Heme iron polypeptide for the management of anaemia of chronic kidney disease

Oral iron therapy: Current concepts and future prospects for improving efficacy and outcomes

Iron deficiency (ID) and iron-deficiency anaemia (IDA) are global public health concerns, most commonly afflicting children, pregnant women and women of childbearing age. Pathological outcomes of ID include delayed cognitive development in children, adverse pregnancy outcomes and decreased work capacity in adults. IDA is usually treated by oral iron supplementation, typically using iron salts (e.g. FeSO4 ); however, dosing at several-fold above the RDA may be required due to less efficient absorption. Excess enteral iron causes adverse gastrointestinal side effects, thus reducing compliance, and negatively impacts the gut microbiome. Recent research has sought to identify new iron formulations with better absorption so that lower effective dosing can be utilized. This article outlines emerging research on oral iron supplementation and focuses on molecular mechanisms by which different supplemental forms of iron are transported across the intestinal epithelium and whether these transport pathways are subject to regulation by the iron-regulatory hormone hepcidin.

Innovations thérapeutiques dans la prise en charge de l’anémie de la maladie rénale chronique Therapeutic innovations in the management of chronic kidney disease-associated anemia

Anemia is a common complication of chronic kidney disease (CKD). The insufficient erythropoietin (EPO) production by the kidneys and iron deficiency are the main causes. Iron supplementation and the administration of recombinant EPO are the main treatment modalities. New iron formulations that can be administered orally, intravenously or directly via the dialysate have recently been developed to improve efficacy and tolerance. Ferric citrate administered orally can effectively corrects anemia in case of iron deficiency and in addition chelate phosphate in the gut lumen. Ferric carboxymaltose allows intravenous administration of larger doses given less frequently. Ferric pyrophosphate citrate administered directly via the dialysate allows the compensation of iron losses during the hemodialysis session. HIF-prolyl-hydroxylase inhibitors are a new therapeutic class of erythropoiesis-stimulating agents. Orally administered, they act by stabilizing the HIF transcription factor involved in the initiation of erythropoietin production by hypoxia. Several clinical studies have recently evaluated these new molecules in comparison with recombinant EPO. In CKD patients not yet on dialysis or undergoing dialysis therapy non-inferiority in correcting anemia has been demonstrated compared with recombinant EPO. The decrease in circulating hepcidin they induce appears greater than that induced by injectable recombinant EPO. Presently available reports on the safety of HIF-prolyl-hydroxylase inhibitors are reassuring but need to be confirmed in longer-term studies of larger size. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

Iron replacement therapy in the management of anaemia in non-dialysis Chronic kidney disease patients: Perspective of the Spanish Nephrology Society Anaemia Group

This work presents an update on the management of iron deficiency in patients with chronic kidney disease (CKD), either with or without anaemia. A review is made of the recommendations of the guidelines for the treatment of iron deficiency in CKD. It also presents new studies on iron deficiency in patients with CKD, as well as new findings about iron therapy and its impact on clinical outcomes. Anaemia is a common complication of CRF, and is associated with a decrease in the quality of life of the patients, as well as an increase in morbidity and mortality. Iron deficiency (absolute or functional) is common in non-dialysis chronic kidney disease patients, and may cause anaemia or a low response to erythropoiesis-stimulating agents. For this reason, the clinical guidelines for the treatment of the anaemia in Nephrology indicate the correction of the deficiency in the presence of anaemia. Iron replacement therapy is indicated in patients with CKD and anaemia (Hb < 12 g/dl) in accordance with the guidelines. There is no unanimity in the indication of iron replacement therapy in patients with Hb > 12 g/dl, regardless of whether they have an absolute or functional iron deficiency. Intravenous iron replacement therapy is safe, more efficient and rapid than oral therapy for achieving an increase haemoglobin lels and reducing the dose of erythropoiesis-stimulating agents. For the administration of intravenous iron in non-dialysis chronic renal failure patients a strategy of high doses and low frequency would be preferred on being more convenient for the patient, preserves better the venous capital, and is safe and cost-effective. Iron plays an essential role in energy metabolism and other body functions beyond the synthesis of haemoglobin, for which the iron deficiency, even in the absence of anaemia, could have harmful effects in patients with CKD. The correction of the iron deficiency, in the absence of anaemia is associated with functional improvement in patients with heart failure, and in muscle function or fatigue in patients without CKD. Despite the evidence of benefits in the correction of iron deficiency in patients with CKD, more studies are required to evaluate the impact of the correction of the iron deficiency in the absence of anaemia on morbidity and mortality, quality of life and physical capacity, as well as the long-term effect of oral and intravenous iron replacement therapy in this population.

Iron Therapy in Chronic Kidney Disease: Days of Future Past

Anemia affects millions of patients with chronic kidney disease (CKD) and prompt iron supplementation can lead to reductions in the required dose of erythropoiesis-stimulating agents, thereby reducing medical costs. Oral and intravenous (IV) traditional iron preparations are considered far from ideal, primarily due to gastrointestinal intolerability and the potential risk of infusion reactions, respectively. Fortunately, the emergence of novel iron replacement therapies has engendered a paradigm shift in the treatment of iron deficiency anemia in patients with CKD. For example, oral ferric citrate is an efficacious and safe phosphate binder that increases iron stores to maintain hemoglobin levels. Additional benefits include reductions in fibroblast growth factor 23 levels and the activation of 1,25 dihydroxyvitamin D. The new-generation IV iron preparations ferumoxytol, iron isomaltoside 1000, and ferric carboxymaltose are characterized by a reduced risk of infusion reactions and are clinically well tolerated as a rapid high-dose infusion. In patients undergoing hemodialysis (HD), ferric pyrophosphate citrate (FPC) administered through dialysate enables the replacement of ongoing uremic and HD-related iron loss. FPC transports iron directly to transferrin, bypassing the reticuloendothelial system and avoiding iron sequestration. Moreover, this paper summarizes recent advancements of hypoxia-inducible factor prolyl hydroxylase inhibitors and future perspectives in renal anemia management.

Comparison of Oral Iron Supplement Formulations for Normalization of Iron Status Following Roux-EN-y Gastric Bypass Surgery: a Randomized Trial

BACKGROUND

The evidence behind recommendations for treatment of iron deficiency (ID) following roux-en-y gastric bypass surgery (RYGB) lacks high quality studies.

SETTING

Academic, United States OBJECTIVE: The objective of the study is to compare the effectiveness of oral iron supplementation using non-heme versus heme iron for treatment of iron deficiency in RYGB patients.

METHODS

In a randomized, single-blind study, women post-RYGB and iron deficient received non-heme iron (FeSO₄, 195 mg/day) or heme iron (heme-iron-polypeptide, HIP, 31.5 to 94.5 mg/day) for 8 weeks. Measures of iron status, including blood concentrations of ferritin, soluble transferrin receptor (sTfR), and hemoglobin, were assessed.

RESULTS

At baseline, the mean ± standard deviation for age, BMI, and years since surgery of the sample was 41.5 ± 6.8 years, 34.4 ± 5.9 kg/m², and 6.9 ± 3.1 years, respectively; and there were no differences between FeSO₄ (N = 6) or HIP (N = 8) groups. Compliance was greater than 94%. The study was stopped early due to statistical and clinical differences between groups. Values before and after FeSO₄ supplementation, expressed as least square means (95% CI) were hemoglobin, 10.8 (9.8, 11.9) to 13.0 (11.9, 14.0) g/dL; sTfR, 2111 (1556, 2864) to 1270 (934, 1737) μg/L; ferritin, 4.9 (3.4, 7.2) to 15.5 (10.6, 22.6) μg/L; and sTfR:ferritin ratio, 542 (273, 1086) to 103 (51, 204); all p < 0.0001. With HIP supplementation, no change was observed in any of the iron status biomarkers (all p > 0.05).

CONCLUSIONS

In accordance with recommendations, oral supplementation using FeSO₄, but not HIP, was efficacious for treatment of iron deficiency after RYGB.

Protective Role of Histidine Supplementation Against Oxidative Stress Damage in the Management of Anemia of Chronic Kidney Disease

Anemia is a major health condition associated with chronic kidney disease (CKD). A key underlying cause of this disorder is iron deficiency. Although intravenous iron treatment can be beneficial in correcting CKD-associated anemia, surplus iron can be detrimental and cause complications. Excessive generation of reactive oxygen species (ROS), particularly by mitochondria, leads to tissue oxidation and damage to DNA, proteins, and lipids. Oxidative stress increase in CKD has been further implicated in the pathogenesis of vascular calcification. Iron supplementation leads to the availability of excess free iron that is toxic and generates ROS that is linked, in turn, to inflammation, endothelial dysfunction, and cardiovascular disease. Histidine is indispensable to uremic patients because of the tendency toward negative plasma histidine levels. Histidine-deficient diets predispose healthy subjects to anemia and accentuate anemia in chronic uremic patients. Histidine is essential in globin synthesis and erythropoiesis and has also been implicated in the enhancement of iron absorption from human diets. Studies have found that L-histidine exhibits antioxidant capabilities, such as scavenging free radicals and chelating divalent metal ions, hence the advocacy for its use in improving oxidative stress in CKD. The current review advances and discusses evidence for iron-induced toxicity in CKD and the mechanisms by which histidine exerts cytoprotective functions.

Iron therapy for managing anaemia in chronic kidney disease

PURPOSE OF REVIEW

Iron deficiency is a major contributory cause to the development of anaemia in chronic kidney disease (CKD), and thus, iron replacement therapy plays a critical role in the management of this condition. The two main routes for administering iron are oral and intravenous, and there have been a number of new publications relevant to both routes of administration.

RECENT FINDINGS

Recent developments on the topic of iron management in CKD include the introduction of new oral iron preparations, as well as two recent meta-analyses on iron therapy in CKD (one on oral versus intravenous iron, and one on high- versus low-dose intravenous iron in haemodialysis patients). There is also increasing interest in other strategies to improve iron availability, such as intradialytic iron, hypoxia-inducible factor stabilization and antihepcidin strategies.

SUMMARY

Even despite the latest publications in this field, we are still left with serious gaps in our evidence base on how best to provide supplemental iron to CKD patients. Most of the evidence suggests that intravenous iron is superior to oral iron in increasing haemoglobin and minimizing the use of erythropoiesis-stimulating agents, but the safety of intravenous iron remains a controversy. The PIVOTAL study will hopefully provide informative data to fill some of the gap in the evidence-base and inform best clinical practice.

Iron Therapy Challenges for the Treatment of Nondialysis CKD Patients

The clinical consequences of untreated, severe anemia in patients with nondialysis CKD can be significant, but disparities exist in the anemia treatment guidelines and position papers issued from working groups and associations across the world. These differ in hemoglobin target and iron levels and their emphasis on various iron markers and other clinical outcomes. Not surprisingly, disparities are observed in anemia treatment strategies among patients with nondialysis CKD across different areas of the world. Over the past decade, the prescription and dosage of both iron therapies and erythropoiesis-stimulating agents have shifted, with notable regional differences observed. Moreover, there is ongoing debate regarding oral versus intravenous administration of iron. Compared with oral iron therapy, which often leads to gastrointestinal adverse events, low patient adherence, and low efficacy, intravenous iron administration has been associated with potential serious adverse events, such as anaphylaxis. New iron-based compounds and drugs currently under development are reviewed to describe their potential benefits in the treatment of anemia in patients with CKD. New oral compounds, including iron-based phosphate binders, heme iron polypeptide, and liposomal iron, show different rates of absorption with possibly different efficacy and improved tolerability. These new potential therapies offer health care providers additional anemia treatment options for their patients with CKD; however, the management of anemia in the CKD population continues to present challenges that require prospective studies to identify the optimal iron therapy for patients.

Guidelines on the diagnosis and treatment of iron deficiency across indications: a systematic review

BACKGROUND

Guidelines on the diagnosis and treatment of iron deficiency (ID) vary widely across indications.

OBJECTIVE

We reviewed all available guidelines on the management of ID worldwide.

DESIGN

A literature search was conducted in PubMed, Cochrane, and EMBASE and in main professional association websites, limited to documents published between 1 January 2004 and 30 June 2014.

RESULTS

Of 127 guidelines identified, 29 were selected, involving 29 professional associations and issued from the United States (n = 8), Europe (n = 6), Britain (n = 4), Canada (n = 3), international organizations (n = 2), France (n = 2), Poland (n = 1), Australia (n = 1), Mexico (n = 1), and Japan (n = 1). A total of 22 and 27 guidelines provided recommendations on diagnosis and treatment of ID, respectively. To define ID, all guidelines recommended a concentration for serum ferritin. One-half of them (10 of 22) proposed transferrin saturation (TSAT) as an alternative or complementary diagnostic test. To treat ID, most of the guidelines (18 of 27) recommended preferentially the oral route if possible, particularly in children and in women in the pre- or postpregnancy period. Iron supplementation should be administered intravenously according to 13 of 27 guidelines, particularly in patients with chronic kidney disease (CKD) (n = 7) and chemotherapy-induced anemia (n = 5). Treatment targets for ID included an increase in hemoglobin concentrations to 10-12 g/dL or normalization (n = 8) and serum ferritin >100 μg/L (n = 7) or 200 μg/L (n = 4). For the latter, in some situations, such as CKD, ferritin concentrations should not exceed 500 μg/L (n = 5) or 800 μg/L (n = 5). Only 9 guidelines recommended TSAT as a target, proposing various thresholds ranging from 20% to 50%.

CONCLUSIONS

It appears that for the diagnosis of ID, a cutoff of 100 μg/L for serum ferritin concentration should be considered in most conditions and 20% for TSAT, except in particular situations, including young healthy women with heavy menstrual flow. New indications of intravenous iron supplementation are emerging.