, P = 0.06), respectively. In addition, it increased geometric mean neonatal intact-FGF23 concentrations by 21.6% (95% CI: 1.2%, 46.1%), increased geometric mean maternal hepcidin concentrations by 136.4% (95% CI: 86.1%, 200.3%), and decreased mean maternal 25-hydroxyvitamin D concentrations by 6.1 nmol/L (95% CI: -11.0, -1.2 nmol/L). CONCLUSIONS Analysis of this randomized trial confirms that iron supplementation can reverse elevated FGF23 production caused by iron deficiency in iron-deficient mothers and their neonates. Further investigations are warranted to assess to what extent iron supplementation can prevent FGF23-mediated hypophosphatemic rickets or osteomalacia.
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Affiliation(s)
| | - Martin N Mwangi
- Wageningen University, Division of Human Nutrition and Health, P.O. Box 17, 6700 AA Wageningen, The Netherlands,University of Malawi, College of Medicine, Training and Research Unit of Excellence, Private Bag 360, BT 3, Chichiri, Blantyre, Malawi
| | - Kerry S Jones
- National Institute for Health Research (NIHR) Biomedical Research Centre Nutritional Biomarker Laboratory, MRC Epidemiology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0AH, United Kingdom
| | - Ayşe Y Demir
- Meander Medical Centre, Laboratory for Clinical Chemistry and Hematology, P.O. Box 1502, 3800 BM Amersfoort, The Netherlands
| | - Ann Prentice
- Medical Research Council (MRC) Nutrition and Bone Health Research Group, Clifford Allbutt Building, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0AH, United Kingdom (formerly the MRC Elsie Widdowson Laboratory, 120 Fulbourn Road, Cambridge, CB1 9NL, United Kingdom),Medical Research Council (MRC) Unit The Gambia at London School of Hygiene & Tropical Medicine, Atlantic Boulevard, Fajara, Banjul, The Gambia
| | - Andrew M Prentice
- Medical Research Council (MRC) Unit The Gambia at London School of Hygiene & Tropical Medicine, Atlantic Boulevard, Fajara, Banjul, The Gambia
| | - Pauline E A Andang'o
- Maseno University, School of Public Health and Community Development, Maseno, Kenya
| | - Hans Verhoef
- Wageningen University, Division of Human Nutrition and Health, P.O. Box 17, 6700 AA Wageningen, The Netherlands,Wageningen University, Cell Biology and Immunology Group, P.O. Box 338, 6708 WD Wageningen, The Netherlands
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Naveh-Many T, Volovelsky O. Parathyroid Cell Proliferation in Secondary Hyperparathyroidism of Chronic Kidney Disease. Int J Mol Sci 2020; 21:ijms21124332. [PMID: 32570711 PMCID: PMC7352987 DOI: 10.3390/ijms21124332] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 06/14/2020] [Accepted: 06/15/2020] [Indexed: 12/12/2022] Open
Abstract
Secondary hyperparathyroidism (SHP) is a common complication of chronic kidney disease (CKD) that correlates with morbidity and mortality in uremic patients. It is characterized by high serum parathyroid hormone (PTH) levels and impaired bone and mineral metabolism. The main mechanisms underlying SHP are increased PTH biosynthesis and secretion as well as increased glandular mass. The mechanisms leading to parathyroid cell proliferation in SHP are not fully understood. Reduced expressions of the receptors for calcium and vitamin D contribute to the disinhibition of parathyroid cell proliferation. Activation of transforming growth factor-α-epidermal growth factor receptor (TGF-α-EGFR), nuclear factor kappa B (NF-kB), and cyclooxygenase 2- prostaglandin E2 (Cox2-PGE2) signaling all correlate with parathyroid cell proliferation, underlining their roles in the development of SHP. In addition, the mammalian target of rapamycin (mTOR) pathway is activated in parathyroid glands of experimental SHP rats. Inhibition of mTOR by rapamycin prevents and corrects the increased parathyroid cell proliferation of SHP. Mice with parathyroid-specific deletion of all miRNAs have a muted increase in serum PTH and fail to increase parathyroid cell proliferation when challenged by CKD, suggesting that miRNA is also necessary for the development of SHP. This review summarizes the current knowledge on the mechanisms of parathyroid cell proliferation in SHP.
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Affiliation(s)
- Tally Naveh-Many
- Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew University Medical Center, Jerusalem 91120, Israel;
- The Wohl Institute for Translational Medicine, Hadassah Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Oded Volovelsky
- The Wohl Institute for Translational Medicine, Hadassah Hebrew University Medical Center, Jerusalem 91120, Israel
- Pediatric Nephrology Unit and Research Lab, Hadassah Hebrew University Medical Center, Jerusalem 91120, Israel
- Correspondence: ; Tel.: +972-26777213
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