Non-transferrin-bound iron in plasma following administration of oral iron drugs

Impaired pancreatic beta-cell function after a single dose of oral iron: a before-and-after (pre-post) study

INTRODUCTION

Although in vitro and animal studies have shown that iron loading in pancreatic beta-cells impaired insulin secretion, no human studies have documented the acute effects of oral iron on beta-cell insulin secretory capacity. In this study, we determined beta-cell insulin secretory capacity at baseline and after a single oral dose of iron (ferrous sulphate, 120 mg elemental iron) in healthy male individuals.

METHODS

Fifteen healthy male volunteers underwent an oral glucose tolerance test (OGTT) to document baseline glucose tolerance and insulin secretion kinetics (baseline OGTT). One week later, the same subjects underwent a second OGTT, two hours after an oral dose of ferrous sulfate (120 mg of elemental iron) (post-iron OGTT). Changes in disposition index, insulin secretion kinetics, glucose tolerance, insulin resistance, insulin clearance, and iron-related parameters in serum were determined.

RESULTS

Compared to baseline OGTT, the areas under the curve (AUC) for serum iron and transferrin saturation increased by 125% and 118% respectively, in the post-iron OGTT. The disposition index decreased by 20% (p=0.009) and the AUC for glucose concentrations increased by 5.7% (p<0.001) during the post-iron OGTT. The insulin secretion rate was marginally lower during the first hour (-3.5%, p=0.63), but became significantly higher during the second hour (22%, p=0.005) of the post-iron OGTT. Insulin resistance and insulin clearance rate were not affected by iron intake.

CONCLUSION

The decrease in disposition index and glucose tolerance observed after the oral dose of iron points to an acute iron-induced impairment in pancreatic beta-cell insulin secretory capacity. This article is protected by copyright. All rights reserved.

The (Bio)Chemistry of Non-Transferrin-Bound Iron

In healthy individuals, virtually all blood plasma iron is bound by transferrin. However, in several diseases and clinical conditions, hazardous non-transferrin-bound iron (NTBI) species occur. NTBI represents a potentially toxic iron form, being a direct cause of oxidative stress in the circulating compartment and tissue iron loading. The accumulation of these species can cause cellular damage in several organs, namely, the liver, spleen, and heart. Despite its pathophysiological relevance, the chemical nature of NTBI remains elusive. This has precluded its use as a clinical biochemical marker and the development of targeted therapies. Herein, we make a critical assessment of the current knowledge of NTBI speciation. The currently accepted hypotheses suggest that NTBI is mostly iron bound to citric acid and iron bound to serum albumin, but the chemistry of this system remains fuzzy. We explore the complex chemistry of iron complexation by citric acid and its implications towards NTBI reactivity. Further, the ability of albumin to bind iron is revised and the role of protein post-translational modifications on iron binding is discussed. The characterization of the NTBI species structure may be the starting point for the development of a standardized analytical assay, the better understanding of these species’ reactivity or the identification of NTBI uptake mechanisms by different cell types, and finally, to the development of new therapies.

Role of redox iron towards an increase in mortality among patients: a systemic review and meta-analysis

An increase in biochemical concentrations of non-transferrin bound iron (NTBI) within the patients with an increase in serum iron concentration was evaluated with the following objectives: (a) Iron overloading diseases/conditions with free radicle form of ‘iron containing’ reactive oxygen species (ROS) and its imbalance mediated mortality, and (b) Intervention with iron containing drugs in context to increased redox iron concentration and treatment induced mortality. Literature search was done within Pubmed and cochrane review articles. The Redox iron levels are increased during dys-erythropoiesis and among transfusion recipient population and are responsive to iron-chelation therapy. Near expiry ‘stored blood units’ show a significant rise in the ROS level. Iron mediated ROS damage may be estimated by the serum antioxidant level, and show reduction in toxicity with high antioxidant, low pro-oxidant levels. Iron drug therapy causes a significant increase in NTBI and labile iron levels. Hospitalized patients on iron therapy however show a lower mortality rate. Serum ferritin is a mortality indicator among the high-dose iron therapy and transfusion dependent population. The cumulative difference of pre-chelation to post chelation ROS iron level was 0.97 (0.62; 1.32; N=261) among the transfusion dependent subjects and 2.89 (1.81–3.98; N=130) in the post iron therapy ‘iron ROS’ group. In conclusion, iron mediated mortality may not be mediated by redox iron among multi-transfused and iron overloaded patients.

Mechanism of Action and Clinical Attributes of Auryxia® (Ferric Citrate)

Chronic kidney disease (CKD) is a major cause of morbidity and premature mortality and represents a significant global public health issue. Underlying this burden are the many complications of CKD, including mineral and bone disorders, anemia, and accelerated cardiovascular disease. Hyperphosphatemia and elevated levels of fibroblast growth factor 23 (FGF23) have been identified as key independent risk factors for the adverse cardiovascular outcomes that frequently occur in patients with CKD. Auryxia® (ferric citrate; Keryx Biopharmaceuticals, Inc., Boston, MA, USA) is an iron-based compound with distinctive chemical characteristics and a mechanism of action that render it dually effective as a therapy in patients with CKD; it has been approved as a phosphate binder for the control of serum phosphate levels in adult CKD patients treated with dialysis and as an iron replacement product for the treatment of iron deficiency anemia in adult CKD patients not treated with dialysis. This review focuses on Auryxia, its mechanism of action, and the clinical attributes that differentiate it from other, non-pharmaceutical-grade, commercially available forms of ferric citrate and from other commonly used phosphate binder and iron supplement therapies for patients with CKD. Consistent with the chemistry and mechanism of action of Auryxia, multiple clinical studies have demonstrated its efficacy in both lowering serum phosphate levels and improving iron parameters in patients with CKD. Levels of FGF23 decrease significantly with Auryxia treatment, but the effects associated with the cardiovascular system remain to be evaluated in longer-term studies.

Iron and Vitamin D/Calcium Deficiency after Gastric Bypass: Mechanisms Involved and Strategies to Improve Oral Supplement Disposition

Background:

Nutritional deficiencies are common following Roux-en-Y Gastric Bypass (RYGB). Aetiology is diverse; including non-compliance, altered diet, unresolved preoperative deficiency and differential degrees of post-operative malabsorption occurring as function of length of bypassed intestine. Iron and calcium/vitamin D deficiency occur in up to 50% of patients following RYGB. Currently, treatment strategies recommend the prescription of oral supplements for those who become deficient. Meanwhile, debate exists regarding the absorption capacity of these post-operatively and their efficacy in treating deficiency.

Objective:

To examine the disposition of oral iron and calcium/vitamin D supplementation following RYGB. Methods: A literature review was carried out using PubMed and Embase. Data from the key interventional studies investigating iron and calcium/vitamin D oral supplement absorption and efficacy following RYGB was summarized.

Results:

Absorption of both iron and vitamin D/calcium is adversely affected following RYGB. Distribution and metabolism may be altered by the predominance of paracellular absorption pathways which promote unregulated influx into the circulatory system. Overall, studies indicate that current supplementation strategies are efficacious to a degree in treating deficiency following RYGB, generally restoration of optimal status is not achieved.

Conclusion:

Oral supplement disposition is altered following RYGB. As a result, patients are required to take regimens of oral supplementation indefinitely. The dosage which confers optimum health benefit while avoiding potential toxicity and tolerability issues remains unknown. Novel preparations with improved disposition could help limit the extent of post-RYGB nutritional deficiencies.

Safety and efficacy of sucrosomial iron in inflammatory bowel disease patients with iron deficiency anemia

Iron deficiency anemia (IDA) is one of the most common complications of inflammatory bowel disease (IBD). We planned a prospective study to address tolerability and efficacy of sucrosomial iron, a new oral formulation of ferric pyrophosphate, in IBD patients. Thirty patients with a confirmed diagnosis of Crohn's Disease (CD) or ulcerative colitis (UC) and mild IDA were enrolled. Patients with severe IBD were excluded. All patients underwent 12 weeks of oral treatment with 30 mg/day of sucrosomial iron. Treatment compliance and adverse events were investigated every 4 weeks. Iron status, hematological parameters and IBD activity scores were determined at baseline and at the end of treatment, as well as serum hepcidin and non-transferrin bound iron (NTBI) levels. Twenty-four (80%) patients took more than 90% of the prescribed regimen. Forty-four adverse events (AEs) were recorded, but none of them is considered certainly or probably related to the study treatment. Interestingly, only eleven gastrointestinal events were recorded in 9 (30%) patients. At the end of treatment, all iron parameters improved significantly and Hb increased in 86% of patients (from 11.67 to 12.37 g/dl, p = 0.001). Serum hepcidin showed a significant increase in 79% of patients and became positively correlated with C-reactive protein (CRP) at the end of the study, while NTBI remained below the detection threshold after iron supplementation. The IBD activity scores improved in both CD and UC. This pilot interventional study supports the therapeutic use of sucrosomial iron in IBD and paves the way for future studies in larger or more difficult IBD populations.

An investigation of the effects of curcumin on iron overload, hepcidin level, and liver function in β-thalassemia major patients: A double-blind randomized controlled clinical trial

This study investigated the effects of curcumin, the active polyphenol in turmeric, on iron overload, hepcidin level, and liver function in β-thalassemia major patients. This double-blind randomized controlled clinical trial was conducted on 68 β-thalassemia major patients. The subjects were randomly divided into 2 groups to receive either 500 mg curcumin capsules (total: 1,000 mg) twice daily or placebo for 12 weeks. Dietary intakes and biochemical variables including hemoglobin, transferrin saturation, total iron binding capacity, nontransferrin bound iron (NTBI), ferritin, hepcidin, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were assessed at the beginning and end of the trial. Curcumin significantly reduced serum levels of NTBI (2.83 ± 1.08 compared with 2.22 ± 0.97 μmol/L, p = .001), ALT (42.86 ± 11.15 compared with 40.60 ± 9.89 U/L, p = .018), and AST (49.45 ± 12.39 compared with 46.30 ± 10.85 U/L, p = .002) at the end of the study. Based on analysis of covariance, a significant decrease was also observed in levels of NTBI (2.22 ± 0.97 vs. 2.55 ± 0.94 μmol/L, p = .026), ALT (40.60 ± 9.89 vs. 45.01 ± 10.42 U/L, p = .004), and AST (46.30 ± 10.85 vs. 50.99 ± 9.36 U/L, p = .009) in curcumin group in comparison with placebo group. There were no significant changes in hepcidin and other variables in any of the 2 groups. Curcumin administration alleviated iron burden and liver dysfunction by reducing NTBI, ALT, and AST levels in patients with β-thalassemia major.

Transport of Non-Transferrin Bound Iron to the Brain: Implications for Alzheimer's Disease

A direct correlation between brain iron and Alzheimer's disease (AD) raises questions regarding the transport of non-transferrin-bound iron (NTBI), a toxic but less researched pool of circulating iron that is likely to increase due to pathological and/or iatrogenic systemic iron overload. Here, we compared the distribution of radiolabeled-NTBI (59Fe-NTBI) and transferrin-bound iron (59Fe-Tf) in mouse models of iron overload in the absence or presence of inflammation. Following a short pulse, most of the 59Fe-NTBI was taken up by the liver, followed by the kidney, pancreas, and heart. Notably, a strong signal of 59Fe-NTBI was detected in the brain ventricular system after 2 h, and the brain parenchyma after 24 h. 59Fe-Tf accumulated mainly in the femur and spleen, and was transported to the brain at a much slower rate than 59Fe-NTBI. In the kidney, 59Fe-NTBI was detected in the cortex after 2 h, and outer medulla after 24 hours. Most of the 59Fe-NTBI and 59Fe-Tf from the kidney was reabsorbed; negligible amount was excreted in the urine. Acute inflammation increased the uptake of 59Fe-NTBI by the kidney and brain from 2-24 hours. Chronic inflammation, on the other hand, resulted in sequestration of iron in the liver and kidney, reducing its transport to the brain. These observations provide direct evidence for the transport of NTBI to the brain, and reveal a complex interplay between inflammation and brain iron homeostasis. Further studies are necessary to determine whether transient increase in NTBI due to systemic iron overload is a risk factor for AD.

Iron Absorption from Iron-Enriched Aspergillus oryzae Is Similar to Ferrous Sulfate in Healthy Female Subjects

BACKGROUND

Iron deficiency anemia (IDA) remains a global health issue, affecting mainly children and adolescent and pregnant women. Because of problems associated with current iron compounds used in both supplementation and fortification areas, there is an emerging interest in new natural iron sources to combat IDA.

OBJECTIVE

The objective of this study was to compare the iron absorption of iron-enriched Aspergillus oryzae [Aspiron (ASP)] with FeSO4 in humans.

METHODS

Iron absorption was assessed using stable isotope and serum iron response methods after oral intake of iron by healthy women in 2 separate studies. In the first study, ASP was intrinsically labelled with 58Fe into a dry form containing 8% iron. Subjects (n = 16, 18-35 y) were randomly assigned to consume liquid semipurified meals labelled with 2 stable iron isotopes, 57FeSO4 (10 mg) and ASP containing 2 mg 58Fe and 8 mg natural abundance iron, in 2 visits. Isotope enrichment was measured 2 wk after the last meal was eaten. In the second study, 17 subjects were randomly assigned to consume a test meal with 3 iron supplements during 3 separate visits: FeSO4, 10 mg Fe, and ASP in 2 iron doses, 10 mg and 20 mg. Changes in serum iron were measured at regular intervals for 4 h after supplementation.

RESULTS

The first study showed that the difference in iron absorption from FeSO4 and ASP was not significant (17.18% ± 14.2% compared to 15.14% ± 12.3%; P = 0.07). The results of the second study suggested that the iron from ASP was released slowly compared to FeSO4 and the area under the curve did not reflect the absorption of ASP iron, but rather the rate of iron release.

CONCLUSIONS

Iron-enriched A. oryzae has high relative bioavailability and may cause lower iron surges into the blood compared to FeSO4.

Management of inflammatory bowel disease-related anemia and iron deficiency with specific reference to the role of intravenous iron in current practice

INTRODUCTION

Anemia is a common extraintestinal manifestation in patients with inflammatory bowel disease, impacting disease prognosis, morbidity, hospitalization rates and time lost from work. While iron deficiency anemia and anemia of chronic inflammation predominate, combinations of hematimetric and biochemical markers facilitate the diagnosis and targeted therapy of other etiologies according to their underlying pathophysiological causes. Intravenous iron replacement is currently recommended in IBD patients with moderate to severe anemia or intolerance to oral iron. Areas covered: This review examines the impact, pathophysiology and diagnostics of iron deficiency and anemia, compares the characteristics and safety profiles of available oral and intravenous iron preparations, and highlights issues which require consideration in decision making for therapy administration and monitoring. Expert opinion: Modern intravenous iron formulations have been shown to be safe and effective in IBD patients, allowing rapid anemia correction and repletion of iron stores. While traditional oral iron preparations are associated with increased inflammation, negative effects on the microbiome, and poor tolerance and compliance, first clinical trial data indicate that newer oral compounds such as ferric maltol and sucrosomial iron offer improved tolerability and may thus offer a viable alternative for the future.

Molecular and Cellular Bases of Iron Metabolism in Humans

Iron is a microelement with the most completely studied biological functions. Its wide dissemination in nature and involvement in key metabolic pathways determine the great importance of this metal for uni- and multicellular organisms. The biological role of iron is characterized by its indispensability in cell respiration and various biochemical processes providing normal functioning of cells and organs of the human body. Iron also plays an important role in the generation of free radicals, which under different conditions can be useful or damaging to biomolecules and cells. In the literature, there are many reviews devoted to iron metabolism and its regulation in pro- and eukaryotes. Significant progress has been achieved recently in understanding molecular bases of iron metabolism. The purpose of this review is to systematize available data on mechanisms of iron assimilation, distribution, and elimination from the human body, as well as on its biological importance and on the major iron-containing proteins. The review summarizes recent ideas about iron metabolism. Special attention is paid to mechanisms of iron absorption in the small intestine and to interrelationships of cellular and extracellular pools of this metal in the human body.

Can Iron Treatments Aggravate Epistaxis in Some Patients With Hereditary Hemorrhagic Telangiectasia?

OBJECTIVES/HYPOTHESIS

To examine whether there is a rationale for iron treatments precipitating nosebleeds (epistaxis) in a subgroup of patients with hereditary hemorrhagic telangiectasia (HHT).

STUDY DESIGN

Survey evaluation of HHT patients, and a randomized control trial in healthy volunteers.

METHODS

Nosebleed severity in response to iron treatments and standard investigations were evaluated by unbiased surveys in patients with HHT. Serial blood samples from a randomized controlled trial of 18 healthy volunteers were used to examine responses to a single iron tablet (ferrous sulfate, 200 mg).

RESULTS

Iron tablet users were more likely to have daily nosebleeds than non-iron-users as adults, but there was no difference in the proportions reporting childhood or trauma-induced nosebleeds. Although iron and blood transfusions were commonly reported to improve nosebleeds, 35 of 732 (4.8%) iron tablet users, in addition to 17 of 261 (6.5%) iron infusion users, reported that their nosebleeds were exacerbated by the respective treatments. These rates were significantly higher than those reported for control investigations. Serum iron rose sharply in four of the volunteers ingesting ferrous sulfate (by 19.3-33.1 μmol/L in 2 hours), but not in 12 dietary controls (2-hour iron increment ranged from -2.2 to +5.0 μmol/L). High iron absorbers demonstrated greater increments in serum ferritin at 48 hours, but transient rises in circulating endothelial cells, an accepted marker of endothelial damage.

CONCLUSIONS

Iron supplementation is essential to treat or prevent iron deficiency, particularly in patients with pathological hemorrhagic iron losses. However, in a small subgroup of individuals, rapid changes in serum iron may provoke endothelial changes and hemorrhage.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:2468-2474, 2016.

ТЕХНОЛОГІЯ ОТРИМАННЯ ЗАЛІЗОВМІСНОГО КОМПЛЕКСУ НА ОСНОВІ ПОЛІСАХАРИДІВ ПЕЧЕРИЦІ ДВОСПОРОВОЇ

Розроблено технологію отримання залізовмісного комплексу на основі полісахаридів печериці дво-спорової, яка складається з двох стадій: вилучення полісахаридів та формування залізовмісного комплексу. Встанов-лено, що одержувати полісахариди з сировини доцільно екстракцією 3 % розчином натрій гідроксиду протягом 4 год зподальшою очисткою від речовин невуглеводної природи. У складі полісахаридів домінує галактоглюкан. Раціональ-ними умовами отримання залізовмісного комплексу на основі полісахаридів грибів є суміщення розчинів ферум (III)хлориду та полісахаридів; концентрації реагуючих речовин становлять: Fe3+ – 0,075 %, полісахаридів – 0,113 %, масо-ве співвідношення залізо : полісахариди 1,0 : 1,5, рН середовища – 11,5. Комплекс стійкий до дії агресивних середо-вищ травного тракту, є мікробіологічно безпечним та залишається доброякісним протягом 12 місяців зберігання. Він єефективним протианемічним засобом.

Low Dose Iron Treatments Induce a DNA Damage Response in Human Endothelial Cells within Minutes

BACKGROUND

Spontaneous reports from patients able to report vascular sequelae in real time, and recognition that serum non transferrin bound iron may reach or exceed 10μmol/L in the blood stream after iron tablets or infusions, led us to hypothesize that conventional iron treatments may provoke acute vascular injury. This prompted us to examine whether a phenotype could be observed in normal human endothelial cells treated with low dose iron.

METHODOLOGY

Confluent primary human endothelial cells (EC) were treated with filter-sterilized iron (II) citrate or fresh media for RNA sequencing and validation studies. RNA transcript profiles were evaluated using directional RNA sequencing with no pre-specification of target sequences. Alignments were counted for exons and junctions of the gene strand only, blinded to treatment types.

PRINCIPAL FINDINGS

Rapid changes in RNA transcript profiles were observed in endothelial cells treated with 10μmol/L iron (II) citrate, compared to media-treated cells. Clustering for Gene Ontology (GO) performed on all differentially expressed genes revealed significant differences in biological process terms between iron and media-treated EC, whereas 10 sets of an equivalent number of randomly selected genes from the respective EC gene datasets showed no significant differences in any GO terms. After 1 hour, differentially expressed genes clustered to vesicle mediated transport, protein catabolism, and cell cycle (Benjamini p = 0.0016, 0.0024 and 0.0032 respectively), and by 6 hours, to cellular response to DNA damage stimulus most significantly through DNA repair genes FANCG, BLM, and H2AFX. Comet assays demonstrated that 10μM iron treatment elicited DNA damage within 1 hour. This was accompanied by a brisk DNA damage response pulse, as ascertained by the development of DNA damage response (DDR) foci, and p53 stabilization.

SIGNIFICANCE

These data suggest that low dose iron treatments are sufficient to modify the vascular endothelium, and induce a DNA damage response.

Ferrous sulfate, but not iron polymaltose complex, aggravates local and systemic inflammation and oxidative stress in dextran sodium sulfate-induced colitis in rats

Background and aims

Iron deficiency is common in inflammatory bowel disease, yet oral iron therapy may worsen the disease symptoms and increase systemic and local oxidative stress. The aim of this study was to compare the effects of oral ferrous sulfate and iron polymaltose complex on inflammatory and oxidative stress markers in colitic rats.

Methods

Animals were divided into four groups with ten animals each. Rats of three groups received dextran sodium sulfate to induce colitis and animals of two of these groups received 5 mg iron/kg of body weight a day, as ferrous sulfate or iron polymaltose complex, for 7 days. Gross colon anatomy, histology of colon and liver, stainings of L-ferritin, Prussian blue, hepcidin, tumor necrosis factor-α, and interleukin-6, as well serum levels of liver enzymes, inflammatory markers, and iron markers, were assessed.

Results

Body weight, gross anatomy, crypt injury and inflammation scores, inflammatory parameters in liver and colon, as well as serum and liver hepcidin levels were not significantly different between colitic animals without iron treatment and colitic animals treated with iron polymaltose complex. In contrast, ferrous sulfate treatment caused significant worsening of these parameters. As opposed to ferrous sulfate, iron polymaltose complex caused less or no additional oxidative stress in the colon and liver compared to colitic animals without iron treatment.

Conclusion

Iron polymaltose complex had negligible effects on colonic tissue erosion, local or systemic oxidative stress, and local or systemic inflammation, even at high therapeutic doses, and may thus represent a valuable oral treatment of iron deficiency in inflammatory bowel disease.

Assessment of morphological and functional changes in organs of rats after intramuscular introduction of iron nanoparticles and their agglomerates

The research was performed on male Wistar rats based on assumptions that new microelement preparations containing metal nanoparticles and their agglomerates had potential. Morphological and functional changes in tissues in the injection site and dynamics of chemical element metabolism (25 indicators) in body were assessed after repeated intramuscular injections (total, 7) with preparation containing agglomerate of iron nanoparticles. As a result, iron depot was formed in myosymplasts of injection sites. The quantity of muscle fibers having positive Perls' stain increased with increasing number of injections. However, the concentration of the most chemical elements and iron significantly decreased in the whole skeletal muscle system (injection sites are not included). Consequently, it increased up to the control level after the sixth and the seventh injections. Among the studied organs (liver, kidneys, and spleen), Caspase-3 expression was revealed only in spleen. The expression had a direct dependence on the number of injections. Processes of iron elimination from preparation containing nanoparticles and their agglomerates had different intensity.

Iron metabolism in hemodialyzed patients - a story half told?

INTRODUCTION

All living organisms have evolved sophisticated mechanisms to maintain appropriate iron levels in their cells and within their body. Recently our understanding of iron metabolism has dramatically increased. Overt labile plasma iron (LPI) represents a component of non-transferrin bound iron (NTBI) that is both redox active and chelatable, capable of permeating into organs and inducing tissue iron overload. The LPI measures the iron-specific capacity of a given sample to produce reactive oxygen species. We studied for the first time NTBI correlations with markers of iron status and inflammation in prevalent hemodialyzed patients.

MATERIAL AND METHODS

Complete blood count, urea, serum lipids, fasting glucose, creatinine, ferritin, serum iron, total iron binding capacity (TIBC) were studied by standard laboratory method. The NTBI was assessed commercially available kits from Aferrix Ltd in Tel Aviv, Israel. A test result of 0.6 units of LPI or more indicates a potential for iron-mediated production of reactive oxygen species in the sample.

RESULTS

Patients with LPI units ≥ 0.6 had higher serum iron, erythropoiesis stimulating agents (ESA) dose, ferritin, high-sensitivity C-reactive protein (hsCRP), hepcidin and lower hemojuvelin. In hemodialyzed patients NTBI correlated with hsCRP (r = 0.37, p < 0.01), ferritin (r = 0.41, p < 0.001), IL-6 (r = 0.43, p < 0.001). In multivariate analysis predictors of NTBI were hemoglobin and alkaline phosphatase, explaining 58% of the variability.

CONCLUSIONS

Elevated NTBI in HD may be due to disturbed iron metabolism. Anemia and liver function might also contribute to the presence of NTBI in this population.

A novel method for non-transferrin-bound iron quantification by chelatable fluorescent beads based on flow cytometry

The reliable measurement of non-transferrin-bound iron (NTBI) in serum has proved to be difficult and generally time consuming. We have sought a simple and fast method for such a determination. We adopted a fluorescence assay and designed a fluorescent dye with a chelating agent attached to sense iron. To avoid autofluorescence from serum samples, the iron probes were linked to beads and the autofluorescence could be separated and excluded from the measurement by flow cytometry due to the size difference between beads and serum proteins. Fluorescent beads containing both fluorescent and chelating moieties have been synthesized. The nature of the chelating function has been systematically investigated using four different chelators: bidentate hydroxypyranone, bidentate hydroxypyridinone, hexadentate hydroxypyranone and hexadentate hydroxypyridinone, each with different iron affinity constants. Competition studies demonstrate that the hexadentate hydroxypyridinone-based beads are capable of scavenging most of low molecular mass and albumin-bound iron but negligible amounts of iron from transferrin and ferritin. Serum samples from 30 patients with different types of disease and normal volunteers were measured. The concentrations of NTBI fall in the range -0.41 to +6.5 μM. The data have been compared with those obtained from the traditional 'NTA' method.

Nanoparticulate iron(III) oxo-hydroxide delivers safe iron that is well absorbed and utilised in humans

Iron deficiency is the most common nutritional disorder worldwide with substantial impact on health and economy. Current treatments predominantly rely on soluble iron which adversely affects the gastrointestinal tract. We have developed organic acid-modified Fe(III) oxo-hydroxide nanomaterials, here termed nano Fe(III), as alternative safe iron delivery agents. Nano Fe(III) absorption in humans correlated with serum iron increase (P < 0.0001) and direct in vitro cellular uptake (P = 0.001), but not with gastric solubility. The most promising preparation (iron hydroxide adipate tartrate: IHAT) showed ~80% relative bioavailability to Fe(II) sulfate in humans and, in a rodent model, IHAT was equivalent to Fe(II) sulfate at repleting haemoglobin. Furthermore, IHAT did not accumulate in the intestinal mucosa and, unlike Fe(II) sulfate, promoted a beneficial microbiota. In cellular models, IHAT was 14-fold less toxic than Fe(II) sulfate/ascorbate. Nano Fe(III) manifests minimal acute intestinal toxicity in cellular and murine models and shows efficacy at treating iron deficiency anaemia.

FROM THE CLINICAL EDITOR

This paper reports the development of novel nano-Fe(III) formulations, with the goal of achieving a magnitude less intestinal toxicity and excellent bioavailability in the treatment of iron deficiency anemia. Out of the tested preparations, iron hydroxide adipate tartrate met the above criteria, and may become an important tool in addressing this common condition.

Circulating non-transferrin-bound iron after oral administration of supplemental and fortification doses of iron to healthy women: a randomized study

BACKGROUND

After the oral administration of iron, the production of circulating non-transferrin-bound iron may contribute to an increased risk of illness in malaria-endemic areas that lack effective medical services.

OBJECTIVE

In healthy women with a range of body iron stores, we aimed to determine effects on the production of circulating non-transferrin-bound iron resulting from the oral administration of 1) a supplemental dose of iron (60 mg) with water, 2) a supplemental dose of iron (60 mg) with a standard test meal, and 3) a fortification dose of iron (6 mg) with a standard test meal.

DESIGN

With the use of serum ferritin as the indicator, healthy women with replete iron stores (ferritin concentration >25 μg/L; n = 16) and reduced iron stores (ferritin concentration ≤25 μg/L; n = 16) were enrolled in a prospective, randomized, crossover study. After the oral administration of aqueous solutions of ferrous sulfate isotopically labeled with ⁵⁴Fe, ⁵⁷Fe, or ⁵⁸Fe, blood samples were collected for 8 h, and iron absorption was estimated by erythrocyte incorporation at 14 d.

RESULTS

At 4 h, serum non-transferrin-bound iron reached peaks with geometric mean (95% CI) concentrations of 0.81 μmol/L (0.56, 1.1 μmol/L) for 60 mg Fe with water and 0.26 μmol/L (0.15, 0.38 μmol/L) for 60 mg Fe with food but was at assay limits of detection (0.1 μmol Fe/L) for 6 mg Fe with food. For the 60 mg Fe without food, the area under the curve over 8 h for serum non-transferrin-bound iron was positively correlated with the amount of iron absorbed (R = 0.49, P < 0.01) and negatively correlated with serum ferritin (R = -0.39, P < 0.05).

CONCLUSIONS

In healthy women, the production of circulating non-transferrin-bound iron is determined by the rate and amount of iron absorbed. The highest concentrations of non-transferrin-bound iron resulted from the administration of supplemental doses of iron without food. Little or no circulating non-transferrin-bound iron resulted from the consumption of a meal with a fortification dose of iron.

Ferroportin mediates the intestinal absorption of iron from a nanoparticulate ferritin core mimetic in mice

The ferritin core is composed of fine nanoparticulate Fe(3+) oxohydroxide, and we have developed a synthetic mimetic, nanoparticulate Fe(3+) polyoxohydroxide (nanoFe(3+)). The aim of this study was to determine how dietary iron derived in this fashion is absorbed in the duodenum. Following a 4 wk run-in on an Fe-deficient diet, mice with intestinal-specific disruption of the Fpn-1 gene (Fpn-KO), or littermate wild-type (WT) controls, were supplemented with Fe(2+) sulfate (FeSO4), nanoFe(3+), or no added Fe for a further 4 wk. A control group was Fe sufficient throughout. Direct intestinal absorption of nanoFe(3+) was investigated using isolated duodenal loops. Our data show that FeSO4 and nanoFe(3+) are equally bioavailable in WT mice, and at wk 8 the mean ± SEM hemoglobin increase was 18 ± 7 g/L in the FeSO4 group and 30 ± 5 g/L in the nanoFe(3+) group. Oral iron failed to be utilized by Fpn-KO mice and was retained in enterocytes, irrespective of the iron source. In summary, although nanoFe(3+) is taken up directly by the duodenum its homeostasis is under the normal regulatory control of dietary iron absorption, namely via ferroportin-dependent efflux from enterocytes, and thus offers potential as a novel oral iron supplement.

The complex interplay of iron metabolism, reactive oxygen species, and reactive nitrogen species: insights into the potential of various iron therapies to induce oxidative and nitrosative stress

Production of minute concentrations of superoxide (O2(*-)) and nitrogen monoxide (nitric oxide, NO*) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance-a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O2(*-), hydrogen peroxide (H2O2), and NO*. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O2(*-), H2O2, NO*, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us develop better tolerated and more efficient therapies for various dysfunctions of iron metabolism.

Differences in Circulating Non-Transferrin-Bound Iron after Oral Administration of Ferrous Sulfate, Sodium Iron EDTA, or Iron Polymaltose in Women with Marginal Iron Stores

Background

The adverse interactions between iron supplements and malaria have driven the assessment of new therapeutic options for anemia prophylaxis in areas holoendemic for falciparum malaria.

Objective

To determine the responses of circulating non-transferrin-bound iron (NTBI) and plasma iron to three different oral iron compounds—ferrous sulfate, sodium iron ethylenediaminetetraacetate (NaFeEDTA), and iron polymaltose (IPM)—in women with marginal iron stores.

Methods

Serum samples from 10 Guatemalan women with marginal iron stores were collected every 90 minutes over a period of 270 minutes, after the individually randomized administration of 100 mg of iron from each of the three studied iron compounds or water alone. Serum iron concentration was quantified by the ferrozine method, and circulating NTBI concentration was determined with a fluorometric competitive binding assay. Kinetic responses and maximal cumulative changes in serum concentrations of iron and NTBI were compared between the four treatments. Comparison was made with data from the same protocol in iron-adequate men.

Results

The serum iron and NTBI responses to ferrous sulfate were significantly greater than those to water and the other two iron compounds. Serum iron responses to IPM did not differ from those to water alone.

Conclusions

The administration of the two “slow-release” iron compounds, NaFeEDTA and IPM, resulted in a highly significant suppression of the appearance of NTBI in the circulation in the postsupplement period. These two bioavailable forms of iron supplement could represent a safe option for supplementation in malarial areas. The slope of the iron—NTBI relationship is steeper in men than in women.

Safety of iron fortification and supplementation in malaria-endemic areas

This review considers the safety of iron supplementation and fortification for the prevention and correction of iron deficiency in malaria-endemic areas, with a focus on potential means whereby provision of additional iron might heighten the risks of malaria and other infections. Iron deficiency itself may increase the risk of morbidity and mortality from malaria and other infections. The available evidence indicates that iron interventions are safe in settings without endemic malaria, and, with adequate health care, in regions with high transmission of malaria and other infections. Without regular surveillance and treatment of malaria and other infections, iron supplementation of individuals who are iron deficient seems safe, but individuals who are iron replete may have an increased risk of adverse outcomes. The mechanisms responsible for harmful effects with iron supplementation have not been established. These are likely to include the effects of (a) increased amounts of absorbed iron, with the production of plasma non-transferrin-bound iron, (b) increased amounts of iron in the gastrointestinal tract, with effects on gastrointestinal structural integrity and on gut microflora, and (c) the complex immune effects of iron interventions. Iron fortification appears to be generally safe, although more data from malaria-endemic areas are needed.

Iron requirements based upon iron absorption tests are poorly predicted by haematological indices in patients with inactive inflammatory bowel disease

Fe deficiency and Fe-deficiency anaemia are common in patients with inflammatory bowel disease (IBD). Traditional clinical markers of Fe status can be skewed in the presence of inflammation, meaning that a patient's Fe status can be misinterpreted. Additionally, Fe absorption is known to be down-regulated in patients with active IBD. However, whether this is the case for quiescent or mildly active disease has not been formally assessed. The present study aimed to investigate the relationship between Fe absorption, Fe requirements and standard haematological indices in IBD patients without active disease. A group of twenty-nine patients with quiescent or mildly active IBD and twenty-eight control subjects undertook an Fe absorption test that measured sequential rises in serum Fe over 4 h following ingestion of 200 mg ferrous sulphate. At baseline, serum Fe, transferrin saturation, non-transferrin-bound Fe (NTBI), ferritin and soluble transferrin receptor were all measured. Thereafter (30-240 min), only serum Fe and NTBI were measured. Fe absorption did not differ between the two groups (P = 0·9; repeated-measures ANOVA). In control subjects, baseline haematological parameters predicted Fe absorption (i.e. Fe requirements), but this was not the case for patients with IBD. Fe absorption is normal in quiescent or mildly active IBD patients but standard haematological parameters do not accurately predict Fe requirements.

Safety and efficacy of iron supplements in malaria-endemic areas

Where malaria surveillance and health care is inadequate, iron supplements given without food can increase the severity of malarial infections. The likely explanation is that the rate of iron influx into the plasma from high-dose oral supplements exceeds the rate of iron binding to transferrin and a quantity of non-transferrin-bound iron (NTBI) is formed. It is proposed that NTBI increases the intensity of malarial infections by increasing the sequestration of malaria-infected red cells in the capillaries of the brain and intestine, causing more cerebral malaria and further increasing the permeability of the intestinal barrier to the passage of pathogens. Bacteremia is frequently reported in children with severe malaria. At the same time, high iron doses stimulate the growth of pathogenic bacteria in the stool, further increasing the potential for bacteremia. The normal immune response to malaria, as well as other infections and inflammatory disorders, is to prevent further microbial growth by stimulating hepcidin synthesis and preventing the passage of iron into the plasma. Iron absorption is decreased and the efficacy of the iron interventions would be expected to be lower in the presence of infections.

Effect of supplementation with zinc and other micronutrients on malaria in Tanzanian children: a randomised trial

BACKGROUND

It is uncertain to what extent oral supplementation with zinc can reduce episodes of malaria in endemic areas. Protection may depend on other nutrients. We measured the effect of supplementation with zinc and other nutrients on malaria rates.

METHODS AND FINDINGS

In a 2×2 factorial trial, 612 rural Tanzanian children aged 6-60 months in an area with intense malaria transmission and with height-for-age z-score≤-1.5 SD were randomized to receive daily oral supplementation with either zinc alone (10 mg), multi-nutrients without zinc, multi-nutrients with zinc, or placebo. Intervention group was indicated by colour code, but neither participants, researchers, nor field staff knew who received what intervention. Those with Plasmodium infection at baseline were treated with artemether-lumefantrine. The primary outcome, an episode of malaria, was assessed among children reported sick at a primary care clinic, and pre-defined as current Plasmodium infection with an inflammatory response, shown by axillary temperature ≥37.5°C or whole blood C-reactive protein concentration ≥ 8 mg/L. Nutritional indicators were assessed at baseline and at 251 days (median; 95% reference range: 191-296 days). In the primary intention-to-treat analysis, we adjusted for pre-specified baseline factors, using Cox regression models that accounted for multiple episodes per child. 592 children completed the study. The primary analysis included 1,572 malaria episodes during 526 child-years of observation (median follow-up: 331 days). Malaria incidence in groups receiving zinc, multi-nutrients without zinc, multi-nutrients with zinc and placebo was 2.89/child-year, 2.95/child-year, 3.26/child-year, and 2.87/child-year, respectively. There was no evidence that multi-nutrients influenced the effect of zinc (or vice versa). Neither zinc nor multi-nutrients influenced malaria rates (marginal analysis; adjusted HR, 95% CI: 1.04, 0.93-1.18 and 1.10, 0.97-1.24 respectively). The prevalence of zinc deficiency (plasma zinc concentration <9.9 µmol/L) was high at baseline (67% overall; 60% in those without inflammation) and strongly reduced by zinc supplementation.

CONCLUSIONS

We found no evidence from this trial that zinc supplementation protected against malaria.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00623857

Efficacy, Tolerability, and Acceptability of Iron Hydroxide Polymaltose Complex versus Ferrous Sulfate: A Randomized Trial in Pediatric Patients with Iron Deficiency Anemia

Iron polymaltose complex (IPC) offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA) were randomized to IPC once daily or ferrous sulfate twice daily, (both 5 mg iron/kg/day). Mean increases in Hb to months 1 and 4 with IPC were 1.2 ± 0.9 g/dL and 2.3 ± 1.3 g/dL, respectively, (both P = 0.001 versus baseline) and 1.8 ± 1.7 g/dL and 3.0 ± 2.3 g/dL with ferrous sulfate (both P = 0.001 versus baseline) (n.s. between groups). Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P = 0.012). Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63 ± 0.56 versus 2.14 ± 0.75, P = 0.001). Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability.

Transfusion of human volunteers with older, stored red blood cells produces extravascular hemolysis and circulating non-transferrin-bound iron

Transfusions of RBCs stored for longer durations are associated with adverse effects in hospitalized patients. We prospectively studied 14 healthy human volunteers who donated standard leuko-reduced, double RBC units. One unit was autologously transfused "fresh" (3-7 days of storage), and the other "older" unit was transfused after 40 to 42 days of storage. Of the routine laboratory parameters measured at defined times surrounding transfusion, significant differences between fresh and older transfusions were only observed in iron parameters and markers of extravascular hemolysis. Compared with fresh RBCs, mean serum total bilirubin increased by 0.55 mg/dL at 4 hours after transfusion of older RBCs (P = .0003), without significant changes in haptoglobin or lactate dehydrogenase. In addition, only after the older transfusion, transferrin saturation increased progressively over 4 hours to a mean of 64%, and non-transferrin-bound iron appeared, reaching a mean of 3.2μM. The increased concentrations of non-transferrin-bound iron correlated with enhanced proliferation in vitro of a pathogenic strain of Escherichia coli (r = 0.94, P = .002). Therefore, circulating non-transferrin-bound iron derived from rapid clearance of transfused, older stored RBCs may enhance transfusion-related complications, such as infection.

Harmful effects of transfusion of older stored red blood cells: iron and inflammation

Retrospective studies suggest that the transfusion of older, stored red blood cells (RBCs) may be associated with increases in mortality, serious infections, multiorgan failure, thrombosis, and hospital length of stay. Our research is based on the overarching hypothesis that the adverse effects associated with transfusion of older, stored RBCs result from the acute delivery of hemoglobin iron to the monocyte-macrophage system. To test this "iron hypothesis," we are recruiting healthy human volunteers to donate double, leukoreduced, RBC units. We then transfuse them with one autologous fresh unit (i.e., after 3-7 days of storage) and one older, stored unit (i.e., at 40-42 days of storage). The primary study outcome will compare laboratory iron measures and proinflammatory cytokines after transfusion of fresh or older, stored RBCs. Similar studies using allogeneic RBC transfusions will be performed in chronically transfused patients with either sickle cell disease or β-thalassemia. Although prospective, randomized studies will ultimately determine the existence of adverse effects from transfusing older, stored RBCs, our goal is to determine the mechanism(s) for this potential effect.

Fortification iron as ferrous sulfate plus ascorbic acid is more rapidly absorbed than as sodium iron EDTA but neither increases serum nontransferrin-bound iron in women

The absorption profile of iron fortificants may be a determinant of their ability to generate nontransferrin-bound iron (NTBI) and, thus, their potential safety. Ferrous iron may be absorbed more rapidly than chelated ferric iron, but differences at the fortification level cannot be distinguished with nonisotopically labeled serum iron curves. Using stable isotope appearance curves (SIAC) in serum, we measured iron absorption profiles from FeSO(4) with ascorbic acid (AA) and from NaFeEDTA, as well as the serum hepcidin and NTBI response following the meals. Healthy women (n = 16) were given 6 mg oral iron as labeled FeSO(4) and NaFeEDTA with a maize porridge using a crossover design. SIAC, NTBI, and serum hepcidin were measured over 8 h after the meal. Iron from FeSO(4) plus AA was more rapidly absorbed, resulting in a 35% greater relative AUC during the first 2 h than for NaFeEDTA (P < 0.001). Median (95% CI) fractional iron absorption from the FeSO(4)- and NaFeEDTA-fortified meals was 15.2% (11.0-19.5) and 6.0% (5.0-9.2), respectively (P < 0.001). In response to the FeSO(4)-fortified meal, there was an ~60% increase in median serum hepcidin (P < 0.05) but no significant change in NTBI. There was no significant change in serum hepcidin or NTBI after the NaFeEDTA-fortified meal. SIAC are a useful new tool to compare iron absorption profiles from different iron compounds in fortified foods. Even with the use of a very well absorbed ferrous iron compound, iron fortification in this population does not increase NTBI, suggesting a low risk for adverse health consequences.

Expert recommendations for the diagnosis and treatment of iron-deficiency anemia during pregnancy and the postpartum period in the Asia-Pacific region

Anemia during pregnancy and the postpartum period is commonly caused by iron deficiency and is a significant worldwide issue with severe consequences for both mother and developing fetus. From a worldwide perspective, iron-deficiency anemia (IDA) during pregnancy is highest in the Asia-Pacific region; however, there has been little guidance in this region for safe and effective treatment. An expert panel was convened to develop a concise and informative set of recommendations for the treatment of IDA in pregnant and postpartum women in the Asia-Pacific region. This manuscript provides these recommendations and aims to reduce the morbidity and mortality associated with IDA in pregnant and postpartum women in the Asia-Pacific region. The consensus recommendations define anemia as a hemoglobin (Hb) level <10.5 g/dL during pregnancy and <10 g/dL during the postpartum period, and provide cut-off Hb levels to initiate therapy with oral iron, intravenous iron or red blood cell transfusion.

The pharmacokinetics and pharmacodynamics of iron preparations

Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3–4 weeks. Accordingly, serum iron concentration and area under the curve (AUC) are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III)-hydroxide complexes with carbohydrate ligands or orally as iron(II) (ferrous) salts or iron(III) (ferric) complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.