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Struppe A, Schanda JE, Baierl A, Watzl P, Muschitz C. Impact of Intravenous Iron Substitution on Serum Phosphate Levels and Bone Turnover Markers-An Open-Label Pilot Study. Nutrients 2023; 15:2693. [PMID: 37375595 DOI: 10.3390/nu15122693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
The association between intravenous iron substitution therapy and hypophosphatemia was previously reported in patients with iron deficiency anemia. However, the extent of hypophosphatemia is thought to depend on the type of iron supplementation. We hypothesized that the intravenous application of ferric carboxymaltose and iron sucrose leads to a different longitudinal adaptation in serum phosphate levels. In this open-label pilot study, a total of 20 patients with inflammatory bowel diseases or iron deficiency anemia were randomly assigned to one of two study groups (group 1: ferric carboxymaltose, n = 10; group 2: iron sucrose, n = 10). Serum values were controlled before iron substitution therapy, as well as 2, 4, and 12 weeks after the last drug administration. The primary objective of the study was the longitudinal evaluation of serum phosphate levels after iron substitution therapy with ferric carboxymaltose and iron sucrose. The secondary objective was the longitudinal investigation of calcium, 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone, procollagen type 1 amino-terminal propeptide (P1NP), beta-CrossLaps (CTX), hemoglobin (Hb), iron, ferritin, and transferrin saturation levels. Two weeks after drug administration, phosphate levels were significantly lower (p < 0.001) in group 1 and ferritin levels were significantly higher (p < 0.001) in group 1. Phosphate levels (0.8-1.45 mmol/L) were below the therapeutic threshold and ferritin levels (10-200 ng/mL for women and 30-300 ng/mL for men) were above the therapeutic threshold in group 1. P1NP (15-59 µg/L) and CTX (<0.57 ng/mL) levels were above the therapeutic threshold in group 2. Four weeks after drug administration, significant differences were still observed between both study groups for phosphate (p = 0.043) and ferritin (p = 0.0009). All serum values except for Hb were within the therapeutic thresholds. Twelve weeks after drug administration, no differences were observed in all serum values between both study groups. Hb values were within the therapeutic threshold in both study groups. Serum 25(OH)D levels did not differ between both study groups throughout the whole study period and remained within the therapeutic threshold.
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Affiliation(s)
- Alexandra Struppe
- St. Vincent Hospital Vienna, II Medical Department-Gastroenterology, Hepatology, Metabolic, and Inflammation Medicine, Academic Teaching Hospital of the Medical University of Vienna, 1060 Vienna, Austria
| | - Jakob E Schanda
- AUVA Trauma Center Vienna-Meidling, Department for Trauma Surgery, 1120 Vienna, Austria
- Ludwig Boltzmann Institute for Traumatology, 1200 Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1200 Vienna, Austria
| | - Andreas Baierl
- Insitute for Statistics and Operations Research, University of Vienna, 1090 Vienna, Austria
| | - Paul Watzl
- St. Vincent Hospital Vienna, II Medical Department-Gastroenterology, Hepatology, Metabolic, and Inflammation Medicine, Academic Teaching Hospital of the Medical University of Vienna, 1060 Vienna, Austria
| | - Christian Muschitz
- St. Vincent Hospital Vienna, II Medical Department-Gastroenterology, Hepatology, Metabolic, and Inflammation Medicine, Academic Teaching Hospital of the Medical University of Vienna, 1060 Vienna, Austria
- HealthPi Medical Center, 1010 Vienna, Austria
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Severe Hypophosphatemia Occurring After Repeated Exposure to a Parenteral Iron Formulation. Case Rep Endocrinol 2022; 2022:1011401. [PMID: 36248222 PMCID: PMC9568323 DOI: 10.1155/2022/1011401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/12/2022] [Indexed: 11/16/2022] Open
Abstract
Hypophosphatemia is a less known complication of parenteral iron use, particularly after the use of certain iron formulations. We report the case of a young male with inflammatory bowel disease and iron deficiency anemia, who developed severe symptomatic hypophosphatemia after his third exposure to iron carboxymaltose with no evidence of the same occurring upon prior exposures to the compound. Investigations revealed serum phosphorous levels of 0.7 mg/dl, corrected serum calcium of 8-9.5 mg/dl, alkaline phosphatase of 50 U/L (38-126), 25 hydroxy vitamin D level of 40.2 ng/ml, and intact PTH elevated to 207 pg/ml. Urine studies indicated renal phosphate wasting. Presentation was not in keeping with refeeding syndrome. Intact fibroblast growth factor 23 level, measured after the initiation of treatment was within the normal range at 179 RU/mL (44-215). 1,25 dihydroxy vitamin D level, also measured after the initiation of treatment, was normal at 26.3 pg/ml (19.9-79.3). The patient was treated with calcitriol and aggressive oral and intravenous phosphorous repletion. Symptoms then resolved and the patient was discharged on an oral regimen. This phenomenon is postulated to occur due to an increase in the level and activity of FGF23 and decreased cleavage of the same, due to anemia as well as use of specific iron formulations. This is the first instance, in our literature review, of this complication known to occur, not after initial exposure to an implicated iron formulation but occurring on subsequent exposure.
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Boots JMM, Quax RAM. High-Dose Intravenous Iron with Either Ferric Carboxymaltose or Ferric Derisomaltose: A Benefit-Risk Assessment. Drug Saf 2022; 45:1019-1036. [PMID: 36068430 PMCID: PMC9492608 DOI: 10.1007/s40264-022-01216-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2022] [Indexed: 11/22/2022]
Abstract
The intravenous iron formulations ferric carboxymaltose (FCM) and ferric derisomaltose (FDI) offer the possibility of administering a large amount of iron in one infusion. This results in faster correction of anemia and the formulations being better tolerated than oral iron formulations. This triad of logistic advantages, improved patient convenience, and fast correction of anemia explains the fact that intravenous iron formulations nowadays are frequently prescribed worldwide in the treatment of iron deficiency anemia. However, these formulations may result in hypophosphatemia by inducing a strong increase in active fibroblast growth factor-23 (FGF-23), a hormone that stimulates renal phosphate excretion. This effect is much more pronounced with FCM than with FDI, and therefore the risk of developing hypophosphatemia is remarkably higher with FCM than with FDI. Repeated use of FCM may result in severe osteomalacia, which is characterized by bone pain, Looser zones (pseudofractures), and low-trauma fractures. Intravenous iron preparations are also associated with other adverse effects, of which hypersensitivity reactions are the most important and are usually the result of a non-allergic complement activation on nanoparticles of free labile iron-Complement Activation-Related Pseudo-Allergy (CARPA). The risk on these hypersensitivity reactions can be reduced by choosing a slow infusion rate. Severe hypersensitivity reactions were reported in < 1% of prospective trials and the incidence seems comparable between the two formulations. A practical guideline has been developed based on baseline serum phosphate concentrations and predisposing risk factors, derived from published cases and risk factor analyses from trials, in order to establish the safe use of these formulations.
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Affiliation(s)
- Johannes M M Boots
- Department of Internal Medicine, Maasstad Hospital, Maasstadweg 21, 3079 DZ, Rotterdam, The Netherlands.
| | - Rogier A M Quax
- Department of Internal Medicine, Maasstad Hospital, Maasstadweg 21, 3079 DZ, Rotterdam, The Netherlands
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Vilaca T, Velmurugan N, Smith C, Abrahamsen B, Eastell R. Osteomalacia as a Complication of Intravenous Iron Infusion: A Systematic Review of Case Reports. J Bone Miner Res 2022; 37:1188-1199. [PMID: 35426179 PMCID: PMC9322686 DOI: 10.1002/jbmr.4558] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/18/2022] [Accepted: 04/08/2022] [Indexed: 12/05/2022]
Abstract
Randomized control trials (RCTs) have shown that certain intravenous iron preparations can induce high levels of fibroblast growth factor 23 (FGF-23) and persistent hypophosphatemia. Repeated iron infusions may lead to prolonged hypophosphatemia and osteomalacia events not captured by RCTs. Several previous case reports have described skeletal adverse effects after repeated iron infusions. To characterize these effects, we conducted a systematic review of case reports. MEDLINE, Embase, Web of Science, and Cochrane databases were searched in March 2021. We selected case reports of patients ≥16 years old. Study quality was assessed using the tool from Murad and colleagues. We report the results in a narrative summary. We identified 28 case reports, reporting 30 cases. Ages ranged from 28 to 80 years (median 50 years). Most patients (n = 18) received ferric carboxymaltose (FCM), whereas 8 received saccharated ferric oxide (SFO) and 3 received iron polymaltose (IPM). All but 2 cases had more than five infusions (range 2 to 198, median 17). The lowest phosphate levels ranged from 0.16 to 0.77 mmol/L (median 0.36 mmol/L). Intact FGF-23 (iFGF-23) was high when measured. Serum 25OH vitamin D was low in 10 of 21 cases measured and 1,25(OH)2 vitamin D in 12 of 18. Alkaline phosphatase was high in 18 of 22 cases. Bone or muscle pain was reported in 28 of the 30 cases. Twenty patients had pseudofractures, 9 had fractures, and 6 patients had both. All 15 available bone scans showed focal isotope uptake. Case reports tend to report severe cases, so potential reporting bias should be considered. Osteomalacia is a potential complication of repeated iron infusion, especially in patients with gastrointestinal disorders receiving prolonged therapy. Pain and fractures or pseudofractures are common clinical findings, associated with low phosphate, high iFGF-23, high alkaline phosphatase, and abnormal isotope bone scan. Discontinuing or switching the iron formulation was an effective intervention in most cases. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Tatiane Vilaca
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | | | - Christopher Smith
- Open Patient Data Explorative Network, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Bo Abrahamsen
- Department of Medicine, Holbaek Hospital, Holbaek, Denmark.,Open Patient Data Explorative Network, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Denmark and NDORMS, University of Oxford, Oxford, UK
| | - Richard Eastell
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
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Schaefer B, Tobiasch M, Wagner S, Glodny B, Tilg H, Wolf M, Zoller H. Hypophosphatemia after intravenous iron therapy: Comprehensive review of clinical findings and recommendations for management. Bone 2022; 154:116202. [PMID: 34534708 DOI: 10.1016/j.bone.2021.116202] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/06/2021] [Accepted: 09/10/2021] [Indexed: 12/19/2022]
Abstract
Contemporary intravenous iron formulations allow administration of high doses of elemental iron and enable correction of total iron deficit in one or two infusions. An important but underappreciated complication of certain formulations is hypophosphatemia caused by increased secretion of the phosphaturic hormone, fibroblast growth factor 23 (FGF23). The pathophysiology of FGF23-induced hypophosphatemia due to certain intravenous iron formulations has been recently investigated in prospective clinical trials. To reach the correct diagnosis, clinicians must recognize the typical clinical manifestations of intravenous iron-induced hypophosphatemia and identify a specific pattern of biochemical changes (hyperphosphaturic hypophosphatemia triggered by high FGF23 that causes low 1,25 (OH)2 vitamin D, hypocalcemia and secondary hyperparathyroidism). Physicians and patients should be aware of hypophosphatemia as a common complication of intravenous iron therapy and monitor serum phosphate concentrations in patients receiving repeated doses of specific intravenous iron formulations. Symptoms of hypophosphatemia are associated with severity and duration. Persistent hypophosphatemia can occur with iron therapy and can cause debilitating diseases including myopathy, osteomalacia and fractures. This review summarizes the current understanding of the iron-phosphate axis as well as complications of intravenous iron-induced hypophosphatemia.
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Affiliation(s)
- Benedikt Schaefer
- Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Hepatology and Endocrinology, Innsbruck, Austria; Christian Doppler Laboratory on Iron and Phosphate Biology, Austria
| | - Moritz Tobiasch
- University Teaching Hospital of Hall in Tirol, Department of Medicine, Hall, Austria
| | - Sonja Wagner
- Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Hepatology and Endocrinology, Innsbruck, Austria; Christian Doppler Laboratory on Iron and Phosphate Biology, Austria
| | - Bernhard Glodny
- Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Herbert Tilg
- Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Hepatology and Endocrinology, Innsbruck, Austria
| | - Myles Wolf
- Department of Medicine, Division of Nephrology, Duke University, Durham, NC, United States of America
| | - Heinz Zoller
- Medical University of Innsbruck, Department of Medicine I, Gastroenterology, Hepatology and Endocrinology, Innsbruck, Austria; Christian Doppler Laboratory on Iron and Phosphate Biology, Austria.
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Ali A, Elmdaah A, Mustafa AM, Kumaravel Kanagavelu AS, Mohamed N, Sayed S. Severe Hypophosphatemia Following Ferric Carboxymaltose in a Patient With Inflammatory Bowel Disease. Cureus 2021; 13:e20452. [PMID: 35047286 PMCID: PMC8760031 DOI: 10.7759/cureus.20452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2021] [Indexed: 11/05/2022] Open
Abstract
Inflammatory bowel disease is a chronic inflammatory condition that affects the large and small bowel, which includes Crohn’s disease (CD) and ulcerative colitis (UC). Iron deficiency anemia (IDA) is one of the most common complications in people with inflammatory bowel disease. The treatment of choice is intravenous iron infusion. There is a lack of awareness of side effects of intravenous iron (Ferinject) such as hypophosphatemia, which can prolong hospital admission. We present the case of a patient with iron deficiency anemia and vitamin D deficiency who developed severe hypophosphatemia after intravenous injection of ferric carboxymaltose (Ferinject). In this case presentation, our aim is to increase the awareness of prescribers about the risk of developing low phosphate levels after Ferinject and the need to monitor serum phosphate levels.
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Glaspy JA, Wolf M, Strauss WE. Intravenous Iron-Induced Hypophosphatemia: An Emerging Syndrome. Adv Ther 2021; 38:3531-3549. [PMID: 34053011 PMCID: PMC8279965 DOI: 10.1007/s12325-021-01770-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 04/30/2021] [Indexed: 12/14/2022]
Abstract
Some, but not all, intravenous iron formulations have been recognized to induce renal phosphate wasting syndrome. Most commonly this has been reported following treatment of iron deficiency anemia (IDA) with ferric carboxymaltose (FCM). A search of PubMed identified relevant randomized controlled trials (RCTs), and case studies evaluating hypophosphatemia (HPP) resulting from intravenous iron treatment. While more recent larger comparative RCTs have confirmed that the majority of patients receiving FCM, especially those with normal renal function, may experience severe HPP, complete documentation is hampered by inconsistent reporting of serum phosphate in such trials. Similarly, while case series and RCTs have documented the persistence of HPP for several weeks or even months, the lack of studies lasting beyond 5–6 weeks has constrained full understanding of the duration of effect. Clinical trials have established that the mechanism involves the bone/metabolic axis with the elevation of intact fibroblast growth factor 23 playing the central role. Reports continue to accumulate of the clinical consequences of severe HPP which are, most commonly, bone abnormalities following repetitive dosing. Case reports and studies, however, have also shown that symptomatic hypophosphatemia can occur after a single FCM dose. The frequency of such events remains unknown, in part due to lack of awareness of hypophosphatemia coupled with the fact that the most common acute symptoms of HPP (fatigue and weakness) are the same for IDA and for many of the chronic diseases that cause IDA. Changes to US and European prescribing information for FCM should raise awareness of the potential for HPP and need to monitor patients at risk for it.
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Affiliation(s)
- John A Glaspy
- Division of Hematology-Oncology, Department of Medicine, UCLA School of Medicine, Los Angeles, CA, 90095, USA.
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
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Kalantar‐Zadeh K, Ganz T, Trumbo H, Seid MH, Goodnough LT, Levine MA. Parenteral iron therapy and phosphorus homeostasis: A review. Am J Hematol 2021; 96:606-616. [PMID: 33471363 PMCID: PMC8248123 DOI: 10.1002/ajh.26100] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/13/2021] [Accepted: 01/17/2021] [Indexed: 12/16/2022]
Abstract
Phosphorus has an essential role in cellular and extracellular metabolism; maintenance of normal phosphorus homeostasis is critical. Phosphorus homeostasis can be affected by diet and certain medications; some intravenous iron formulations can induce renal phosphate excretion and hypophosphatemia, likely through increasing serum concentrations of intact fibroblast growth factor 23. Case studies provide insights into two types of hypophosphatemia: acute symptomatic and chronic hypophosphatemia, while considering the role of pre‐existing conditions and comorbidities, medications, and intravenous iron. This review examines phosphorus homeostasis and hypophosphatemia, with emphasis on effects of iron deficiency and iron replacement using intravenous iron formulations.
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Affiliation(s)
- Kamyar Kalantar‐Zadeh
- Division of Nephrology and Hypertension and Kidney Transplantation University of California Irvine Orange California USA
| | - Tomas Ganz
- David Geffen School of Medicine University of California, Los Angeles Los Angeles California USA
| | - Henry Trumbo
- St. Mary Medical Center Langhorne Pennsylvania USA
| | - Melvin H. Seid
- Department of Obstetrics and Gynecology University of Southern California Verdugo Hills Hospital Glendale California USA
| | | | - Michael A. Levine
- Center for Bone Health and Division of Endocrinology and Diabetes Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine Philadelphia Pennsylvania USA
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Lecoq AL, Dong C, Carbonnel F, Becquemont L. [Hypophosphatemia following the administration of intravenous iron formulations: A case report and literature review]. Therapie 2021; 76:705-714. [PMID: 33962799 DOI: 10.1016/j.therap.2021.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/23/2021] [Accepted: 04/13/2021] [Indexed: 12/21/2022]
Abstract
Iron deficiency and iron-deficiency anemia are common medical conditions. Management of the etiology and iron supplementation are both necessary to treat this condition. Use of intravenous iron preparations is increasing due to its advantages over oral iron. Indeed, the total dose required can be provided in a single infusion, and it is more effective and increases hemoglobin levels more quickly than oral iron. Hypophosphatemia, sometimes severe, following intravenous iron administration, has been described in literature these past years, in particular with ferric carboxymaltose. We report here a case of severe hypophosphatemia with ferric carboxymaltose and carry out a literature review to determine the incidence of hypophosphatemia and to precise its clinical presentation, its pathophysiological mechanisms and its treatment. We found that hypophosphatemia is frequent with ferric carboxymaltose. Most of the time, there are no clinical manifestations, but cases of symptomatic osteomalacia have been described. Duration of hypophosphatemia is variable, from a few weeks to several months in case of prolonged administration. Hypophosphatemia owing to renal phosphate wasting is caused by an increase in intact fibroblast growth factor 23 (FGF-23) levels. However, the mechanism of ferric carboxymaltose- induced increase in intact FGF-23 is still unknown.
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Affiliation(s)
- Anne-Lise Lecoq
- Assistance publique-Hôpitaux de Paris (AP-HP), hôpital Bicêtre, Centre de Recherche Clinique AP-HP, université Paris-Saclay, 78, rue du Général-Leclerc, 94270 Le Kremlin-Bicêtre, France.
| | - Catherine Dong
- Service de Gastro-Entérologie, Assistance publique-Hôpitaux de Paris (AP-HP), hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - Franck Carbonnel
- Service de Gastro-Entérologie, Assistance publique-Hôpitaux de Paris (AP-HP), hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - Laurent Becquemont
- Assistance publique-Hôpitaux de Paris (AP-HP), hôpital Bicêtre, Centre de Recherche Clinique AP-HP, université Paris-Saclay, 78, rue du Général-Leclerc, 94270 Le Kremlin-Bicêtre, France
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Frazier R, Hodakowski A, Cai X, Lee J, Zakarija A, Stein B, David V, Wolf M, Isakova T, Mehta R. Effects of ferric carboxymaltose on markers of mineral and bone metabolism: A single-center prospective observational study of women with iron deficiency. Bone 2020; 141:115559. [PMID: 32730929 PMCID: PMC7680361 DOI: 10.1016/j.bone.2020.115559] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 06/03/2020] [Accepted: 07/07/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Two weekly infusions of ferric carboxymaltose (FCM) are commonly prescribed for treatment of iron-deficiency anemia. However, administration of FCM increases intact levels of fibroblast growth factor 23 (FGF23), which causes hypophosphatemia due to renal phosphate wasting, calcitriol deficiency and secondary hyperparathyroidism. The adverse effects of FCM on mineral metabolism and bone health emerged from case reports and secondary analyses of trials. Data on these safety signals with FCM in clinical practice are limited because markers of mineral and bone metabolism are not routinely checked. METHODS To obtain real-world experience with effects of FCM on mineral and bone metabolism, we conducted a prospective observational study of 16 women who were managed at a single-center hematology clinic for iron-deficiency anemia. From October 2016 to February 2018, all participants received two weekly infusions of FCM at a hematology infusion clinic. We hypothesized that FCM would decrease phosphate, increase intact FGF23 (iFGF23), and decrease c-terminal FGF23 (cFGF23). Secondary outcomes were changes in hemoglobin, iron indices, urine fractional excretion of phosphate (FePi), parathyroid hormone (PTH), calcitriol, calcium, osteocalcin, and bone-specific alkaline phosphatase (BAP). FCM was administered at weeks zero and one, and we measured laboratory values at weeks zero, one, two, and five of the study. We used linear mixed models to analyze the significance of the changes in laboratory values over time. RESULTS After two FCM infusions, nearly all (14 of 16) participants developed hypophosphatemia. iFGF23 increased, cFGF23 decreased, and phosphate decreased significantly from week zero to week two (iFGF23 increased by +134.0% [40.6, 305.8], p < 0.001; cFGF23 decreased by -516.3% [-1332.7, -142.7], p = 0.002; phosphate decreased by -49.8 ± 15.4%, p < 0.001). There was also a significant increase in FePi, PTH, and BAP and a significant decrease in calcitriol and calcium from week zero to week two. There was no significant change in osteocalcin during this time period. iFGF23, but not PTH, was independently associated with decreased phosphate. iFGF23 was also significantly associated with decrease in calcitriol from week zero to week two. Elevation in BAP suggests disordered bone mineralization in response to FCM therapy. CONCLUSION In this prospective observational study of women with iron deficiency anemia, two FCM infusions significantly altered markers of bone mineralization and mineral metabolism. The results suggest that FCM should be used cautiously in the treatment of iron-deficiency anemia.
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Affiliation(s)
- Rebecca Frazier
- Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Jesse Brown Veterans Administration Medical Center, Chicago, IL 60612, USA.
| | - Alexander Hodakowski
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Xuan Cai
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jungwha Lee
- Division of Biostatistics, Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Anaadriana Zakarija
- Division of Hematology/Oncology, Robert H. Lurie Comprehensive Cancer Center, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Brady Stein
- Division of Hematology/Oncology, Robert H. Lurie Comprehensive Cancer Center, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Valentin David
- Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC 27701, USA
| | - Tamara Isakova
- Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Rupal Mehta
- Division of Nephrology and Hypertension, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Jesse Brown Veterans Administration Medical Center, Chicago, IL 60612, USA
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A Pooled Analysis of Serum Phosphate Measurements and Potential Hypophosphataemia Events in 45 Interventional Trials with Ferric Carboxymaltose. J Clin Med 2020; 9:jcm9113587. [PMID: 33172157 PMCID: PMC7694774 DOI: 10.3390/jcm9113587] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 12/20/2022] Open
Abstract
Ferric carboxymaltose (FCM) has been shown to achieve rapid replenishment of iron stores and correction of anaemia in various populations with iron deficiency. A decrease in serum phosphate (PO43−) levels, which in most cases is asymptomatic, has been reported with IV iron preparations. Hypophosphataemia (HP) is a known adverse drug reaction with FCM. This post hoc pooled analysis investigates the frequency, duration, risk factors, and clinical signs of HP as reported in interventional clinical trials with FCM. Pooled data from subjects enrolled across 45 clinical trials in different therapy areas were included. A three-step adjudication process was utilised to identify adverse events of HP. Stratified analyses by therapy group and stepwise logistic regression analysis were used to identify predictors of HP. This pooled analysis confirms that FCM is associated with increased rates of serum PO43− lowering, but mean serum PO43− values were seen to recover at Week 4 and further recover at Week 8. Among all subjects receiving FCM therapy (n = 6879), 41.4% (n = 2847) reached a PO43− nadir value <2.5 mg/dL at any point on study and 0.7% (n = 49) reached a nadir <1 mg/dL. Although gastroenterology and women’s health subjects were identified to be at higher risk, occurrence of severe HP (<1 mg/dL [0.3 mmol/L]) following FCM administration was not observed to be common among subjects in these studies. Furthermore, there was no correlation between laboratory serum PO43− values and the occurrence of reported adverse events related to low PO43− levels.
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Cundy T, Que L, Hassan IM, Hughes L. Bisphosphonate-Induced Deterioration of Osteomalacia in Undiagnosed Adult Fanconi Syndrome. JBMR Plus 2020; 4:e10374. [PMID: 32803107 PMCID: PMC7422711 DOI: 10.1002/jbm4.10374] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/28/2020] [Accepted: 05/26/2020] [Indexed: 12/16/2022] Open
Abstract
We describe two women with a misdiagnosed fracturing bone disease who were treated erroneously with i.v. zoledronate. Over the next year, they suffered marked clinical and radiographic deterioration in skeletal disease. Both were eventually diagnosed with hypophosphatemic osteomalacia secondary to acquired Fanconi syndrome (caused by light-chain myeloma in one case and tenofovir treatment in the other). Appropriate treatment with phosphate supplementation was instituted with clinical improvement. These cases illustrate the importance of not missing osteomalacia in adults presenting with fractures, and the potentially damaging effects of treatment with long-acting inhibitors of bone resorption in these circumstances. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Tim Cundy
- Department of Endocrinology Greenlane Clinical Centre Auckland New Zealand
| | - Lorna Que
- Nuclear Medicine, Department of Radiology Auckland City Hospital Auckland New Zealand
| | - Ibrahim M Hassan
- Nuclear Medicine, Department of Radiology Auckland City Hospital Auckland New Zealand
| | - Louise Hughes
- Department of Anatomical Pathology Concord Hospital Sydney Australia
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13
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Glaspy JA, Lim-Watson MZ, Libre MA, Karkare SS, Hadker N, Bajic-Lucas A, Strauss WE, Dahl NV. Hypophosphatemia Associated with Intravenous Iron Therapies for Iron Deficiency Anemia: A Systematic Literature Review. Ther Clin Risk Manag 2020; 16:245-259. [PMID: 32308402 PMCID: PMC7152545 DOI: 10.2147/tcrm.s243462] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 03/06/2020] [Indexed: 12/11/2022] Open
Abstract
Background Iron deficiency anemia (IDA) is a prevalent yet underdiagnosed condition with a significant impact on quality of life. Oral iron supplementation is often poorly tolerated or yields inadequate response, requiring the use of intravenous iron (IVI) in some patients. Administration of certain IVI preparations has been associated with decreases in serum phosphate levels and clinically significant hypophosphatemia, which has been reported to lead to adverse events including serious fatigue and osteomalacia. Objective The purpose of this study was to systematically assess the prevalence, clinical consequences, and reporting of treatment-emergent hypophosphatemia within literature investigating IVI therapies marketed in the United States (US). Methods A systematic literature review (SLR) was conducted using the PubMed database to identify publications reporting serum phosphate levels or rates of hypophosphatemia within adult IDA patient populations receiving current US-marketed IVIs. Results The SLR yielded 511 unique publications, with 40 records meeting the final inclusion criteria. Most studies did not report phosphate monitoring methodology or an explicit definition of hypophosphatemia. Hypophosphatemia rates ranged from 0.0% to 92.1% for ferric carboxymaltose (FCM), 0.0% to 40.0% for iron sucrose, 0.4% for ferumoxytol, and 0.0% for low-molecular-weight (LMW) iron dextran. Randomized controlled studies described hypophosphatemia as “asymptomatic” or did not report on other associated sequelae. Eleven case reports detailed treatment-emergent hypophosphatemia in patients treated with FCM. Patients with acute hypophosphatemia primarily developed severe fatigue; those with repeated FCM dosing developed chronic hypophosphatemia associated with osteomalacia and bone deformities. Conclusion Studies analyzed in this SLR reported a range of hypophosphatemia rates, with the highest consistently seen in patients treated with FCM. Across the clinical literature, there appeared to be minimal standardization of phosphate monitoring and definitions of hypophosphatemia. Although multiple cases have documented serious clinical consequences of hypophosphatemia associated with certain IVIs, current trials neither consistently nor adequately assess the frequency and severity of treatment-emergent hypophosphatemia and may underestimate its prevalence.
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14
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Babitt JL, Sitara D. Crosstalk between fibroblast growth factor 23, iron, erythropoietin, and inflammation in kidney disease. Curr Opin Nephrol Hypertens 2020; 28:304-310. [PMID: 31145704 PMCID: PMC6693648 DOI: 10.1097/mnh.0000000000000514] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Recent research has revealed that regulation of the bone-secreted hormone fibroblast growth factor 23 (FGF23) is not limited to classical mineral factors. Specifically, bidirectional relationships have been described between FGF23 production and anemia, iron status, and inflammation. Here, we will review the latest published articles on the crosstalk between FGF23 and the aforementioned nonclassical factors. RECENT FINDINGS It has been recently reported that erythropoietin, iron deficiency, and inflammation increase FGF23 production and metabolism. Moreover, FGF23 promotes anemia and regulates inflammatory responses. These findings are particularly important in the setting of chronic kidney disease which is characterized by elevated FGF23 levels and several associated comorbidities. SUMMARY Regulation of FGF23 is complex and involves many bone and renal factors. More recently, erythropoietin, iron deficiency, and inflammation have been also shown to affect FGF23 transcription and cleavage. Importantly, FGF23 has emerged as a regulator of erythropoiesis, iron metabolism, and inflammation. These findings provide novel and important insights into the pathophysiologic mechanisms of chronic kidney disease and may present new opportunities for therapeutic clinical interventions.
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Affiliation(s)
- Jodie L Babitt
- Department of Medicine, Division of Nephrology, Program in Membrane Biology, Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Despina Sitara
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry.,Department of Medicine, New York University School of Medicine, New York, New York, USA
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15
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Schoeb M, Räss A, Frei N, Aczél S, Brändle M, Bilz S. High Risk of Hypophosphatemia in Patients with Previous Bariatric Surgery Receiving Ferric Carboxymaltose: A Prospective Cohort Study. Obes Surg 2020; 30:2659-2666. [PMID: 32221822 DOI: 10.1007/s11695-020-04544-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Iron deficiency is a common finding in patients with previous bariatric surgery, and parenteral supplementation is frequently required. Ferric carboxymaltose (FCM) is among the preferred compounds used but may be associated with new-onset hypophosphatemia. This study was undertaken to study the prevalence of hypophosphatemia following FCM in patients with previous bariatric surgery, a population that may be at particular risk due to highly prevalent secondary hyperparathyroidism. METHODS Patients with previous bariatric surgery and iron depletion scheduled for FCM infusion were prospectively studied before and one week after FCM application. The primary endpoint was new-onset hypophosphatemia. Patients were followed until plasma phosphate had normalized without replacement. RESULTS Fifty-two patients (40 females) following Roux-en-Y gastric bypass (n = 50) or sleeve gastrectomy (n = 2), with a median age of 46 years (range 22-68) and a BMI of 32.2 kg/m2 (27.5-37.3), were analyzed. Fifteen patients (29%) developed new-onset hypophosphatemia, with 11 (21%) requiring oral phosphate supplementation for a median duration of 14 days (14-25). The plasma phosphate decreased by 0.3 mmol/l (-0.5--0.2; p < 0.001) secondary to a 56% increase in the fractional urinary phosphate excretion (p < 0.001). This was associated with a significant increase in serum intact FGF23 (+30%; p < 0.001) and a decrease in serum 1,25(OH)2 vitamin D3 concentrations (-37.6%; p < 0.001). CONCLUSION Patients with previous bariatric surgery receiving FCM are at considerable risk of developing significant hypophosphatemia secondary to increased renal phosphate wasting through a mechanism involving FGF23. Monitoring plasma phosphate should be considered following FCM in patients with previous bariatric surgery. CLINICAL TRIAL REGISTRATION ISRCTN registry, ISRCTN12291677, https://www.isrctn.com.
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Affiliation(s)
- Manuela Schoeb
- Division of Endocrinology and Diabetes, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland.
| | - Andrea Räss
- Division of Endocrinology and Diabetes, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland
| | - Nicola Frei
- Division of General Internal Medicine, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Stefan Aczél
- Division of Endocrinology and Diabetes, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland
| | - Michael Brändle
- Division of Endocrinology and Diabetes, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland
- Division of General Internal Medicine, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Stefan Bilz
- Division of Endocrinology and Diabetes, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland
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16
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Raimann A, Mindler GT, Kocijan R, Bekes K, Zwerina J, Haeusler G, Ganger R. Multidisciplinary patient care in X-linked hypophosphatemic rickets: one challenge, many perspectives. Wien Med Wochenschr 2020; 170:116-123. [PMID: 31993875 PMCID: PMC7098922 DOI: 10.1007/s10354-019-00732-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/17/2019] [Indexed: 11/29/2022]
Abstract
X‑linked hypophosphatemic rickets (XLH, OMIM #307800) is a rare genetic metabolic disorder caused by dysregulation of fibroblast-like growth factor 23 (FGF23) leading to profound reduction in renal phosphate reabsorption. Impaired growth, severe rickets and complex skeletal deformities are direct consequences of hypophosphatemia representing major symptoms of XLH during childhood. In adults, secondary complications including early development of osteoarthritis substantially impair quality of life and cause significant clinical burden. With the global approval of the monoclonal FGF23 antibody burosumab, a targeted treatment with promising results in phase III studies is available for children with XLH. Nevertheless, complete phenotypic rescue is rarely achieved and remaining multisystemic symptoms demand multidisciplinary specialist care. Coordination of patient management within the major medical disciplines is a mainstay to optimize treatment and reduce disease burden. This review aims to depict different perspectives in XLH patient care in the setting of a multidisciplinary centre of expertise for rare bone diseases.
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Affiliation(s)
- Adalbert Raimann
- Comprehensive Center for Pediatrics, Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria. .,Vienna Bone and Growth Centre, Vienna, Austria.
| | - Gabriel T Mindler
- Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria.,Vienna Bone and Growth Centre, Vienna, Austria
| | - Roland Kocijan
- Hanusch Hospital of the WGKK and AUVA Trauma Center, 1st Medical Department at Hanusch Hospital, Ludwig Boltzmann Institute of Osteology, Vienna, Austria.,Vienna Bone and Growth Centre, Vienna, Austria
| | - Katrin Bekes
- Department of Pediatric Dentistry, School of Dentistry, Medical University of Vienna, Vienna, Austria
| | - Jochen Zwerina
- Hanusch Hospital of the WGKK and AUVA Trauma Center, 1st Medical Department at Hanusch Hospital, Ludwig Boltzmann Institute of Osteology, Vienna, Austria.,Vienna Bone and Growth Centre, Vienna, Austria
| | - Gabriele Haeusler
- Comprehensive Center for Pediatrics, Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria.,Vienna Bone and Growth Centre, Vienna, Austria
| | - Rudolf Ganger
- Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria.,Vienna Bone and Growth Centre, Vienna, Austria
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17
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Musgrove J, Wolf M. Editorial: awareness and prevention of intravenous iron-induced hypophosphataemia. Aliment Pharmacol Ther 2019; 50:609-610. [PMID: 31414533 DOI: 10.1111/apt.15437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- John Musgrove
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA.,Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
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18
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Detlie TE, Lindstrøm JC, Jahnsen ME, Finnes E, Zoller H, Moum B, Jahnsen J. Incidence of hypophosphatemia in patients with inflammatory bowel disease treated with ferric carboxymaltose or iron isomaltoside. Aliment Pharmacol Ther 2019; 50:397-406. [PMID: 31264261 DOI: 10.1111/apt.15386] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/30/2019] [Accepted: 06/01/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND Iron deficiency and iron deficiency anaemia are common complications in inflammatory bowel disease (IBD). In patients with moderate-to-severe anaemia, oral iron intolerance or ineffectiveness of oral iron, ferric carboxymaltose and iron isomaltoside are widely used. Hypophosphatemia is a side effect of both preparations. AIMS To investigate the occurrence of hypophosphatemia in IBD patients with iron deficiency/iron deficiency anaemia treated with high-dose intravenous iron. METHODS A prospective observational study of adult IBD patients with iron deficiency/iron deficiency anaemia was conducted at two study sites where patients received 1000 mg of ferric carboxymaltose or iron isomaltoside. At baseline, weeks 2 and 6, blood and faecal samples were collected. The primary endpoint was to determine the incidence of moderate-to-severe hypophosphatemia. Secondary endpoints included the total incidence of hypophosphatemia, possible risk factors for hypophosphatemia, and response to single-dose intravenous iron. RESULTS One hundred and thirty patients were included. In the per-protocol set, 52 patients received ferric carboxymaltose and 54 patients received iron isomaltoside. Ferric carboxymaltose treatment had a significantly higher incidence of moderate-to-severe hypophosphatemia compared with iron isomaltoside at week 2 (56.9% vs 5.7%, P < 0.001) and a higher incidence at week 6 (13.7% vs 1.9%, P = 0.054).The overall incidence of hypophosphatemia was significantly higher with ferric carboxymaltose compared with iron isomaltoside treatment at weeks 2 (72.5% vs 11.3%, P < 0.001) and 6 (21.6% vs 3.7%, P = 0.013). CONCLUSIONS In IBD patients with iron deficiency/iron deficiency anaemia, ferric carboxymaltose was associated with higher incidence, severity and persistence of hypophosphatemia compared with iron isomaltoside. The presence of moderate-to-severe hypophosphatemia beyond 6 weeks is a clinical concern that requires further investigation.
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Affiliation(s)
- Trond Espen Detlie
- Department of Gastroenterology, Akershus University Hospital, Lørenskog, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Jonas Christoffer Lindstrøm
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Health Services Research Unit, Akershus University Hospital, Lørenskog, Norway
| | - Marte Eide Jahnsen
- Department of Gastroenterology, Akershus University Hospital, Lørenskog, Norway
| | - Elisabeth Finnes
- Division of Medicine, Department of Gastroenterology, Oslo University Hospital Ullevål, Oslo, Norway
| | - Heinz Zoller
- Department of Medicine II, Gastroenterology and Hepatology, Medical University of Innsbruck, Innsbruck, Austria
| | - Bjørn Moum
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Division of Medicine, Department of Gastroenterology, Oslo University Hospital Ullevål, Oslo, Norway
| | - Jørgen Jahnsen
- Department of Gastroenterology, Akershus University Hospital, Lørenskog, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
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19
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Wheeler JA, Clinkenbeard EL. Regulation of Fibroblast Growth Factor 23 by Iron, EPO, and HIF. ACTA ACUST UNITED AC 2019; 5:8-17. [PMID: 31218207 DOI: 10.1007/s40610-019-0110-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose of review Fibroblast growth factor-23 (FGF23) is the key hormone produced in bone critical for phosphate homeostasis. Elevated serum phosphorus and 1,25dihydroxyvitaminD stimulates FGF23 production to promote renal phosphate excretion and decrease 1,25dihydroxyvitaminD synthesis. Thus completing the feedback loop and suppressing FGF23. Unexpectedly, studies of common and rare heritable disorders of phosphate handling identified links between iron and FGF23 demonstrating novel regulation outside the phosphate pathway. Recent Findings Iron deficiency combined with an FGF23 cleavage mutation was found to induce the autosomal dominant hypophosphatemic rickets phenotype. Physiological responses to iron deficiency, such as erythropoietin production as well as hypoxia inducible factor activation, have been indicated in regulating FGF23. Additionally, specific iron formulations, used to treat iron deficiency, alter post-translational processing thereby shifting FGF23 protein secretion. Summary Molecular and clinical studies revealed that iron deficiency, through several mechanisms, alters FGF23 at the transcriptional and post-translational level. This review will focus upon the novel discoveries elucidated between iron, its regulators, and their influence on FGF23 bioactivity.
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Affiliation(s)
- Jonathan A Wheeler
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Erica L Clinkenbeard
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
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20
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Wolf M, Chertow GM, Macdougall IC, Kaper R, Krop J, Strauss W. Randomized trial of intravenous iron-induced hypophosphatemia. JCI Insight 2018; 3:124486. [PMID: 30518682 DOI: 10.1172/jci.insight.124486] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/31/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Hypophosphatemia can complicate intravenous iron therapy, but no head-to-head trials compared the effects of newer intravenous iron formulations on risks and mediators of hypophosphatemia. METHODS In a randomized, double-blinded, controlled trial of adults with iron deficiency anemia from February 2016 to January 2017, we compared rates of hypophosphatemia in response to a single FDA-approved course of ferric carboxymaltose (n = 1,000) or ferumoxytol (n = 997). To investigate pathophysiological mediators of intravenous iron-induced hypophosphatemia, we nested within the parent trial a physiological substudy (ferric carboxymaltose, n = 98; ferumoxytol, n = 87) in which we measured fibroblast growth factor 23 (FGF23), calcitriol, and parathyroid hormone (PTH) at baseline and 1, 2, and 5 weeks later. RESULTS The incidence of hypophosphatemia was significantly higher in the ferric carboxymaltose versus the ferumoxytol group (<2.0 mg/dl, 50.8% vs. 0.9%; <1.3 mg/dl, 10.0% vs. 0.0%; P < 0.001), and hypophosphatemia persisted through the end of the 5-week study period in 29.1% of ferric carboxymaltose-treated patients versus none of the ferumoxytol-treated patients (P < 0.001). Ferric carboxymaltose, but not ferumoxytol, increased circulating concentrations of biologically active FGF23 (mean within-patient percentage change from baseline to week 2 peak: +302.8 ± 326.2% vs. +10.1 ± 61.0%; P < 0.001), which was significantly associated with contemporaneous hypophosphatemia, renal phosphate wasting, and decreased serum calcitriol and calcium, and increased PTH concentrations. CONCLUSIONS Ferric carboxymaltose rapidly increases biologically active FGF23 in patients with iron deficiency anemia. Paralleling hereditary and other acquired syndromes of hypophosphatemic rickets/osteomalacia, ferric carboxymaltose-induced FGF23 elevation triggers a pathophysiological cascade of renal phosphate wasting, calcitriol deficiency, and secondary hyperparathyroidism that frequently culminates in hypophosphatemia. TRIAL REGISTRATION ClinicalTrials.gov, NCT02694978FUNDING. AMAG Pharmaceuticals, Inc.Role of the funding source: This study was supported by AMAG Pharmaceuticals, Inc. The academic investigators designed the clinical trial, performed the analyses, and authored the manuscript with input from the coauthors from AMAG Pharmaceuticals, Inc.
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Affiliation(s)
- Myles Wolf
- Division of Nephrology, Department of Medicine, and.,Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Glenn M Chertow
- Division of Nephrology, Department of Medicine and.,Department of Health Research and Policy, Stanford University, Stanford, California, USA
| | | | - Robert Kaper
- AMAG Pharmaceuticals, Inc., Waltham, Massachusetts, USA
| | - Julie Krop
- AMAG Pharmaceuticals, Inc., Waltham, Massachusetts, USA
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21
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Tournis S, Michopoulos S, Makris K, Terpos E. Re: Hypophosphatemia, Severe Bone Pain, Gait Disturbance, and Fatigue Fractures After Iron Substitution in Inflammatory Bowel Disease: A Case Report. J Bone Miner Res 2018; 33:543-545. [PMID: 29281128 DOI: 10.1002/jbmr.3372] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 12/19/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Symeon Tournis
- Laboratory for Research of the Musculoskeletal System 'Th. Garofalidis', KAT Hospital, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece
| | | | | | - Evaggelos Terpos
- Department of Clinical Therapeutics, National and Kapodistrian University of Athens, School of Medicine, "Alexandra" General Hospital, Athens, Greece
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22
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Urbina T, Belkhir R, Rossi G, Carbonnel F, Pavy S, Collins M, Mariette X, Seror R. Iron Supplementation-Induced Phosphaturic Osteomalacia: FGF23 is the Culprit. J Bone Miner Res 2018; 33:540-542. [PMID: 29281120 DOI: 10.1002/jbmr.3369] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 12/19/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Tomas Urbina
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France.,Université Paris-Sud; INSERM U1184, Le Kremlin Bicêtre, France
| | - Rakiba Belkhir
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France.,Université Paris-Sud; INSERM U1184, Le Kremlin Bicêtre, France
| | - Geoffrey Rossi
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France.,Université Paris-Sud; INSERM U1184, Le Kremlin Bicêtre, France
| | - Franck Carbonnel
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France
| | - Stephan Pavy
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France.,Université Paris-Sud; INSERM U1184, Le Kremlin Bicêtre, France
| | - Michael Collins
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France
| | - Xavier Mariette
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France.,Université Paris-Sud; INSERM U1184, Le Kremlin Bicêtre, France
| | - Raphaèle Seror
- Assistance Publique-Hopitaux de Paris, Hôpitaux Universitaires Paris-Sud, Department of Rheumatology, Le Kremlin Bicêtre, France.,Université Paris-Sud; INSERM U1184, Le Kremlin Bicêtre, France
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