Non-anaemic iron deficiency - a disease looking for recognition of diagnosis: a systematic review

Nonanemic Iron Deficiency in Cardiac Surgery: A Retrospective Observational Study

OBJECTIVES

Anemia and iron deficiency in patients having cardiac surgery increases their perioperative risk. Nonanemic iron deficiency (NAID) in this group is less well-described. We aimed to investigate the incidence and outcomes of patients with NAID undergoing cardiac surgery.

DESIGN

Retrospective observational study.

SETTING

A single, tertiary referral center.

PARTICIPANTS

Adult patients who were preassessed and underwent cardiac surgery during the study period had data collected. We enrolled 537 patients enrolled and divided them into 4 groups according to hemoglobin and ferritin: NAID, nonanemic iron replete, iron-deficiency anemia (IDA), and non-iron-deficiency anemia.

INTERVENTIONS

This study was not interventional, but assessed the impact of anemia and iron deficiency on patient outcomes.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the incidence of NAID. Secondary outcomes included the number of patients who became anemic awaiting surgery, allogeneic transfusion burden, length of stay, postoperative complications, and death. 179 of 537 patients (33.3%) had NAID. Seventeen patients (9.5%) became anemic in the NAID group compared with 7 (3.3%) in the nonanemic iron replete group while awaiting for surgery (p = 0.02). Patients with NAID were more likely to receive allogeneic transfusions (33% vs 23%; p = 0.04) and had poorer recovery of hemoglobin at follow-up (13.2 ± 1.46 g/dL vs 13.9 ± 1.46 g/dL; p < 0.001).

CONCLUSIONS

NAID is common and can lead to progression to anemia and increased transfusion. Iron replacement should be considered in patients with NAID in the preoperative setting. A prospective interventional trial is required to demonstrate the benefit of being iron replete.

Evaluating utility of routine ferritin testing in blood donors: A hospital-based blood donor centre experience

BACKGROUND AND OBJECTIVES

Iron deficiency (ID) poses a prevalent concern among blood donors, especially impacting young donors, premenopausal females and frequent donors. In alignment with recommendations to address ID, routine ferritin testing was implemented in a hospital-based donor centre.

MATERIALS AND METHODS

Data set, encompassing 26 164 ferritin values from 16 464 blood donors over 33 months, were analysed retrospectively. Ferritin levels were assessed concerning donor characteristics such as sex, age, ethnicity and donation frequency.

RESULTS

Ferritin testing revealed age, sex and ethnicity variations, emphasising the heightened risk of ID in young females meeting all donation criteria under 23 year of age who demonstrated the lowest mean baseline ferritin (41% [CI: 34%-48%] < 26 ng/mL; 20% [CI: 14%-25%] < 15 ng/mL). Postmenopausal females exhibited ferritin levels similar to similarly aged males. Irrespective of sex, donors showcased mean ferritin recovery within 6 months. Analysis of ferritin recovery post-donation showed a five-fold increase in risk (compared with first visit) of ID when donors return at a 2-month interval. 'Regular' donors (≥10 visits) approach a median steady ferritin level (~30-35 ng/mL) by the sixth visit.

CONCLUSION

As reliance on regular blood donors increases, donation policies must strike a balance between blood centre resources and the risks posed to both regular and at-risk donors. Frequent blood donation led to donors attaining a mean steady state ferritin level above the threshold for ID. At-risk groups, particularly premenopausal females, were several times more likely to experience ID after donation but demonstrated recovery rates similar to their group's baseline levels. This valuable information informed the development of new donor deferral policies.

Iron deficiency-related symptoms in non-anemic whole blood donors

INTRODUCTION

Whole blood donors are at increased risk for iron deficiency (ID). ID anemia is associated with several symptoms, such as fatigue, cognitive dysfunction, pica, and restless leg syndrome (RLS). However, it is unclear if these symptoms also occur when a donor has developed ID without anemia. This study aims to determine whether non-anemic ID (NAID) is associated with the occurrence of ID-related symptoms.

STUDY DESIGNS AND METHODS

We combined data from three studies in whole blood donors (i.e., Donor Insight-III, FIND'EM, and FORTE) to create a substantial sample size (N = 12,143). The self-reported occurrence and severity of ID-related symptoms, such as physical and mental health, fatigue, cognitive functioning, pica, and RLS, was measured using validated questionnaires. Associations were studied using logistic regression modeling with ID-related symptoms derived from the questionnaires as the dependent variable and ferritin level group (0-15 μg/L, 15-30 μg/L, and >30 μg/L) as explanatory variable.

RESULTS

After applying inclusion and exclusion criteria, 9829 donors were eligible for analysis. In the models corrected for age, body mass index, Hb level, and cohort, only fatigue was shown to be associated with ferritin levels in men, showing lower odds (OR 1.41, 95% CI 1.11-1.79) for fatigue with higher ferritin levels.

CONCLUSION

In these studies, NAID was only associated with self-reported fatigue in male donors. Although selection bias may have led to underestimated associations, ferritin measurements in donors should be primarily considered as a measure to prevent anemia, rather than to prevent or mitigate NAID-related symptoms.

Analysis of erythrocyte and iron study data among plateletpheresis donors in Hangzhou, China

BACKGROUND

The purpose of this study is to obtain the iron parameters level of blood donors and the population who need to pay attention to iron parameters level in this area.

METHODS

A total of 993 plateletpheresis donors were included in this study, including 798 males and 195 females. The results of erythrocyte and iron parameters of blood donors were compared and analyzed in different groups according to the gender, age and number of blood donations.

RESULT

The proportion of men and women with low serum ferritin (SF) levels was 10.8 % and 27.7 %, respectively. The mean levels of serum iron (SI), SF, transferrin saturation (Tfs), hemoglobin (Hb) and hematocrit (HCT) of male blood donors decreased with the increase of age groups, but there was no significant statistical difference between the results of female blood donors. The level of SI, SF, Tfs, Hb and HCT of male donors decreased with the increase of blood donations in the past year, while TRF and TIBC increased. The level of Hb, HCT and SF of female donors showed no significant downward trend, while the levels of TRF increased with increasing donations in the past year, excluding first-time donors. The SI of female donors trended down, and TIBC trended up with increasing donations.

CONCLUSION

Blood collection institutions need to focus on iron parameters levels in older and frequent male donors, and young fertile female donors.

Effectiveness of ferritin-guided donation intervals in whole-blood donors in the Netherlands (FIND'EM): a stepped-wedge cluster-randomised trial

BACKGROUND

Whole-blood donors are at increased risk for iron deficiency and anaemia. The current standard of haemoglobin monitoring is insufficient to ensure the maintenance of proper iron reserves and donor health. We aimed to determine the effects of ferritin-guided donation intervals for blood donor health and blood supply in the Netherlands.

METHODS

In this stepped-wedge cluster-randomised trial (FIND'EM), the 138 fixed and mobile donation centres in the Netherlands are organised into 29 geographical clusters and the clusters were randomly assigned to four treatment groups, with two groups being further split into two per a protocol amendment. Eligible donors were whole-blood donors who consented for use of their leftover material in the study. Each group was sequentially crossed over from the existing policy (haemoglobin-based screening; control) to a ferritin-guided donation interval policy over a 3-year period. In the intervention groups, in addition to the existing haemoglobin screening, ferritin was measured in all new donors and at every fifth donation in repeat donors. Subsequent donation intervals were extended to 6 months if ferritin concentrations were 15-30 ng/mL and to 12 months if they were less than 15 ng/mL. Outcomes were measured cross-sectionally across all donation centres at four timepoints. Primary outcomes were ferritin and haemoglobin concentrations, iron deficiency, and haemoglobin-based deferrals. We assessed all outcomes by sex and menopausal status and significance for primary outcomes was indicated by a p value of less than 0·0125. This trial is registered in the Dutch trial registry, NTR6738, and is complete.

FINDINGS

Between Sept 11, 2017, and Nov 27, 2020, 412 888 whole-blood donors visited a donation centre, and we did measurements on samples from 37 621 donations from 36 099 donors. Over 38 months, ferritin-guided donation intervals increased mean ferritin concentrations (by 0·18 log10 ng/mL [95% CI 0·15-0·22; p<0·0001] in male donors, 0·10 log10 ng/mL [0·06-0·15; p<0·0001] in premenopausal female donors, and 0·17 log10 ng/mL [0·12-0·21; p<0·0001] in postmenopausal female donors) and mean haemoglobin concentrations (by 0·30 g/dL [95% CI 0·22-0·38; p<0·0001] in male donors, 0·12 g/dL [0·03-0·20; p<0·0074] in premenopausal female donors, and 0·16 g/dL [0·05-0·27; p<0·0044] in postmenopausal female donors). Iron deficiency decreased by 36-38 months (odds ratio [OR] 0·24 [95% CI 0·18-0·31; p<0·0001] for male donors, 0·49 [0·37-0·64; p<0·0001] for premenopausal female donors, and 0·24 [0·15-0·37; p<0·0001] for postmenopausal female donors). At 36-38 months, haemoglobin-based deferral decreased significantly in male donors (OR at 36-38 months 0·21 [95% CI 0·10-0·40, p<0·0001]) but not significantly in premenopausal or postmenopausal female donors (0·81 [0·54-1·20; p=0·29] and 0·50 [95% CI 0·25-0·98; p=0·051], respectively).

INTERPRETATION

Ferritin-guided donation intervals significantly improved haemoglobin and ferritin concentrations and significantly decreased iron deficiency over the study period. Haemoglobin-based deferrals decreased significantly for male donors, but not female donors. Although this intervention is overall beneficial for maintenance of iron and haemoglobin concentrations in donors, increased efforts are needed to recruit and retain donors.

FUNDING

The Sanquin Research Programming Committee.

Identification and management of preoperative anaemia in adults: A British Society for Haematology Guideline update

This updated British Society for Haematology guideline provides an up-to-date literature review and recommendations regarding the identification and management of preoperative anaemia. This includes guidance on thresholds for the diagnosis of anaemia and the diagnosis and management of iron deficiency in the preoperative context. Guidance on the appropriate use of erythropoiesis-stimulating agents and preoperative transfusion is also provided.

The origin of ferritin reference intervals: a systematic review

Iron deficiency is a highly prevalent condition, which contributes to unnecessary morbidity, mortality, and health inequity. A serum ferritin concentration of less than 30 μg/L has a high specificity and sensitivity for diagnosing iron deficiency in adults, but the laboratory reported lower limit of normal (LLN) is typically lower. These LLNs might not be rooted in rigorous scientific evidence and might be contributing to structural underdiagnosis of iron deficiency. A systematic review was done per systematic reviews and meta-analysis guidelines with the use of medical literature databases from inception of each database to Nov 30, 2021, to identify studies that determined ferritin reference intervals in healthy adults and grey literature search for the five most common ferritin assays (registration number CRD42022268844). The objectives were to systematically summarise the ferritin reference intervals and to do a methodological quality assessment of the included studies. 2306 studies were screened and 61 full texts were included. 37 studies were eligible for analysis of the ferritin LLN in the general population. The population the sample was comprised of was a total of 21 882 females and 23 650 males participants. The ferritin LLN was a median of 8 μg/L (IQR 5-15) and mean of 9 μg/L (SD 11) in females and a median of 25 μg/L (IQR 16-44) and mean of 25 μg/L (SD 29) in males. 30 (49%) of 61 studies did not explicitly screen for patients at risk of iron deficiency, and 32 (52%) did not refer to a reference interval establishment guideline (eg, guideline recommended by Clinical and Laboratory Standards Institute). The five most used commercial ferritin laboratory assays reported reference intervals with a median LLN of 11 (IQR 9-12) and mean of 9 μg/L (SD 4) for females and median of 22 (IQR 22-24) and mean of 23 μg/L (SD 4) for males. In the literature, serum ferritin reference intervals in healthy adults consistently report a LLN of less than 30 μg/L. Data driving these ferritin reference intervals are at high risk of bias, given no exclusion of individuals at risk for iron deficiency in the presumed normal population sample and no adherence to reference interval establishment standards. We suggest the use of evidence-based laboratory clinical decision limits to diagnose iron deficiency.

Rusfertide, a Hepcidin Mimetic, for Control of Erythrocytosis in Polycythemia Vera

BACKGROUND

Polycythemia vera is a chronic myeloproliferative neoplasm characterized by erythrocytosis. Rusfertide, an injectable peptide mimetic of the master iron regulatory hormone hepcidin, restricts the availability of iron for erythropoiesis. The safety and efficacy of rusfertide in patients with phlebotomy-dependent polycythemia vera are unknown.

METHODS

In part 1 of the international, phase 2 REVIVE trial, we enrolled patients in a 28-week dose-finding assessment of rusfertide. Part 2 was a double-blind, randomized withdrawal period in which we assigned patients, in a 1:1 ratio, to receive rusfertide or placebo for 12 weeks. The primary efficacy end point was a response, defined by hematocrit control, absence of phlebotomy, and completion of the trial regimen during part 2. Patient-reported outcomes were assessed by means of the modified Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) patient diary (scores range from 0 to 10, with higher scores indicating greater severity of symptoms).

RESULTS

Seventy patients were enrolled in part 1 of the trial, and 59 were assigned to receive rusfertide (30 patients) or placebo (29 patients) in part 2. The estimated mean (±SD) number of phlebotomies per year was 8.7±2.9 during the 28 weeks before the first dose of rusfertide and 0.6±1.0 during part 1 (estimated difference, 8.1 phlebotomies per year). The mean maximum hematocrit was 44.5±2.2% during part 1 as compared with 50.0±5.8% during the 28 weeks before the first dose of rusfertide. During part 2, a response was observed in 60% of the patients who received rusfertide as compared with 17% of those who received placebo (P = 0.002). Between baseline and the end of part 1, rusfertide treatment was associated with a decrease in individual symptom scores on the MPN-SAF in patients with moderate or severe symptoms at baseline. During parts 1 and 2, grade 3 adverse events occurred in 13% of the patients, and none of the patients had a grade 4 or 5 event. Injection-site reactions of grade 1 or 2 in severity were common.

CONCLUSIONS

In patients with polycythemia vera, rusfertide treatment was associated with a mean hematocrit of less than 45% during the 28-week dose-finding period, and the percentage of patients with a response during the 12-week randomized withdrawal period was greater with rusfertide than with placebo. (Funded by Protagonist Therapeutics; REVIVE ClinicalTrials.gov number, NCT04057040.).

Factors Associated with Anemia and Iron Deficiency during Pregnancy: A Prospective Observational Study in Japan

Gestational anemia (GA) is a global health concern with a remarkably high prevalence in Japan, which is associated with various maternal and neonatal outcomes. This study aimed to explore whether GA and non-anemic iron deficiency (NAID) during the third trimester is associated with maternal characteristics, nutrient intake, low birth weight (LBW), and preterm birth. Participants were categorized into GA, NAID, and normal groups, based on serum ferritin and hemoglobin levels. Nutrient intake was assessed using the Brief Diet History Questionnaire. Data from 317 pregnant women were analyzed, including 110 (34.7%), 151 (47.6%), and 56 (17.6%) women in the GA, NAID, and normal groups, respectively. Factors associated with GA included being multipara (p < 0.001) and not taking any type of iron supplements in the third trimester (p = 0.043). The normal group had a significantly higher proportion of preterm birth and LBW than the GA and NAID groups. The GA group had a significantly higher energy intake than the normal group (p = 0.044). Overall, energy and micronutrient intake were significantly below the estimated average requirement in the dietary reference intakes for Japanese. Health care professionals need to consider nutritional advice that can prevent GA by focusing on overall micronutrients, not just energy intake.

Cytoreduction for ET and PV: who, what, when, and how?

Thrombotic complications are the primary contributor to morbidity and mortality in essential thrombocythemia (ET) and polycythemia vera (PV). Cytoreductive therapy is the main tool for primary or tertiary thrombosis prevention in these diseases. In general, high-thrombotic-risk patients and those with symptoms that may be ameliorated from cytoreductive therapy are candidates for this treatment, although the decision is highly individualized. Approved options for cytoreduction in ET and PV include hydroxyurea, long-acting interferons, anagrelide in ET, and ruxolitinib in PV. Selecting the ideal agent requires careful consideration of the toxicity profiles and individual treatment goals. In this review the existing literature on cytoreductive decisions in ET and PV is summarized, with an emphasis on risk-stratification, highlighting the need for personalized care in order to maximize the benefit of these therapies while minimizing toxicities.

Real-world experience of intravenous iron sucrose supplementation and dynamics of soluble transferrin receptor and hepcidin in a Spanish cohort of absolute iron deficient patients

The study evaluated the safety and effectiveness of the generic intravenous (IV) iron treatment (Feriv®), in a Spanish cohort with absolute iron deficiency (ID) (serum ferritin <50 ng/ml, with or without anaemia) (n = 122; 91% women; median age of 44 years [IQR: 33.7-54]). Iron-related biomarkers were measured before treatment (baseline), 2 weeks after beginning the protocol (intermediate control, IC) and between 7 and 10 days after treatment completion (final time-point). Primary efficacy endpoints were ferritin levels ≥ 50 ng/ml, anaemia restoration or an increase in haemoglobin (Hb) of at least one point in patients without baseline anaemia. After treatment, iron-related biomarkers improved, including ferritin, Hb, sideremia, transferrin, transferrin saturation index, soluble transferrin receptor (sTfR), and hepcidin. Baseline ferritin concentration (13.5 ng/ml [IQR: 8-24.2]) increased at the IC and continued rising at the final time-point, reaching a median ferritin of 222 ng/ml and 97.3% of patients ≥ 50 ng/ml. At the final time-point, anaemia prevalence decreased from 26.2% to 5%, while the 34.1% without baseline anaemia showed an increase in Hb of at least one point. Headache was the only drug-adverse event recorded in 2.3% of patients. At a late time-point (27.5 median weeks after ending therapy [IQR: 22-40]), evaluated in a subgroup of 66 patients, 18% had ferritin levels < 50 ng/ml. Multivariate analysis showed that low baseline ferritin and high sTfR/hepcidin ratio tended to be independently associated with ID recurrence. Feriv® is a safe, effective first-line treatment for absolute ID, with improvement of serum ferritin and Hb. ID recurrence was associated with the baseline degree of iron stores depletion, indicated by serum ferritin, and sTfR/hepcidin ratio.

Standardising outcome reporting for clinical trials of interventions for heavy menstrual bleeding: Development of a core outcome set

OBJECTIVE

To develop a core outcome set for heavy menstrual bleeding (HMB).

DESIGN

Core outcome set (COS) development methodology described by the COMET initiative.

SETTING

University hospital gynaecology department, online international survey and web-based international consensus meetings.

POPULATION OR SAMPLE

An international collaboration of stakeholders (clinicians, patients, academics, guideline developers) from 20 countries and 6 continents.

METHODS

Phase 1: Systematic review of previously reported outcomes to identify potential core outcomes. Phase 2: Qualitative studies with patients to identify outcomes most important to them. Phase 3: Online two-round Delphi survey to achieve consensus about which outcomes are most important. Phase 4: A consensus meeting to finalise the COS.

MAIN OUTCOME MEASURES

Outcome importance was assessed in the Delphi survey on a 9-point scale.

RESULTS

From the 'long list' of 114, 10 outcomes were included in the final COS: subjective blood loss; flooding; menstrual cycle metrics; severity of dysmenorrhoea; number of days with dysmenorrhoea; quality of life; adverse events; patient satisfaction; number of patients going on to have further treatment for HMB and haemoglobin level.

CONCLUSIONS

The final COS includes variables that are feasible for use in clinical trials in all resource settings and apply to all known underlying causes of the symptom of HMB. These outcomes should be reported in all future trials of interventions, their systematic reviews, and clinical guidelines to underpin policy.

Normal and dysregulated crosstalk between iron metabolism and erythropoiesis

Erythroblasts possess unique characteristics as they undergo differentiation from hematopoietic stem cells. During terminal erythropoiesis, these cells incorporate large amounts of iron in order to generate hemoglobin and ultimately undergo enucleation to become mature red blood cells, ultimately delivering oxygen in the circulation. Thus, erythropoiesis is a finely tuned, multifaceted process requiring numerous properly timed physiological events to maintain efficient production of 2 million red blood cells per second in steady state. Iron is required for normal functioning in all human cells, the erythropoietic compartment consuming the majority in light of the high iron requirements for hemoglobin synthesis. Recent evidence regarding the crosstalk between erythropoiesis and iron metabolism sheds light on the regulation of iron availability by erythroblasts and the consequences of insufficient as well as excess iron on erythroid lineage proliferation and differentiation. In addition, significant progress has been made in our understanding of dysregulated iron metabolism in various congenital and acquired malignant and non-malignant diseases. Finally, we report several actual as well as theoretical opportunities for translating the recently acquired robust mechanistic understanding of iron metabolism regulation to improve management of patients with disordered erythropoiesis, such as anemia of chronic inflammation, β-thalassemia, polycythemia vera, and myelodysplastic syndromes.

Sucrosomial® Iron: An Updated Review of Its Clinical Efficacy for the Treatment of Iron Deficiency

Iron deficiency (ID) and iron deficiency anemia (IDA) are highly prevalent worldwide. Oral iron salts, especially ferrous sulfate, are commonly used for the treatment of iron deficiency (ID). However, its use is associated with gastrointestinal side effects, thus compromising treatment compliance. Intravenous iron administration is a more costly and logistically complex alternative and is not risk-free, as infusion and hypersensitivity reactions may occur. Sucrosomial^® iron is an oral formulation consisting of ferric pyrophosphate conveyed by a phospholipid and sucrester matrix (sucrosome^®). Intestinal Sucrosomial^® iron absorption is mediated by enterocytes and M cells, through the paracellular and transcellular routes, and occurs mostly as intact particles. These pharmacokinetic properties of Sucrosomial^® iron result in higher iron intestinal absorption and excellent gastrointestinal tolerance compared to oral iron salts. The evidence derived from clinical studies supports the use of Sucrosomial^® iron as a valid first option for the treatment of ID and IDA, especially for subjects who are intolerant or refractory to conventional iron salts. Newer evidence also demonstrates the effectiveness of Sucrosomial^® iron, with a lower cost and fewer side effects, in certain conditions usually treated with IV iron in current clinical practice.

Sucrosomial® iron effectiveness in recovering from mild and moderate iron-deficiency anemia in the postpartum period

BACKGROUND

Postpartum iron deficiency anemia (PPIDA) is highly prevalent in developing countries where it constitutes an important cause of maternal morbidity and mortality. Potential determinants of PPIDA are prepartum iron deficiency or iron deficiency anemia in association with severe blood loss during delivery. We investigated the efficacy of oral Sucrosomial® iron for recover from mild-to-moderate PPIDA.

METHODS

This pilot study was conducted in three medical centers in Romania. Adult women (≥ 18y) with mild (hemoglobin [Hb] 9-11 g/dL) or moderate (Hb 7-9 g/dL) PPIDA diagnosed at screening (2-24 h after delivery) were eligible. Women with mild PPIDA received oral Sucrosomial® iron (Pharmanutra, S.p.A, Italy) once daily (30 mg elemental iron per capsule) for 60 days. Those with moderate PPIDA received oral Sucrosomial® iron twice daily (60 mg elemental iron) for 10 days, followed by a 50-day course of oral Sucrosomial® iron once daily (30 mg elemental iron). Laboratory parameters, as well as subjective clinical symptoms using a 3-point Likert Scale, were assessed at baseline and on study days 10, 30 and 60.

RESULTS

Sixty anemic women entered the study, but three were missed during follow-up. At day 60, a Hb rise was observed in both groups (+ 3.6 ± 1.5 g/dL; p < 0.01), 81% experienced correction of anemia (Hb ≥ 12 g/dL), 36% achieved a ferritin concentration ≥ 30 ng/mL (p < 0.05), and 54% a transferrin saturation (TSAT) ≥ 20% (p < 0.01). For women still anemic at day 60, mean Hb was close to normality (11.3 ± 0.8 g/dL). Resolution of IDA-associated clinical symptoms was already observed just 10 days after treatment initiation. No patient discontinued treatment due to gastrointestinal adverse events.

CONCLUSIONS

Sucrosomial® iron was shown to be potentially effective and well tolerated at treating mild and moderate PPIDA. These results encourage the use of oral Sucrosomial® iron as a treatment option for PPIDA, but larger studies with longer follow-up are warrant.

Iron Deficiency in Attention-Deficit Hyperactivity Disorder, Autism Spectrum Disorder, Internalizing and Externalizing Disorders, and Movement Disorders

This article reviews the role of iron in brain development and function, with a focus on the association between iron deficiency (ID) and neuropsychiatric conditions. First, we describe how ID is defined and diagnosed. Second, the role of iron in brain development and function is summarized. Third, we review current findings implicating ID in a number of neuropsychiatric conditions in children and adolescents, including attention deficit hyperactivity disorder and other disruptive behavior disorders, depressive and anxiety disorders, autism spectrum disorder, movement disorders, and other situations relevant to mental health providers. Last, we discuss the impact of psychotropic medication on iron homeostasis.

Hepcidin mimetics in polycythemia vera: resolving the irony of iron deficiency and erythrocytosis

PURPOSE OF REVIEW

Development of hepcidin therapeutics has been a ground-breaking discovery in restoring iron homeostasis in several haematological disorders. The hepcidin mimetic, rusfertide, is in late-stage clinical development for treating polycythemia vera patients with a global phase 3 trial [NCT05210790] currently underway. Rusfertide serves as the first possible noncytoreductive therapeutic option to maintain haematocrit control and avoid phlebotomy in polycythemia vera patients. In this comprehensive review, we discuss the pathobiology of dysregulated iron metabolism in polycythemia vera, provide the rationale for targeting the hepcidin-ferroportin axis and elaborate on the preclinical and clinical trial evidence supporting the role of hepcidin mimetics in polycythemia vera.

RECENT FINDINGS

Recently, updated results from two phase 2 clinical trials [NCT04057040 & NCT04767802] of rusfertide (PTG300) demonstrate that the drug is highly effective in eliminating the need for therapeutic phlebotomies, normalizing haematological parameters, repleting iron stores and relieving constitutional symptoms in patients with polycythemia vera. In light of these findings, additional hepcidin mimetic agents are also being evaluated in polycythemia vera patients.

SUMMARY

Hepcidin agonists essentially serve as a 'chemical phlebotomy' and are poised to vastly improve the quality of life for phlebotomy requiring polycythemia vera patients.

A multivariate analysis of the risk of iron deficiency in plateletpheresis donors based on logistic regression

BACKGROUND

The purpose of this study was to analyze the application of individual factors, blood cell related indicators, and blood donation frequency in predicting the risk of iron deficiency of plateletpheresis donors.

METHODS

A total of 801 plateletpheresis donors were included in this study. The relationship between risk factors and iron deficiency was retrospectively analyzed by univariate analysis and logistic regression analysis. The application of Hb, MCHC, RDW-CV and blood donation frequency combined prediction of iron deficiency risk among plateletpheresis donors was evaluated.

RESULT

The rate of iron deficiency in this study was 31.5 % (241/766). The age, gender (the ratio of male donors), red blood cell related indicators, blood donation frequency were statistically different between the normal and iron deficiency group (all P < 0.05). Age, gender, the reciprocal of Hb and MCHC, RDW-CV, total number of blood donation and number of plateletpheresis donation in the past year, these indicators to predict the risk of iron deficiency area under the curve (AUC) were 0.558, 0.672, 0.785, 0.717, 0.599, 0.621, 0.646, respectively. The AUC of these indicators combined to predict the risk of iron deficiency was 0.877, higher than all single indicators. The sensitivity and specificity of these indicators combined in prediction of iron deficiency were 88.89 % and 81.57 %, respectively.

CONCLUSION

Age, gender, the reciprocal of Hb and MCHC, RDV-CV, blood donation frequency are associated with the risk of iron deficiency in plateletpheresis donors. The combination of these indicators has high value in predicting the risk of iron deficiency.

Iron Deficiency and Blood Donation: Links, Risks and Management

The purpose of this review is to raise awareness about the frequently underappreciated association of blood donation with iron deficiency, and to describe methods for its prevention and management. Blood donors cannot expect any health benefits from the donation but have justified expectations of no harm. Iron deficiency without anemia (IDWA) and iron deficiency anemia (IDA) are common consequences of regular blood donation, and this activity is the most important factor affecting iron status in regular blood donors. Awareness of blood donation as a primary cause of sideropenia is surprisingly low among physicians. Blood donation screening identifies potential donors with IDA but is frequently inadequate to detect IDWA. For the assessment of body iron stores, plasma or serum ferritin, transferrin saturation (TSAT) and soluble transferrin receptors (sTfR) concentrations are the most widely used biochemical markers, although the percentage of hypochromic mature erythrocytes and the hemoglobin content of reticulocytes are also useful. IDWA can be prevented by limiting the total volume of blood collected, by iron deficiency screening and deferral of sideropenic donors, by prolonging the interdonation intervals, and by iron supplementation between donations. IDWA tends to be more prevalent in younger people, females, and high-intensity donors. A potentially effective strategy to address sideropenia in blood donors is serum ferritin testing, but this may lead to a higher rate of deferral. Most regular blood donors cannot replenish their iron deficit by an iron-rich diet alone and will benefit from low-dose oral iron administration with various commercially available products post-donation, a well-tolerated strategy. However, valid concerns exist regarding the possibility of worsening the iron overload in donors with undiagnosed hemochromatosis or masking the symptoms of a clinically important gastrointestinal hemorrhage or other underlying medical condition. Finally, educational efforts should be intensified to improve the awareness of blood donation as a primary cause of iron deficiency among physicians of all specialties.

Intravenous Iron Replacement Improves Exercise Tolerance in COPD: A Single-Blind Randomized Trial

INTRODUCTION

Iron deficiency affects exercise capacity because of the critical role iron plays in the optimal functioning of skeletal muscle metabolism. We hypothesized that intravenous iron may improve exercise tolerance, quality of life (QoL), and daily physical activity (DPA) in patients with chronic obstructive pulmonary disease (COPD).

METHODS

This was a placebo-controlled, single-blind, parallel-group, randomized clinical trial. Iron deficiency was defined as a ferritin level<100ng/mL or a ferritin level between 100 and 299ng/mL with a transferrin saturation<20%, with or without mild anaemia. Patients were randomized at a 2:1 ratio to receive intravenous ferric carboxymaltose or placebo. The primary objective was to investigate whether intravenous iron replacement improved endurance time from baseline by at least 33%. The secondary objectives were to evaluate impact on QoL using the COPD Assessment Test (CAT) and on DPA by accelerometry.

RESULTS

We included 66 patients, 44 (66.7%) in the intervention group and 22 (33.3%) in the placebo group. Among patients receiving ferric carboxymaltose, 23 (52.3%) achieved the primary endpoint compared to 4 (18.2%) in the placebo group [p=0.009; relative risk 3.12, (95% CI, 1.19-8.12)]. CAT score decreased -3 (-6.0-1.3) points from baseline in the intervention group (p=0.007), in contrast to placebo group [-1 (-4.0-2.3) points, p=0.236] with no differences in DPA and adverse events in both groups.

CONCLUSIONS

Iron replacement improved exercise capacity and QoL in stable COPD patients with iron deficiency. The treatment was well tolerated.

CLINICAL TRIAL REGISTRATION

EudraCT 2016-001238-89.

Iron deficiency screening is a key issue in chronic inflammatory diseases: A call to action

Iron deficiency is frequent in patients with chronic inflammatory conditions (e.g., chronic heart failure, chronic kidney disease, cancers, and bowel inflammatory diseases). Indeed, high concentrations of inflammatory cytokines increase hepcidin concentrations that lead to the sequestration of iron in cells of the reticuloendothelial system (functional iron deficiency). Iron parameters are often assessed only in the context of anemia, but iron deficiency, even without anemia, is present in about half of patients with inflammatory conditions. Iron deficiency worsens underlying chronic diseases and is an independent factor of morbidity and mortality. In daily practice, the most effective biomarkers of iron status are serum ferritin, which reflects iron storage, and transferrin saturation, which reflects the transport of iron. Serum ferritin is increased in an inflammatory context, and there is still no consensus on the threshold to be used in chronic inflammatory conditions. Nevertheless, recent recommendations of international guidelines agreed to define iron deficiency by serum ferritin &lt;100 µg/L and/or transferrin saturation &lt;20%. Iron parameters remain, however, insufficiently assessed in patients with chronic inflammatory conditions. Indeed, clinical symptoms of iron deficiency, such as fatigue, are not specific and often confused with those of the primary disease. Iron repletion, preferably by the intravenous route to bypass tissue sequestration, improves clinical signs and quality of life. Because of the negative impact of iron deficiency on chronic inflammatory diseases and the efficacy of intravenous iron repletion, screening of iron parameters should be part of the routine examination of all patients with chronic inflammatory diseases.

Maternal iron deficiency anaemia in pregnancy: Lessons from a national audit

We describe the management and the prevalence of iron deficiency anaemia (IDA) during pregnancy by comparison to standards. A cross-sectional national cohort study of women who had given birth six weeks prior to data collection was conducted at maternity units in the UK and Ireland. Participating centres collected data from 10 consecutive pregnant women. Analysis was descriptive to define the prevalence of IDA in pregnancy and the puerperium, and to compare the outcomes in women who had IDA with women who did not have anaemia anytime during pregnancy. Eighty-six maternity units contributed data on 860 pregnancies and births. The overall prevalence of IDA during pregnancy was 30.4% and in the puerperium 20%. Anaemic women were more likely to be from ethnic minorities, odds ratio 2.23 (1.50, 3.32). Adherence to national guidance was suboptimal, and the prevalence of anaemia in pregnancy remains very high. There is pressing need to explore barriers to early identification and effective management of iron deficiency. IDA should be considered a major public health problem in the UK.

Iron Deficiency in Women's Health: New Insights into Diagnosis and Treatment

Iron deficiency (ID), with or without anemia, is commonly found worldwide and affects the health and wellbeing of pregnant and nonpregnant women. Symptoms of ID- which include fatigue, pica (ice craving), restless legs syndrome, poor concentration and work function, increased susceptibility to infection, and cardiovascular stress- can cause significant morbidity and reduced quality of life. The etiologies of iron deficiency in women are usually specific to each community. In the developing world, iron deficiency is usually associated with poor iron intake and parasitic infections, whereas in higher income regions, iron deficiency is typically the result of heavy, abnormal uterine bleeding, and pregnancy. Iron-poor diets and poor iron absorption resulting from gut disorders can also play a role. Diagnosis of iron deficiency is usually straightforward and characterized by a low ferritin level; however, the diagnosis can be challenging in women with concomitant inflammatory disorders, in which case a low percent transferrin saturation, performed after an overnight fast, can inform on the need for iron. Therapy is frequently initiated with oral iron salts; however, use of these oral regimens is commonly associated with adverse events, mostly gastrointestinal in nature, that have been shown to adversely impact compliance, continuation, and the achievement of therapeutic goals. A further impediment to the effectiveness of oral iron is its poor absorption because of comorbidity (i.e., celiac disease, gastritis, etc.), surgery (bariatric), or physiologic inhibitory mechanisms. As such, intravenous (IV) iron regimens are increasingly being used to treat ID, as such regimens have been shown to avoid the gastrointestinal adverse events commonly associated with oral regimens. Indeed, IV iron has been shown to provide adequate iron replacement in women with functional iron deficiencies as well as those with ID resulting from inflammatory disorders- patients often resistant to oral iron therapy. More recent IV iron regimens have been shown to provide iron replacement in a safe and effective manner, being associated with more salutary adverse event profiles than earlier IV iron regimens. In fact, these iron regimens can provide a complete replacement dose in a single 15-60-min visit.

Diagnostic value of reticulocyte indices for the assessment of the iron status of cats with chronic kidney disease

Background

Reticulocyte indices have been suggested as alternatives to transferrin saturation (TSAT) for iron status assessment in humans and dogs but they have not been evaluated thoroughly in cats.

Objectives

To assess the value of the reticulocyte indices for the diagnosis of iron deficiency in cats with chronic kidney disease (CKD) and chronic hematuria associated with subcutaneous ureteral bypasses (SUBs).

Animals

Sixty‐four cats: 16 healthy, 14 CKD without SUB, and 34 CKD with SUB.

Methods

Prospective observational cross‐sectional study of cats presented for routine nephrology visits. Primary outcomes included assessment of the diagnostic values of erythrocyte indices (mean corpuscular volume, hemoglobin, and hemoglobin concentration: MCV, MCH, and MCHC) and reticulocyte indices (mean corpuscular volume, MCVr; corpuscular hemoglobin, CHr), using TSAT as reference.

Results

Iron deficiency was diagnosed in 9/64 cats (14%). A receiver‐operating characteristic curve analysis yielded a moderate discriminatory value for CHr in this diagnosis: area under the curve [AUC] = .75 (95% confidence interval, 0.48‐0.89); P = .006; sensitivity 67%, specificity 82% for a cutoff of 15.9 pg. This compared favorably to MCVr (AUC = .63; P = .29), MCV (AUC = .58; P = .45), MCH (AUC = .64; P = .19), and MCHC (AUC = .7; P = .03).

Conclusion and Clinical Importance

CHr added moderate value to the diagnosis of iron deficiency in cats with CKD.

British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults

Iron deficiency anaemia (IDA) is a major cause of morbidity and burden of disease worldwide. It can generally be diagnosed by blood testing and remedied by iron replacement therapy (IRT) using the oral or intravenous route. The many causes of iron deficiency include poor dietary intake and malabsorption of dietary iron, as well as a number of significant gastrointestinal (GI) pathologies. Because blood is iron-rich it can result from chronic blood loss, and this is a common mechanism underlying the development of IDA-for example, as a consequence of menstrual or GI blood loss.Approximately a third of men and postmenopausal women presenting with IDA have an underlying pathological abnormality, most commonly in the GI tract. Therefore optimal management of IDA requires IRT in combination with appropriate investigation to establish the underlying cause. Unexplained IDA in all at-risk individuals is an accepted indication for fast-track secondary care referral in the UK because GI malignancies can present in this way, often in the absence of specific symptoms. Bidirectional GI endoscopy is the standard diagnostic approach to examination of the upper and lower GI tract, though radiological scanning is an alternative in some situations for assessing the large bowel. In recurrent or refractory IDA, wireless capsule endoscopy plays an important role in assessment of the small bowel.IDA may present in primary care or across a range of specialties in secondary care, and because of this and the insidious nature of the condition it has not always been optimally managed despite the considerable burden of disease- with investigation sometimes being inappropriate, incorrectly timed or incomplete, and the role of IRT for symptom relief neglected. It is therefore important that contemporary guidelines for the management of IDA are available to all clinicians. This document is a revision of previous British Society of Gastroenterology guidelines, updated in the light of subsequent evidence and developments.

Iron Deficiency in CKD Without Concomitant Anemia

The physiological role of iron extends well beyond hematopoiesis. Likewise, the pathophysiological effects of iron deficiency (ID) extend beyond anemia. Although inextricably interrelated, ID and anemia of chronic kidney disease (CKD) are distinct clinical entities. For more than 3 decades, however, nephrologists have focused primarily on the correction of anemia. The achievement of target hemoglobin (Hgb) concentrations is prioritized over repletion of iron stores, and iron status is generally a secondary consideration only assessed in those patients with anemia. Historically, the correction of ID independent of anemia has not been a primary focus in the management of CKD. In contrast, ID is a key therapeutic target in the setting of heart failure (HF) with reduced ejection fraction (HFrEF); correction of ID in this population improves functional status and quality of life and may improve cardiovascular (CV) outcomes. Given the strong interrelationships between HF and CKD, it is reasonable to consider whether iron therapy alone may benefit those with CKD and evidence of ID irrespective of Hgb concentration. In this review, we differentiate anemia from ID by considering both epidemiologic and pathophysiological perspectives and by reviewing the evidence linking correction of ID to outcomes in patients with HF and/or CKD. Furthermore, we discuss existing gaps in evidence and provide proposals for future research and practical considerations for clinicians.

Clinical practice guideline: evidence, recommendations and algorithm for the preoperative optimization of anemia, hyperglycemia and smoking

Preoperative optimization has not been explored comprehensively in the surgical literature, as this responsibility has often been divided among surgery, anesthesia and medicine. We developed an evidence-based clinical practice guideline to summarize existing evidence and present diagnostic and treatment algorithms for use by surgeons caring for patients scheduled to undergo major elective surgery. We focus on 3 common comorbid conditions seen across surgical specialties - anemia, hyperglycemia and smoking - as these conditions increase complication rates in patients undergoing major surgery and can be optimized successfully as soon as 6-8 weeks before surgery. With the ability to address these conditions earlier in the patient journey, surgeons can positively affect patient outcomes. The aim of this guideline is to bring optimization in the preoperative period under the existing umbrella of evidence-based surgical care.

Assessment of analytical bias in ferritin assays and impact on functional reference limits

Serum ferritin is currently the recommended laboratory test to investigate iron deficiency. There have been efforts to standardise serum ferritin assays with implementation of traceability to the World Health Organization reference standard. We evaluate the analytical bias among five widely used commercial ferritin assays in Australia. The relationship between serum ferritin and erythrocyte parameters was recently explored to derive functional reference limits. Residual patient serum specimens were analysed by five participating laboratories that utilised a different ferritin assay, Abbott, Beckman Coulter, Roche, Siemens, and Ortho. Using data mining approach, functional reference limits for Siemens, Abbott, and Ortho serum ferritin methods were derived and compared. At clinically relevant ferritin decision points, compared to the Beckman method, the Roche assay showed higher results ranging from 6 μg/L (31%) at the lowest decision point to 575 μg/L (57%) at the highest decision point. In contrast, the Ortho method underestimated ferritin results at lower decision points of 20 and 30 μg/L, with estimated ferritin results of 16 μg/L (-19%) and 27 μg/L (-12%), respectively. The Abbott and Siemens assays showed a positive bias which was introduced at differing decision points. The comparison of the Siemens and Ortho methods presents similar inflection points between the two assays in the establishment of functional reference limits for serum ferritin. There remain significant biases among some of the commonly used commercial ferritin assays in Australia. More studies are needed to assess if functional reference limits are a way to overcome method commutability issues.

Management Issues and Controversies in Low-Risk Patients with Essential Thrombocythemia and Polycythemia Vera

PURPOSE OF REVIEW

Essential thrombocythemia (ET) and polycythemia vera (PV) are the most common myeloproliferative neoplasms (MPNs). Treatment of ET and PV is based on the risk for subsequent thrombosis. High-risk patients, defined as older than 60, JAK2 V617F-positive patients, or patients with a history of prior thrombosis, merit cytoreduction to control blood counts, whereas a watchful waiting paradigm is utilized in low-risk patients. However, low-risk patients have a host of other specific management issues that arise during their disease course. This review will discuss the most common management issues specific to the care of low-risk patients, including anti-platelet therapy dosing, pregnancy, and indications for early cytoreduction.

RECENT FINDINGS

Although low-dose aspirin is well established in PV, its indications and dosing regimens are less clear in ET. Recent evidence has supported twice daily low-dose aspirin in ET and observation alone in very low-risk ET patients. Pregnancy is not contraindicated in MPNs, and we recommend aspirin throughout pregnancy with consideration for prophylactic postpartum anticoagulation. High phlebotomy needs, symptom burden, and extreme thrombocytosis are common reasons for initiation of cytoreduction in low-risk patients, although we typically do not start cytoreduction for an isolated high platelet count alone. Recent data has also demonstrated a potential disease-modifying effect of interferons in MPNs, with some experts now advocating the early use of interferon in low-risk patients, although more mature data is needed before practice guidelines change. We evaluate the literature to inform clinical decision-making regarding these controversies, including most recent data that has challenged the "watchful waiting" paradigm. Our discussion provides guidance on common clinical scenarios seen in low-risk ET and PV patients, who face a myriad of complex management decisions in their care.

Parity-based assessment of anemia and iron deficiency in pregnant women

OBJECTIVE

This study aimed to separately evaluate the prevalence of anemia and iron deficiency in nulliparous and multiparous women.

MATERIALS AND METHODS

We retrospectively examined data of women who delivered in our clinic from January 2016 to December 2018. Inclusion criteria were delivery occurring at ≥36 weeks and singleton pregnancy. Pregnant women with severe medical disorders were excluded. We estimated complete blood count (CBC) and serum ferritin (SF) in the first trimester and only CBC in the late second trimester. Data of nulliparas and multiparas were analyzed separately. Statistically significance was set at p < 0.05.

RESULTS

Totally, 481 nulliparas and 603 and multiparas were enrolled. Mean hemoglobin values in the first trimester were 12.6 ± 1.0 and 12.4 ± 1.0 g/dl (p < 0.001), while median SF values were 42.7 (12.2, 108.2) and 27.7 (8.0, 72.6) ng/ml (p < 0.001) in nulliparas and multiparas, respectively. Hemoglobin in the late second trimester was 11.2 ± 0.9 and 10.7 ± 1.0 g/dl (p < 0.001) in nulliparas and multiparas, respectively. Low ferritin levels (SF < 12 ng/ml) were more frequently found in multiparas than in nulliparas (111/603 vs. 46/481, p < 0.001, Odds ratio [OR] = 2.13). Anemia in the first trimester (hemoglobin<11.0 g/dl) was found in 3.5% (17/481) and 8.8% (53/603) (p < 0.001; OR, 2.63), while that in late second trimester (hemoglobin<10.5) was observed in 21.0% (101/481) and 36.3% (219/603) (p < 0.001, OR = 2.15) nulliparas and multiparas, respectively. Non-anemic women (hemoglobin level ≥11.0) with low ferritin levels (SF < 12 ng/ml) in the first trimester showed higher rate of anemia development in the second trimester than those with both normal hemoglobin and ferritin levels, irrespective of parity (51.3% [19/37] vs. 16.2% [69/427], p < 0.001 in nulliparas and 76.9% [60/78] vs. 26.5% [125/472], p < 0.001 in multiparas].

CONCLUSION

Anemia and low SF levels occurred more commonly in multiparous than in nulliparas. Further, low SF was a risk factor for anemia development in later pregnancy.

Iron deficiency anaemia in pregnancy: A contemporary review

Iron deficiency anaemia is a global health problem, which particularly affects pregnant women. Iron deficiency anaemia during pregnancy is associated with increased maternal and perinatal morbidity and mortality. Maternal iron deficiency may also be associated with neurocognitive deficits in infants. Iron requirements increase during pregnancy and are influenced by hepcidin, the master regulator of iron homeostasis. The enduring global burden of maternal anaemia suggests that currently employed iron supplementation strategies are suboptimal. Recent developments in our understanding of systemic and placental iron homeostasis may improve therapeutic effectiveness by altering the dose and frequency of oral iron. Intravenous iron appears to be a safe treatment to correct maternal anaemia rapidly but research on patient-centred outcomes and cost-effectiveness is needed. Future trials should be adequately powered to assess outcomes relevant to pregnant women.

Intravenous Iron Treatment in the Prevention of Iron Deficiency and Anaemia After Roux-en-Y Gastric Bypass

Background

Iron absorption is disturbed after Roux-en-Y gastric bypass (RYGB) and iron deficiency with or without anaemia affects almost half of all patients. Intravenous iron is an option when per oral iron is insufficient or not tolerated. This study explores whether routinely offering intravenous iron treatment when iron stores are empty can prevent anaemia and iron deficiency after RYGB.

Methods

This is a study of prospectively registered data on clinical information, haematological tests and intravenous iron treatment from 644 RYGB patients who underwent surgery between 2004 and 2013, postoperatively followed more than 5 years. Intravenous iron treatment was offered to patients with ferritin ≤ 15 μg/L.

Results

Clinical information was available for all patients at baseline and for 553/644 patients at 5 years; laboratory results were available for 540/644 patients at baseline and 411/644 patients after 5 years. The mean age was 39.8 (± 9.7) years. Overall, 187/483 (38.7%) women and 9/161 (5.6%) men were given intravenous iron treatment in the observation period. From baseline to 5 years, mean haemoglobin decreased by 0.3 g/dL in both men and women. Anaemia occurred in 18/311 (5.8%) women and 9/100 (9%) men at 5 years. Depleted iron stores (ferritin ≤ 15 μg/L) were seen among 44/323(13.6%) women and 3/102 (2.9%) men, and low iron stores (ferritin 16–50 μg/L) occurred in 144/326 (44.6%) women and 38/102 (37.3%) men 5 years after RYGB.

Conclusion

By routinely offering intravenous iron treatment to patients with depleted iron stores after RYGB, haemoglobin levels were preserved. Half of the patients experienced low or depleted iron stores at 5 years.

The effect of iron deficiency and anaemia on women's health

Iron deficiency and anaemia are global health problems and major causes of morbidity in women. Current definitions of anaemia in women are historic and have been challenged by recent data from observational studies. Menstrual loss, abnormal uterine bleeding and pregnancy put women at risk of developing iron deficiency which can result in severe fatigue, reduced exercise capacity and poor work performance. Iron deficiency and anaemia during pregnancy are associated with adverse maternal and fetal outcomes, including neurocognitive deficits in children born to iron-deficient mothers. Both iron deficiency and anaemia are common in women undergoing surgery but their association with poor outcomes remains uncertain. The enduring burden of iron deficiency and anaemia in women suggests that current strategies for recognition, prevention and treatment are limited in their utility. Improvements in our understanding of iron homeostasis and the development of new iron preparations, which are better absorbed with fewer side-effects, may improve therapeutic effectiveness of oral iron. Intravenous iron is efficacious for correcting anaemia rapidly but high-quality data on patient-centred outcomes and cost-effectiveness are currently lacking. Many recommendations for the treatment of iron deficiency and anaemia in national guidelines are not supported by high-quality evidence. There is a need for robust epidemiological data and well-designed clinical trials. The latter will require collaborative working between researchers and patients to design studies in ways that incorporate patients' perspectives on the research process and target outcomes that matter to them.

Zinc Protoporphyrin Is a Reliable Marker of Functional Iron Deficiency in Patients with Inflammatory Bowel Disease

Iron deficiency (ID) is a common manifestation of inflammatory bowel disease (IBD), arising primarily due to chronic inflammation and/or blood loss. There is no gold standard for ID diagnosis, which is often complicated by concomitant inflammation. Zinc protoporphyrin (ZnPP) correlates with parameters of iron homeostasis and has been identified as a promising marker for ID, irrespective of inflammation. We investigated the diagnostic performance of ZnPP in ID, iron deficiency anemia, anemia of chronic disease and mixed anemia in a cross-sectional study in 130 patients with IBD. Different parameters were compared by receiver operator characteristic (ROC) analysis as detectors of iron-restricted erythropoiesis (IRE). IRE was detected in 91 patients (70.0%); fifty-nine (64.8%) had absolute ID and 23 (25.4%) functional ID. When inflammation was present, ZnPP was a more reliable sole biomarker of IRE than MCV, transferrin saturation (TSAT) or ferritin (AUC; 0.855 vs. 0.763, 0.834% and 0.772, respectively). The specificity of TSAT was significantly lower than ZnPP when inflammation was present (38% vs. 71%, respectively). We conclude that ZnPP is a reliable biomarker of functional ID in patients with IBD and more dependable than ferritin or TSAT, which are influenced by chronic inflammation. We propose that ZnPP may also have utility in patients with other chronic diseases.

Key Nutritional Considerations for Youth Winter Sports Athletes to Optimize Growth, Maturation and Sporting Development

Despite a wealth of sport nutrition guidelines for adult athletes, there are currently no nutrition guidelines for youth winter sports athletes. Whilst it may be pragmatic to apply nutrition guidelines for adult athletes to youth winter sports athletes, it is inappropriate. Due to a paucity of research on youth athletes, it is impossible to provide evidence-based guidelines for this population, so careful extrapolation from the theoretical and practical considerations that apply to other athletic groups is necessary. Youth winter sport athletes undergo rapid biological growth and maturation which influences their nutritional requirements. A varied and balanced diet that ensures sufficient energy availability for optimal growth and maturation as well as sporting performance is the cornerstone of youth athlete nutrition and should also allow for youth athletes to meet their micronutrient requirements. In some cases, micronutrient status (e.g., vitamin D and iron) should be monitored and optimized if appropriate by a medical professional. Dietary supplement use is prevalent amongst youth athletes, however is often unnecessary. Education of youth athletes, their parents and coaches on best nutritional practices as well as the risks associated with dietary supplements is vital for their long-term athletic development. Further research in youth winter sports athletes across different stages of growth and maturation competing in a variety of sports is urgently required in order to inform nutritional guidelines for this population.

Iron Deficiency and Anemia 10 Years After Roux-en-Y Gastric Bypass for Severe Obesity

Iron deficiency with or without anemia is a well-known long-term complication after Roux-en-Y, gastric bypass (RYGB) as the procedure alters the gastrointestinal absorption of iron. Iron is essential for hemoglobin synthesis and a number of cellular processes in muscles, neurons, and other organs. Ferritin is the best marker of iron status, and in a patient without inflammation, iron deficiency occurs when ferritin levels are below 15 µg/L, while iron insufficiency occurs when ferritin levels are below 50 µg/L. Lifelong regular blood tests are recommended after RYGB, but the clinical relevance of iron deficiency and iron insufficiency might be misjudged as long as the hemoglobin levels are normal. The aim of this study was to explore the frequency of iron deficiency and iron deficiency anemia one decade or more after RYGB, the use of per oral iron supplements, and the frequency of intravenous iron treatment. Nine hundred and thirty patients who underwent RYGB for severe obesity at three public hospitals in Norway in the period 2003-2009 were invited to a follow-up visit 10-15 years later. Results from blood tests and survey data on the use of oral iron supplements and intravenous iron treatment were analyzed. Ferritin and hemoglobin levels more than 10 years after RYGB were available on 530 patients [423 (79.8%) women]. Median (IQR) ferritin was 33 (16-63) µg/L, and mean (SD) hemoglobin was 13.4 (1.3) g/dl. Iron deficiency (ferritin ≤ 15 µg/L) was seen in 125 (23.6%) patients; in addition, iron insufficiency (ferritin 16-50 µg/L) occurred in 233 (44%) patients. Mean (SD) hemoglobin levels were 12.5 (1.4) g/dl in patients with iron deficiency, 13.5 (1.2) g/dl in patients with iron insufficiency, 13.8 (1.3) g/dl in the 111 (21%) patients with ferritin 51-100 µg/L, and 13.8 (1.2) g/dl in the 55 (10%) patients with ferritin >100 µg/L. Two hundred and seventy-five (56%) patients reported taking oral iron supplements, and 138 (27.5%) had received intravenous iron treatment after the RYGB procedure. Iron deficiency or iron insufficiency occurred in two-thirds of the patients 10 years after RYGB, although more than half of them reported taking oral iron supplements.

Iron deficiency does not impair the outcome after elective coronary artery bypass and aortic valve procedures

BACKGROUND AND AIM OF THE STUDY: Iron deficiency (ID), a common malnutrition, has been linked to impaired prognosis in patients with congestive heart failure. It remains unclear whether ID also affects the outcome after elective cardiac surgery.

METHODS

A total of 378 consecutive patients undergoing either coronary artery bypass grafting (CABG) or surgical aortic valve replacement (SAVR) were prospectively enrolled, and blood samples were taken before surgery for analysis of iron metabolism. Incidence of major adverse cardiovascular and cerebrovascular events (MACCE) was defined as the primary endpoint of the study.

RESULTS

ID (ferritin < 100 ng/ml or ferritin = 100-299 ng/ml and transferrin saturation < 20%) was common in cardiac surgery patients (ID, n = 265, 70%) and related to significant decreased preoperative hemoglobin values (ID: 13.6 ± 1.6 g/dl, Non-ID: 14.3 ± 1.5 g/dl, p < 0.01). We did not observe any differences in the postoperative outcome of the two groups. The incidence of MACCE was 4.9% in patients with ID and 8.8% in Non-ID (p = 0.16). In-hospital mortality (ID: 1.9%, Non-ID: 4.4%, p = 0.17) and stroke (ID: 1.1%, Non-ID: 1.8%, p = 0.64) were also not altered by ID. In addition, intensive care unit and hospital stay, perioperative blood transfusions as well as perioperative morbidities, such as acute kidney injury, low cardiac output syndrome, major bleeding complication, and sternal wound infections were comparable in patients with and without ID.

CONCLUSIONS

The majority of patients undergoing elective CABG or SAVR suffer from ID; however, we found no significant differences in regard to MACCE and postoperative morbidity between ID and non-ID patients.

Ferritin readings in young adult, female university student recreational runners

BACKGROUND

Elite female athletes have shown vulnerability to various degrees of iron deficiency. Less is known about recreational fitness exercisers. A study was done to examine plasma ferritin, an assessor of iron status, in young adult, university student fitness runners.

METHODS

The present study examined serum ferritin concentrations, an indicator of iron status, in 39 female university students (age 18-25) who ran for fitness, but ran less than competition runners. Selected subjects all reported themselves as not anemic.

RESULTS

Mean + SD for 3 mile run time was 26.25 + 3.0 min. The mean ferritin reading was low: 12.4 + 12.3 ng/mL (+ SD). Out of the 39 women, 29 had readings that fell below 15 ng/mL, which some consider the cutoff for iron deficiency. In addition, all but 2 subjects had values below 35, which has been proposed as Stage 1 iron deficiency for athletes. Ferritin levels did not correlate with 3 mile run times (Pearson correlation coefficient, P > 0.05). A 1 mo intervention with 3 minerals that included iron (36 mg/day) significantly raised ferritin values when the iron was bisglycinate (p < 0.05), but not when it was ferrous sulfate (p > 0.05).

CONCLUSION

In this study, a degree of iron deficiency was seen in most of a group of female fitness runners (each of whom had self reported as not being anemic).

Can diet-induced weight loss improve iron homoeostasis in patients with obesity: A systematic review and meta-analysis

Despite the increasing worldwide prevalence of obesity and iron deficiency (ID), there are still no guidelines on how to treat and manage obesity-related ID. The aim of this systematic review and meta-analysis was to investigate whether weight loss can re-establish iron homoeostasis among subjects with unhealthy weight (overweight [OW] or obesity). PubMed, Medline, Embase, Web of Science, and the Cochrane Library were systemically searched for studies that compared the iron status before and after a weight-loss intervention. A random-effects model was used to calculate the pooled and subgroup weighted mean differences (WMDs) of iron biomarkers. In total, 879 subjects were pooled across 14 studies. Improved haemoglobin was found in longitudinal studies (WMD = 2.50 g/dl, 95% confidence interval [CI]: 0.88, 4.12 g/dl, I² = 14%) but not in randomized controlled trials or after being stratified by dietary programmes. Significantly increased transferrin saturation was observed in pooled (WMD = 1.68%, 95% CI: 0.97%, 2.39%, I² = 44%) and subgroup analyses. A meta-regression showed that changes in the iron status were positively correlated with changes in the body mass index (BMI) and the intervention duration but negatively correlated with the baseline body weight/BMI, age, gender and a standard hypocaloric diet. Our data suggested that in spite of energy restrictions, weight loss may help re-establish iron homoeostasis in people who are OW or obese.

Iron deficiency is a common disorder in general population and independently predicts all-cause mortality: results from the Gutenberg Health Study

BACKGROUND

Iron deficiency is now accepted as an independent entity beyond anemia. Recently, a new functional definition of iron deficiency was proposed and proved strong efficacy in randomized cardiovascular clinical trials of intravenous iron supplementation. Here, we characterize the impact of iron deficiency on all-cause mortality in the non-anemic general population based on two distinct definitions.

METHODS

The Gutenberg Health Study is a population-based, prospective, single-center cohort study. The 5000 individuals between 35 and 74 years underwent baseline and a planned follow-up visit at year 5. Tested definitions of iron deficiency were (1) functional iron deficiency-ferritin levels below 100 µg/l, or ferritin levels between 100 and 299 µg/l and transferrin saturation below 20%, and (2) absolute iron deficiency-ferritin below 30 µg/l.

RESULTS

At baseline, a total of 54.5% of participants showed functional iron deficiency at a mean hemoglobin of 14.3 g/dl; while, the rate of absolute iron deficiency was 11.8%, at a mean hemoglobin level of 13.4 g/dl. At year 5, proportion of newly diagnosed subjects was 18.5% and 4.8%, respectively. Rate of all-cause mortality was 7.2% (n = 361); while, median follow-up was 10.1 years. After adjustment for hemoglobin and major cardiovascular risk factors, the hazard ratio with 95% confidence interval of the association of iron deficiency with mortality was 1.3 (1.0-1.6; p = 0.023) for the functional definition, and 1.9 (1.3-2.8; p = 0.002) for absolute iron deficiency.

CONCLUSIONS

Iron deficiency is very common in the apparently healthy general population and independently associated with all-cause mortality in the mid to long term.

Association of red blood cell size and physical fitness in a military male cohort: The CHIEF study

Anemia manifested as reduced red blood cell (RBC) amounts or hemoglobin levels has been associated with lower cardiorespiratory fitness. However, the relationship of smaller RBC with physical fitness was unknown. We included 2933 non-anemic military males (hemoglobin levels: 11.1-15.9 g/dL and mean corpuscular volume (MCV) <100 fL) in Taiwan during 2014. Aerobic fitness was assessed by time for a 3000-meter run, and anaerobic fitness was evaluated by numbers of sit-ups and push-ups, each performed within 2 minutes. Multiple linear and logistic regression models adjusting for age, service specialty, lipid profiles, and hemoglobin levels were used to determine the associations. Microcytosis and normocytosis were defined as MCV ≤ 70 fL (n = 190) and MCV > 70 fL (n = 2743), respectively. The linear regression shows that as compared with microcytosis, normocytosis was associated with more numbers of sit-ups performed within 2 minutes (β = 1.51, P-value = 0.02). The logistic regression also reveals that those males with microcytosis had higher probability as the worst 10% performers in the 2-minute push-up test (odds ratio: 1.91, 95% confidence intervals: 1.18-3.12). By contrast, there was no association of microcytosis with 3000-meter running time. Our study suggests that non-anemic microcytosis was associated with lower anaerobic fitness but not with aerobic fitness. Whether the causative factors for microcytosis such as iron deficiency status and thalassemia trait unavailable in the study might account for the relationship needs further investigations.

Anemia in Children With Inflammatory Bowel Disease: A Position Paper by the IBD Committee of the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition

Anemia is one of the most common extraintestinal manifestations of inflammatory bowel disease (IBD). It can be asymptomatic or associated with nonspecific symptoms, such as irritability, headaches, fatigue, dizziness, and anorexia. In IBD patients, the etiology of anemia is often multifactorial. Various causes include iron deficiency, anemia of inflammation and chronic disease, vitamin deficiencies, hemolysis, or myelosuppressive effect of drugs. Anemia and iron deficiency in these patients may be underestimated because of their insidious onset, lack of standardized screening practices, and possibly underappreciation that treatment of anemia is also required when treating IBD. Practitioners may hesitate to use oral preparations because of their intolerance whereas intravenous preparations are underutilized because of fear of adverse events, availability, and cost. Several publications in recent years have documented the safety and comparative efficacy of various intravenous preparations. This article reviews management of anemia in children with IBD, including diagnosis, etiopathogenesis, evaluation of a patient, protocol to screen and monitor patients for early detection and response to therapy, treatment including parenteral iron therapy, and newer approaches in management of anemia of chronic disease. This report has been compiled by a group of pediatric gastroenterologists serving on the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) IBD committee, in collaboration with a pediatric hematologist, pharmacist, and a registered dietician who specializes in pediatric IBD (IBD Anemia Working Group), after an extensive review of the current literature. The purpose of this review is to raise awareness of under-diagnosis of anemia in children with IBD and make recommendations for screening, testing, and treatment in this population.

Decreased Physical Working Capacity in Adolescents With Nonalcoholic Fatty Liver Disease Associates With Reduced Iron Availability

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is common and related to obesity and insulin resistance. Iron metabolism is impaired in obese individuals and iron deficiency has been associated with physical inactivity. We investigated whether iron bioavailability is reduced in patients with NAFLD and contributes to reduced cardiorespiratory fitness.

METHODS

We collected information on weight-adjusted, submaximal physical work capacity (PWC), ultrasound-determined hepatic steatosis, iron indices, and hematologic and metabolic parameters from 390 female and 458 male participants of the Raine Study-a longitudinal study of disease development in 2868 children in Western Australia. X² and linear regression analyses were used to compare characteristics of study participants according to NAFLD status at age 17 years.

RESULTS

Fourteen percent of the cohort had NAFLD. PWC was significantly reduced in adolescents with NAFLD compared to adolescents without NAFLD (reduction of 0.17 W/kg, P = .0003, adjusted for sex and body mass index [BMI]). Iron bioavailability (assessed by mean corpuscular volume [MCV], mean corpuscular haemoglobin [MCH], transferrin saturation, and serum levels of iron) was inversely correlated with BMI in adolescents with NAFLD (P ≤ .01 for all, adjusted for sex) but not in adolescents without NAFLD (P > .30). MCV and MCH correlated with PWC (MCV, P = .002 for female and P = .0003 male participants; MCH, P = .004 for female and P = .01 for male participants), irrespective of NAFLD status. Reduced PWC was associated with lower transferrin saturation in adolescents with NAFLD (reduction of 0.012 W/kg per unit decrease in transferrin saturation, P = .007) but not in adolescents without NAFLD (reduction of 0.001 W/kg, P = .40), adjusted for sex. This association was independent of MCV or MCH.

CONCLUSIONS

In a well-defined cohort of adolescents, we found NAFLD to be associated with decreased cardiorespiratory fitness, independent of BMI. The relationship between transferrin saturation and PWC in adolescents with NAFLD indicates that functional iron deficiency might contribute to reductions in cardiorespiratory fitness.

The Effect of Parenteral or Oral Iron Supplementation on Fatigue, Sleep, Quality of Life and Restless Legs Syndrome in Iron-Deficient Blood Donors: A Secondary Analysis of the IronWoMan RCT

Background: Besides anemia, iron deficiency may cause more subtle symptoms, including the restless legs syndrome (RLS), the chronic fatigue syndrome (CFS) or sleeping disorders. Objective: The aim of this pre-planned secondary analysis of the IronWoMan randomized controlled trial (RCT) was to compare the frequency and severity of symptoms associated with iron deficiency before and after (intravenous or oral) iron supplementation in iron deficient blood donors. Methods/Design: Prospective, randomized, controlled, single-centre trial. (ClinicalTrials.gov: NCT01787526). Setting: Tertiary care center in Graz, Austria. Participants: 176 (138 female and 38 male) whole-blood and platelet apheresis donors aged ≥ 18 and ≤ 65 years with iron deficiency (ferritin ≤ 30ng/mL at the time of blood donation). Interventions: Intravenous iron (1 g ferric carboxymaltose, n = 86) or oral iron supplementation (10 g iron fumarate, 100 capsules, n = 90). Measurements: Clinical symptoms were evaluated by a survey before iron therapy (visit 0, V0) and after 8–12 weeks (visit 1, V1), including questions about symptoms of restless legs syndrome (RLS), chronic fatigue syndrome (CFS), sleeping disorders, quality of life and symptoms like headaches, dyspnoea, dizziness, palpitations, pica and trophic changes in fingernails or hair. Results: We found a significant improvement in the severity of symptoms for RLS, fatigue and sleep quality (p < 0.001). Furthermore, a significant decrease in headaches, dyspnoea, dizziness and palpitations was reported (p < 0.05). There was no difference between the type of iron supplementation (intravenous versus oral) and clinical outcome data. Conclusion: Iron supplementation in iron-deficient blood donors may be an effective strategy to improve symptoms related to iron deficiency and the wellbeing of blood donors.

The prevalence and associated mortality of non-anaemic iron deficiency in older adults: a 14 years observational cohort study

Iron is central to multiple biological pathways, and treatment of non-anaemic absolute iron deficiency (NAID) is beneficial in certain conditions. However, it is unknown if NAID is associated with increased mortality in older adults. A nationally representative sample of 4451 older adults from the English Longitudinal Study of Ageing was used. NAID was defined as serum ferritin < 30 μg/l and haemoglobin ≥ 120 g/l (women) or ≥ 130 g/l (men). Cumulative mortality was estimated by Kaplan-Meier method. Unadjusted and adjusted hazard ratios (HRs) of mortality were calculated using Cox proportional hazards regression models. Baseline NAID prevalence was 8·8% (95% confidence interval [CI] 8·0-9·7%); 10·9% (95% CI 9·7-12·3%) for women and 6·35% for men (95% CI 5·3-7·5%). The HR for mortality for individuals with NAID compared with non-anaemic individuals without iron deficiency over the 14-year follow-up was 1·58 (95% CI 1·29-1·93). This association was independent of all identified demographic, health-related and biological covariates, and robust in multiple sensitivity analyses. In older adults in England, NAID is common and associated with an increased mortality rate compared to non-anaemic individuals with normal serum ferritin. The association is principally driven by an excess mortality in women.

Diagnosis and management of iron deficiency in children with or without anemia: consensus recommendations of the SPOG Pediatric Hematology Working Group

Iron deficiency is the most prevalent nutritional deficiency affecting children and adolescents worldwide. A consistent body of epidemiological data demonstrates an increased incidence of iron deficiency at three timepoints: in the neonatal period, in preschool children, and in adolescents, where it particularly affects females.Conclusion: This narrative review focuses on the most suggestive symptoms of iron deficiency in childhood, describes the diagnostic procedures in situations with or without anemia, and provides Swiss expert-based management recommendations for the pediatric context.What is Known:• Iron deficiency (ID) is one of the most common challenges faced by pediatricians.• Significant progress in the diagnosis and therapy of ID has been made over the last decade.What is New:• Our expert panel provides ID management recommendations based on the best available evidence.• They include strategies for ID diagnosis and therapy, both oral and intravenous.

Iron deficiency is a common disorder in general population and independently predicts all-cause mortality: results from the Gutenberg Health Study

Background

Iron deficiency is now accepted as an independent entity beyond anemia. Recently, a new functional definition of iron deficiency was proposed and proved strong efficacy in randomized cardiovascular clinical trials of intravenous iron supplementation. Here, we characterize the impact of iron deficiency on all-cause mortality in the non-anemic general population based on two distinct definitions.

Methods

The Gutenberg Health Study is a population-based, prospective, single-center cohort study. The 5000 individuals between 35 and 74 years underwent baseline and a planned follow-up visit at year 5. Tested definitions of iron deficiency were (1) functional iron deficiency—ferritin levels below 100 µg/l, or ferritin levels between 100 and 299 µg/l and transferrin saturation below 20%, and (2) absolute iron deficiency—ferritin below 30 µg/l.

Results

At baseline, a total of 54.5% of participants showed functional iron deficiency at a mean hemoglobin of 14.3 g/dl; while, the rate of absolute iron deficiency was 11.8%, at a mean hemoglobin level of 13.4 g/dl. At year 5, proportion of newly diagnosed subjects was 18.5% and 4.8%, respectively. Rate of all-cause mortality was 7.2% (n = 361); while, median follow-up was 10.1 years. After adjustment for hemoglobin and major cardiovascular risk factors, the hazard ratio with 95% confidence interval of the association of iron deficiency with mortality was 1.3 (1.0–1.6; p = 0.023) for the functional definition, and 1.9 (1.3–2.8; p = 0.002) for absolute iron deficiency.

Conclusions

Iron deficiency is very common in the apparently healthy general population and independently associated with all-cause mortality in the mid to long term.

Graphic abstract

Intravenous iron therapy for non-anaemic, iron-deficient adults

BACKGROUND

Iron deficiency is one of the most common nutritional deficiencies, and has a number of physiological manifestations. Early, or non-anaemic iron deficiency can result in fatigue and diminished exercise capacity. Oral iron preparations have a high incidence of intolerable side effects, and are ineffective in certain forms of iron deficiency. Consequently, intravenous iron preparations are increasingly used in the treatment of non-anaemic iron deficiency. The newer, more stable iron preparations in particular purport to have a lower incidence of side effects, and are now used across a range of different patient populations.

OBJECTIVES

To assess the effects of intravenous iron therapy in the treatment of adults with non-anaemic iron deficiency.

SEARCH METHODS

On 18 October 2019 we electronically searched CENTRAL, MEDLINE, Embase, two further databases and two trials registries 2019. We handsearched the references of full-text extracted studies, and contacted relevant study authors for additional data.

SELECTION CRITERIA

We included randomised controlled trials that compared any intravenous iron preparation to placebo in adults. We excluded other forms of comparison such as oral iron versus placebo, intramuscular iron versus placebo, or intravenous iron studies where other iron preparations were used as the comparator. We also excluded studies involving erythropoietin therapy or obstetric populations.

DATA COLLECTION AND ANALYSIS

Two review authors screened references for eligibility, extracted data and assessed risk of bias. We resolved differences in opinion through discussion and consensus, and where necessary, involved a third review author to adjudicate disputes. We contacted study authors to request additional data where appropriate. The primary outcome measures were haemoglobin concentration at the end of follow-up, and quality-of-life scores at end of follow-up. Secondary outcome measures were serum ferritin, peak oxygen consumption (as measured by cardiopulmonary exercise testing), adverse effects (graded as mild to moderate and severe) and bacterial infection. We pooled data for continuous outcomes, which we then reported as mean differences (MDs) with 95% confidence intervals (CIs). We reported quality-of-life metrics as standardised mean difference (SMD), and then converted them back into a more familiar measure, the Piper Fatigue Scale. We analysed dichotomous outcomes as risk ratios (RRs). Given an expected degree of heterogeneity, we used a random-effects model for all outcomes. We performed the analysis with the software package Review Manager 5.

MAIN RESULTS

This review includes 11 studies with 1074 participants. Outcome metrics for which data were available (haemoglobin concentration, quality-of-life scores, serum ferritin, peak oxygen consumption and mild to moderate adverse effects) were similar across the included studies. The incidence of severe adverse events across all studies was zero. None of the studies measured bacterial infection as a specific outcome metric. Substantial heterogeneity influenced the results of the meta-analysis, arising from differing patient populations, definitions of iron deficiency, iron preparations and dosing regimens, and time to end of follow-up. Consequently, many outcomes are reported with small group sizes and wide confidence intervals, with a subsequent downgrading in the quality of evidence. The level of bias in many included studies was high, further reducing confidence in the robustness of the results. We found that intravenous iron therapy may lead to a small increase in haemoglobin concentration of limited clinical significance compared to placebo (MD 3.04 g/L, 95% CI 0.65 to 5.42; I2 = 42%; 8 studies, 548 participants; low-quality evidence). Quality-of-life scores (Piper Fatigue Scale MD 0.73, 95% CI 0.29 to 1.18; I2 = 0%; studies = 3) and peak oxygen consumption (MD 2.77 mL/kg/min, 95% CI -0.89 to 6.43; I2 = 36%; 2 studies, 32 participants) were associated with very low-quality evidence, and we remain uncertain about the role of intravenous iron for these metrics. We were unable to present pooled estimates for the outcomes of serum ferritin at the end of follow-up or mild to moderate adverse effects due to extreme statistical heterogeneity. Ultimately, despite the results of the meta-analysis, the low- or very low-quality evidence for all outcomes precludes any meaningful interpretation of results beyond suggesting that further research is needed. We performed a Trial Sequential Analysis for all major outcomes, none of which could be said to have reached a necessary effect size.

AUTHORS' CONCLUSIONS

Current evidence is insufficient to show benefit of intravenous iron preparations for the treatment of non-anaemic iron deficiency across a variety of patient populations, beyond stating that it may result in a small, clinically insignificant increase in haemoglobin concentration. However, the certainty for even this outcome remains limited. Robust data for the effectiveness of intravenous iron for non-anaemic iron deficiency is still lacking, and larger studies are required to assess the effect of this therapy on laboratory, patient-centric, and adverse-effect outcomes.