Tissue iron deficiency without anemia impairs adaptation in endurance capacity after aerobic training in previously untrained women

Disordered iron homeostasis in chronic heart failure: prevalence, predictors, and relation to anemia, exercise capacity, and survival

OBJECTIVES

The aim of this study was to comprehensively delineate iron metabolism and its implications in patients with chronic heart failure (CHF).

BACKGROUND

Iron deficiency is an emerging therapeutic target in CHF.

METHODS

Iron and clinical indexes were quantified in 157 patients with CHF.

RESULTS

Several observations were made. First, iron homeostasis was deranged in anemic and nonanemic subjects and characterized by diminished circulating (transferrin saturation) and functional (mean cell hemoglobin concentration) iron status in the face of seemingly adequate stores (ferritin). Second, while iron overload and elevated iron stores were rare (1%), iron deficiency (transferrin saturation <20%) was evident in 43% of patients. Third, disordered iron homeostasis related closely to worsening inflammation and disease severity and strongly predicted lower hemoglobin levels independently of age, sex, erythrocyte sedimentation rate, New York Heart Association (NYHA) functional class, and creatinine. Fourth, the etiologies of anemia varied with disease severity, with an iron-deficient substrate (anemia of chronic disease and/or iron-deficiency anemia) evident in 16%, 72%, and 100% of anemic NYHA functional class I or II, III, and IV patients, respectively. Although anemia of chronic disease was more prevalent than iron-deficiency anemia, both conditions coexisted in 17% of subjects. Fifth, iron deficiency was associated with lower peak oxygen consumption and higher ratios of ventilation to carbon dioxide production and identified those at enhanced risk for death (hazard ratio: 3.38; 95% confidence interval: 1.48 to 7.72; p = 0.004) independently of hemoglobin. Nonanemic iron-deficient patients had a 2-fold greater risk for death than anemic iron-replete subjects.

CONCLUSIONS

Disordered iron homeostasis in patients with CHF relates to impaired exercise capacity and survival and appears prognostically more ominous than anemia.

FERGIcor, a randomized controlled trial on ferric carboxymaltose for iron deficiency anemia in inflammatory bowel disease

BACKGROUND & AIMS

Iron deficiency anemia (IDA) is common in chronic diseases and intravenous iron is an effective and recommended treatment. However, dose calculations and inconvenient administration may affect compliance and efficacy. We compared the efficacy and safety of a novel fixed-dose ferric carboxymaltose regimen (FCM) with individually calculated iron sucrose (IS) doses in patients with inflammatory bowel disease (IBD) and IDA.

METHODS

This randomized, controlled, open-label, multicenter study included 485 patients with IDA (ferritin <100 μg/L, hemoglobin [Hb] 7-12 g/dL [female] or 7-13 g/dL [male]) and mild-to-moderate or quiescent IBD at 88 hospitals and clinics in 14 countries. Patients received either FCM in a maximum of 3 infusions of 1000 or 500 mg iron, or Ganzoni-calculated IS dosages in up to 11 infusions of 200 mg iron. Primary end point was Hb response (Hb increase ≥ 2 g/dL); secondary end points included anemia resolution and iron status normalization by week 12.

RESULTS

The results of 240 FCM-treated and 235 IS-treated patients were analyzed. More patients with FCM than IS achieved Hb response (150 [65.8%] vs 118 [53.6%]; 12.2% difference, P = .004) or Hb normalization (166 [72.8%] vs 136 [61.8%]; 11.0% difference, P = .015). Both treatments improved quality of life scores by week 12. Study drugs were well tolerated and drug-related adverse events were in line with drug-specific clinical experience. Deviations from scheduled total iron dosages were more frequent in the IS group.

CONCLUSIONS

The simpler FCM-based dosing regimen showed better efficacy and compliance, as well as a good safety profile, compared with the Ganzoni-calculated IS dose regimen.

Treatment of anemia in heart failure: potential risks and benefits of intravenous iron therapy in cardiovascular disease

Iron-deficiency anemia is common in patients with heart failure (HF), but the optimum diagnostic tests to detect iron deficiency and the treatment options to replete iron have not been fully characterized. Recent studies in patients with HF indicate that intravenous iron can rapidly replenish iron stores in patients having iron-deficiency anemia, with resultant increased hemoglobin levels and improved functional capacity. Preliminary data from a subgroup analysis also suggest that supplemental intravenous iron therapy can improve functional capacity even in those subjects without anemia. The mechanisms responsible for this observation are not fully characterized, but may be related to beneficial effects of iron supplementation on mitochondrial respiration in skeletal muscle. The long-term safety of using intravenous iron supplementation in HF populations is not known. Iron is a known pro-oxidant factor that can inhibit nitric oxide signaling and irreversibly injury cells. Increased iron stores are associated with vascular endothelial dysfunction and increased risk of coronary heart disease events. Additional clinical trials are needed to more fully characterize the therapeutic potential and safety of intravenous iron in HF patients.

Aspectos gerais da deficiência de ferro no esporte, suas implicações no desempenho e importância do diagnóstico precoce

A ingestão inadequada de ferro pode trazer consequências deletérias ao desempenho atlético. Os aspectos negativos provenientes da deficiência orgânica de ferro estão diretamente relacionados com os níveis de depleção desse mineral, que, em sua última instância, tem como principal agravo o desenvolvimento da anemia ferropriva. O presente artigo esclarece que, além da omissão férrica dietética, existem vários fatores agregados que não estão vinculados apenas à dieta, mas que, no conjunto, podem interferir sobre o balanço negativo do ferro, principalmente em atletas. Dentre os fatores etiológicos associados à prática esportiva, os mais evidentes são as hemorragias gastrintestinais, as hemólises por impacto e por radicais livres e as perdas férricas através da transpiração. Nota-se a suma importância do controle da ingestão de ferro e da manutenção de uma vigilância para a detecção precoce da deficiência desse mineral, evitando alteração na produção normal de hemoglobina e de outros compostos essenciais, o que pode causar redução considerável no desempenho do indivíduo, principalmente aeróbico. Embora seja crucial o papel da suplementação no restabelecimento do indivíduo com deficiência de ferro, a automedicação é contraindicada, devido às consequências negativas associadas às altas doses desse mineral. A abordagem desse tema é de extrema relevância para o meio esportivo, contendo informações sobre a anemia esportiva e o diagnóstico da deficiência de ferro, em uma revisão que visa o esclarecimento dos principais fatores etiológicos envolvidos.

Anemia and iron deficiency in heart failure: mechanisms and therapeutic approaches

Anemia and iron deficiency are common in patients with heart failure (HF), and are associated with worse symptoms and adverse outcomes in this population. Although the two can occur together, anemia in HF is often not caused by iron deficiency, and iron deficiency can be present without causing anemia. Erythropoiesis-stimulating agents have been investigated extensively in the past few years and might be of benefit in patients with HF and anemia. However, concerns have arisen regarding the safety of erythropoiesis-stimulating agents in patients with chronic kidney disease and so the results of a large mortality trial are eagerly awaited to provide information on safety in patients with HF. Iron supplementation or replacement is a much older treatment option for patients with HF and anemia, but questions about the safety of intravenous iron, and absorption problems with oral formulations have prevented its widespread use to date. In the past few years, however, new data on the importance of iron deficiency in HF have become available, and a number of studies with intravenous iron have shown promising results. Therefore, this treatment approach is likely to become an attractive option for patients with HF and iron deficiency, both with and without anemia.

A comparison of self-reported and record-linked blood donation history in an Australian cohort

BACKGROUND

Questionnaire-based studies investigating blood donation history rely on the accurate recall of information from participants for results to be valid. This study aimed to retrieve electronic records from a national blood donation service and link them to self-reported history of donation to assess agreement between the two sources.

STUDY DESIGN AND METHODS

Between 2004 and 2006, a sample of participants of northern European descent was selected from the Melbourne Collaborative Cohort Study (n = 31,192) to participate in the "HealthIron" study (n = 1438). A total of 1052 participants completed questionnaires that included questions about blood donation history. In 2009, consenting participants' records were linked to the Australian Red Cross Blood Service (ARCBS) to provide information on blood donations made between 1980 and follow-up (2004-2006). Those who commenced blood donation before 1980 were excluded.

RESULTS

A total of 718 participants were available for analysis. Of these, 394 (55%) provided signed consent, including 182 (82%) of the 227 participants who self-reported ever donating blood. The two data sources were concordant for 331 (87%) of participants, with a κ statistic of 0.74 (SE, 0.05) indicating a high level of agreement. Participants tended to overstate by a factor of 2.0 (95% confidence interval, 1.7-2.2) the number of donations they had made when compared with ARCBS records.

CONCLUSION

Participants in studies assessing self-reported blood donation history are likely to correctly indicate whether or not they have ever donated blood. Quantitative estimates are potentially inaccurate and could benefit from validating a sample of records to quantify the bias.

Iron Nutrition and the Female Athlete: Countermeasures for the Prevention of Poor Iron Status

Iron is a trace element found in the diet and is essential for cognition and energy metabolism. Poor iron status is a concern for female athletes, who might not consume adequate levels of dietary iron and could experience elevated iron loss from physiologic processes associated with physical activity. Physical performance and cognitive decrements have been demonstrated in female athletes with iron deficiency anemia; both improve with increased iron intake. Two approaches for increasing iron intake in female athletes are the consumption of iron supplements and increasing dietary intake of foods high in iron to include iron-fortified foods. Both of these approaches have advantages and disadvantages that should be considered when treating female athletes with poor iron status.

A pilot iron substitution programme in female blood donors with iron deficiency without anaemia

BACKGROUND AND OBJECTIVES

Blood donation can contribute to iron deficiency. The possibly resulting anaemia importantly affects donor return rate. The determination of serum ferritin levels revealed iron deficiency in many non-anaemic premenopausal female blood donors at our Institution. We started an iron substitution programme targeting this donor group to prevent anaemia and enhance donor retain.

MATERIALS AND METHODS

Women aged≤50 with haemoglobin levels adequate for donation and serum ferritin≤10 ng/ml were offered iron supplementation. Substitution lasted 16 weeks and the donation interval was extended. History collection including iron deficiency-related symptoms, whole blood count and serum ferritin determination was performed at baseline and after 2 and 6 months. Data were recorded prospectively and compared with those of 108 female controls with iron deficiency not receiving iron substitution (retrospective data).

RESULTS

Of the 116 participating subjects, 60% completed the programme. Significant results were serum ferritin increase (from a mean value of 7.12 to 25.2 ng/ml), resolution of prostration, fatigue, sleep disturbances, tension in the neck, hair loss and nail breakage. No case of anaemia occurred. Sixty per cent of the women completed the programme and donated blood again.

CONCLUSIONS

Targeted iron substitution prevents the development of anaemia and enhances donation return in premenopausal female blood donors with iron deficiency.

Diagnosis and management of iron deficiency anemia in patients with IBD

Anemia is the most prevalent extraintestinal complication of IBD. It can affect quality of life and ability to work, and can also increase the hospitalization rate in patients with IBD. Although the causes of anemia in IBD are multifactorial, iron deficiency anemia (IDA) is the most common. Assessment of the iron status of patients who have a condition associated with inflammation, such as IBD, by using common biochemical values is insufficient. However, new indices of iron metabolism (for instance ferritin:transferrin receptor ratio, reticulocyte hemoglobin content or percentage of hypochromic red blood cells) may help to improve the assessment of iron status in patients with IBD. The treatment of IDA traditionally involves oral iron supplementation. However, because of extensive gastrointestinal adverse effects, and data showing that the use of oral iron in IBD may be associated with disease exacerbation, current guidelines suggest that iron supplementation in IBD should be administered intravenously. This Review provides an overview of iron homeostasis in health before discussing diagnostic and therapeutic strategies for IDA in patients with IBD.

Paraoxonase activity in athletes with depleted iron stores and iron-deficient erythropoiesis

OBJECTIVE

The aim of this study was to evaluate how conditions that precede anaemia (iron store depletion and iron-deficient erythropoiesis) affect human serum paraoxonase PON1 activity.

DESIGN AND METHODS

Based on haemoglobin, transferrin saturation and serum ferritin values 119 athletes were divided into three groups: with iron depletion, with deficient erythropoiesis and controls. The following parameters were measured: paraoxonase activity towards paraoxon (POase) and diazoxon (DZOase), lipid hydroperoxides (LOOH), the pro-oxidant-antioxidant balance (PAB), red blood cells (RBC) and lipid status.

RESULTS

Significant differences were found between athletes with different stages of iron deficiency and controls with respect to PON 1 activity and oxidative stress status parameters (Wilks' Lambda=0.712, F=5.241, p<0.001, η(2)=0.156). There was no significant difference between the PON1 192 Q and R polymorphism distribution in the two groups of athletes with different stages of iron deficiency and controls (χ(2)=1.086; p=0.896). PON1 activity was positively correlated with RBCs, haemoglobin, transferrin saturation (p<0.001) and ferritin (p=0.037) and negatively correlated with LOOH (p=0.044) in all three study groups.

CONCLUSIONS

Deficient erythropoiesis in athletes contributes to impaired PON1 activity. In contrast, iron depletion, regardless of increased oxidative stress, does not affect PON1 activity.

Demographic correlates of low hemoglobin deferral among prospective whole blood donors

BACKGROUND

Approximately 10% of attempted blood donations are not allowed because of low hemoglobin (Hb) deferral.

STUDY DESIGN AND METHODS

Low Hb deferrals were tracked in more 715,000 whole blood donors at six blood centers across the United States. A multivariable logistic regression model was developed to comprehensively assess demographic correlates for low Hb deferral.

RESULTS

Demographic factors significantly associated with low Hb deferral include female sex (11 times greater odds than males), increasing age in men (men over 80 have 29 times greater odds than men under 20), African American race (2-2.5 times greater odds than Caucasians), Hispanic ethnicity in women (1.29 times greater odds than Caucasian women), and weight in men (men under 124 pounds have 2.5 times greater odds than men over 200 pounds). Interestingly, increasing donation frequency is associated with decreased odds for low Hb deferral (women with one donation in the previous 12 months have two times greater odds than those with six donations).

CONCLUSIONS

Low Hb deferral is associated with female sex, older age, African American race/ethnicity, and lower body weight in men. An inverse association with donation frequency suggests a selection bias in favor of donors able to give more frequently. These data provide useful information that can be utilized to manage blood donors to limit low Hb deferrals and assist in policy decisions such as changing the Hb cutoff or permissible frequency of donation. They also generate hypotheses for new research of the causes of anemia in defined groups of donors.

Iron excess in recreational marathon runners

BACKGROUND/OBJECTIVES

Iron deficiency and anemia may impair athletic performance, and iron supplements are commonly consumed by athletes. However, iron overload should be avoided because of the possible long-term adverse health effects.

METHODS

We investigated the iron status of 170 male and female recreational runners participating in the Zürich marathon. Iron deficiency was defined either as a plasma ferritin (PF) concentration <15 microg/l (iron depletion) or as the ratio of the concentrations of transferrin receptor (sTfR) to PF (sTfR:log(PF) index) of > or =4.5 (functional iron deficiency).

RESULTS

After excluding subjects with elevated C-reactive protein concentrations, iron overload was defined as PF >200 microg/l. Iron depletion was found in only 2 out of 127 men (1.6% of the male study population) and in 12 out of 43 (28.0%) women. Functional iron deficiency was found in 5 (3.9%) and 11 (25.5%) male and female athletes, respectively. Body iron stores, calculated from the sTfR/PF ratio, were significantly higher (P<0.001) among male compared with female marathon runners. Median PF among males was 104 microg/l, and the upper limit of the PF distribution in males was 628 microg/l. Iron overload was found in 19 out of 127 (15.0%) men but only 2 out of 43 in women (4.7%). Gender (male sex), but not age, was a predictor of higher PF (P<0.001).

CONCLUSIONS

Iron depletion was present in 28% of female runners but in <2% of males, whereas one in six male runners had signs of iron overload. Although iron supplements are widely used by athletes in an effort to increase performance, our findings indicate excess body iron may be common in male recreational runners and suggest supplements should only be used if tests of iron status indicate deficiency.

The effect of gold kiwifruit consumed with an iron fortified breakfast cereal meal on iron status in women with low iron stores: a 16 week randomised controlled intervention study

Background

Dietary treatment is often recommended as the first line of treatment for women with mild iron deficiency. Although it is well established that ascorbic acid enhances iron absorption, it is less clear whether the consumption of ascorbic acid rich foods (such as kiwifruit) with meals fortified with iron improves iron status. The aim of this study is to investigate whether the consumption of ZESPRI^® GOLD kiwifruit (a fruit high in ascorbic acid and carotenoids) with an iron fortified breakfast cereal meal increases iron status in women with low iron stores.

Methods/Design

Eighty nine healthy women aged 18-44 years with low iron stores (serum ferritin (SF) ≤ 25 μg/L, haemoglobin (Hb) ≥ 115 g/L) living in Auckland, New Zealand were randomised to receive an iron fortified breakfast cereal (16 mg iron per serve) and either two ZESPRI^® GOLD kiwifruit or a banana (low ascorbic acid and carotenoid content) to eat at breakfast time every day for 16 weeks. Iron status (SF, Hb, C-reactive protein (CRP) and soluble transferrin receptor (sTfR)), ascorbic acid and carotenoid status were measured at baseline and after 16 weeks. Anthropometric measures, dietary intake, physical activity and blood loss were measured before and after the 16 week intervention.

Discussion

This randomised controlled intervention study will be the first study to investigate the effect of a dietary based intervention of an iron fortified breakfast cereal meal combined with an ascorbic acid and carotenoid rich fruit on improving iron status in women with low iron stores.

Trial registration

ACTRN12608000360314

Physical performance of migrant schoolchildren with marginal and severe iron deficiency in the suburbs of Beijing

OBJECTIVES

To investigate relationship between iron deficiency of different degrees and physical performance and habitual activity of migrant schoolchildren at the age of 11-14 years.

METHODS

Ninety one randomly selected schoolchildren were divided into three groups according to their iron status. Iron status including hemoglobin (Hb), serum ferritin (SF), serum iron (SI) and sTfR was determined. Physical performance tests included maximum oxygen consumption (VO2max) and maximum work time. Energy expenditure (EE) and daily physical activity were estimated by recording 24-h heart rate (HR). Dietary intake was assessed with frequency questionnaires, and physical activity level was estimated with frequency and physical activity questionnaires.

RESULTS

Severe iron deficiency (IDA) impaired the aerobic capacity and habitual physical activity. When fat-free mass (FFM) was considered, VO2max (VO2max/FFM) was significantly lower in the iron-marginal group than in the iron-adequate groups among girls (P = 0.02), but such a deference was not found among boys (P = 0.28). Aerobic activity and EE at leisure were significantly lower in the severe iron deficient group than in the marginal iron deficient and iron adequate groups. Net HR at leisure time was correlated with Hb, log SF, body weight, and FFM (P < 0.05).

CONCLUSION

The functional effect of iron deficiency on physical performance and habitual physical activity rely on the degree of current iron deficiency. Severe iron deficiency significantly impairs both aerobic capacity and habitual physical activity. Iron-marginal deficiency impairs VO2max/FFM in girls, rather than in boys.

Randomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and mood

BACKGROUND

Decrements in iron status have been reported in female soldiers during military training. Diminished iron status adversely affects physical and cognitive performance.

OBJECTIVE

We wanted to determine whether iron supplementation could prevent decrements in iron status and improve measures of physical performance and cognitive status in female soldiers during basic combat training (BCT).

DESIGN

In this 8-wk randomized, double-blind, placebo-controlled trial, soldier volunteers (n = 219) were provided with capsules containing either 100 mg ferrous sulfate or a placebo. Iron status indicator assays were performed pre- and post-BCT. Two-mile running time was assessed post-BCT; mood was assessed by using the Profile of Mood States questionnaire pre- and post-BCT.

RESULTS

The BCT course affected iron status: red blood cell distribution width and soluble transferrin receptor were elevated (P < 0.05), and serum ferritin was lowered (P < 0.05) post-BCT. Iron supplementation attenuated the decrement in iron status; group-by-time interactions (P < 0.01) were observed for serum ferritin and soluble transferrin receptor. Iron supplementation resulted in improved (P < 0.05) vigor scores on the Profile of Mood States post-BCT and in faster running time (P < 0.05) in volunteers reporting to BCT with iron deficiency anemia.

CONCLUSIONS

Iron status is affected by BCT, and iron supplementation attenuates the decrement in indicators of iron status in female soldiers. Furthermore, iron supplementation may prove to be beneficial for mood and physical performance during the training period. Future efforts should identify and treat female soldiers or athletes who begin training regimens with iron deficiency or iron deficiency anemia.

Nutrition for distance events

The goal of training is to prepare the distance athlete to perform at his or her best during major competitions. Whatever the event, nutrition plays a major role in the achievement of various factors that will see a runner or walker take the starting line in the best possible form. Everyday eating patterns must supply fuel and nutrients needed to optimize their performance during training sessions and to recover quickly afterwards. Carbohydrate and fluid intake before, during, and after a workout may help to reduce fatigue and enhance performance. Recovery eating should also consider issues for adaptation and the immune system that may involve intakes of protein and some micronutrients. Race preparation strategies should include preparation of adequate fuel stores, including carbohydrate loading for prolonged events such as the marathon or 50-km walk. Fluid and carbohydrate intake during races lasting an hour or more should also be considered. Sports foods and supplements of value to distance athletes include sports drinks and liquid meal supplements to allow nutrition goals to be achieved when normal foods are not practical. While caffeine is an ergogenic aid of possible value to distance athletes, most other supplements are of minimal benefit.

Iron deficiency and obesity: the contribution of inflammation and diminished iron absorption

Poor iron status affects billions of people worldwide. The prevalence of obesity continues to rise in both developed and developing nations. An association between iron status and obesity has been described in children and adults. The mechanism explaining this relationship remains unknown; however, findings from recent reports suggest that body mass index and inflammation predict iron absorption and affect the response to iron fortification. The relationship between inflammation and iron absorption may be mediated by hepcidin, although further studies will be required to confirm this potential physiological explanation for the increased prevalence of iron deficiency in the obese.

Relation of serum ferritin level to cardiovascular fitness among young men

Although iron overload is associated with fatigue and low ferritin is associated with decreased cardiovascular fitness (CVF), little research has focused on the relation of elevated ferritin with CVF in young adult men. An analysis of the National Health and Nutrition Examination Survey 1999-2002 was conducted to examine the relation between elevated ferritin and CVF in relatively healthy young adult men. Adult men aged 20 to 49 years (unweighted n = 1,030, weighted n = 28,514,823) who participated in a treadmill test for CVF were evaluated. Logistic regressions were computed for ferritin with CVF, adjusting for age, race or ethnicity, body mass index, anemia, smoking, exercise, blood donation, and C-reactive protein. Subjects with ferritin >300 ng/ml were less likely than those with normal ferritin to have high CVF (odds ratio [OR] 0.57, 95% confidence interval [CI] 0.32 to 0.99). When ferritin was split into categories, in a fully adjusted model with a reference group of ferritin at 16 to 100 ng/ml, except for ferritin >100 but <150 ng/ml (OR 0.84, 95% CI 0.65 to 1.08), higher ferritin was associated with a decreased likelihood of high CVF (>150 but <200 ng/ml: OR 0.55, 95% CI 0.40 to 0.77; >200 but <300 ng/ml: OR 0.49, 95% CI 0.33 to 0.72; >300 ng/ml: OR 0.40, 95% CI 0.23 to 0.70). The prevalence of ferritin >150 ng/ml was 45.5% in young adult men. In conclusion, elevated ferritin levels, even those much lower than what is normally considered to be elevated, were associated with a decreased likelihood of having high CVF in young adult men.

Anemia and chronic heart failure implications and treatment options

Anemia is a common comorbidity in patients with heart failure and is associated with worse long-term outcomes. Although the cause of anemia in heart failure is unclear, the weight of evidence suggests that renal dysfunction, along with neurohormonal and proinflammatory cytokine activation in heart failure, favors the development of anemia of chronic disease, with defective iron utilization, inappropriate erythropoietin production, and depressed bone marrow function. Similarly, the mechanisms by which anemia worsens heart failure outcomes are unknown but may be related to increased myocardial workload. If anemia is a mediator and not just a marker of poor outcomes, correcting anemia could become an important and novel therapeutic target to improve long-term outcomes in such patients. Indeed, several small-sized studies have shown the beneficial effects of empirically treating anemia in heart failure patients with recombinant erythropoietin and intravenous iron. However, the ideal threshold at which therapy should be initiated and the extent of correction considered safe and desirable in the individual patient with heart failure need to be known. These issues become more important because of increasing safety concerns that recombinant erythropoietin therapy for treating anemia may be associated with adverse cardiovascular outcomes in patients with chronic kidney disease and may worsen cancer in patients receiving chemotherapy to treat various types of cancer. Therefore, further prospectively designed studies are required to address some of these questions. Fortunately, 2 large mortality morbidity trials, TREAT (Trial to Reduce Cardiovascular Events with Aranesp Therapy) in patients with chronic kidney disease and RED-HF (Reduction of Events with Darbepoetin alfa in Heart Failure) in heart failure patients, are in progress and are likely to provide definitive answers.

Iron and anemia in human biology: a review of mechanisms

The biology of iron in relation to anemia is best understood by a review of the iron cycle, since the majority of iron for erythropoiesis is provided by iron recovered from senescent erythrocytes. In iron-deficiency anemia, storage iron declines until iron delivery to the bone marrow is insufficient for erythropoiesis. This can be monitored with clinical indicators, beginning with low plasma ferritin, followed by decreased plasma iron and transferrin saturation, and culminating in red blood cells with low-Hb content. When adequate dietary iron is provided, these markers show return to normal, indicating a response to the dietary supplement. Anemia of inflammation (also known as anemia of chronic disease, or ACD) follows a different course, because in this form of anemia storage iron is often abundant but not available for erythropoiesis. The diagnosis of ACD is more difficult than the diagnosis of iron-deficiency anemia, and often the first identified symptom is the failure to show a response to a dietary iron supplement. Confirmation of ACD is best obtained from elevated markers of inflammation. The treatment of ACD, which typically employs erythropoietin (EPO) supplements and intravenous iron (i.v.-iron), is empirical and often falls shorts of therapeutic goals. Dialysis patients show a complex pattern of anemia, which results from inadequate EPO production by the kidney, inflammation, changes in nutrition, and blood losses during treatment. EPO and i.v.-iron are the mainstays of treatment. Patients with heart failure can be anemic, with incidence as high as 50%. The causes are multifactorial; inflammation now appears to be the primary cause of this form of anemia, with contributions from increased plasma volume, effects of drug therapy, and other complications of heart disease. Discerning the mechanisms of anemia for the heart failure patient may aid rational therapy in each case.

Effect of intravenous iron sucrose on exercise tolerance in anemic and nonanemic patients with symptomatic chronic heart failure and iron deficiency FERRIC-HF: a randomized, controlled, observer-blinded trial

OBJECTIVES

We tested the hypothesis that intravenous iron improves exercise tolerance in anemic and nonanemic patients with symptomatic chronic heart failure (CHF) and iron deficiency.

BACKGROUND

Anemia is common in heart failure. Iron metabolism is disturbed, and administration of iron might improve both symptoms and exercise tolerance.

METHODS

We randomized 35 patients with CHF (age 64 +/- 13 years, peak oxygen consumption [pVO2] 14.0 +/- 2.7 ml/kg/min) to 16 weeks of intravenous iron (200 mg weekly until ferritin >500 ng/ml, 200 mg monthly thereafter) or no treatment in a 2:1 ratio. Ferritin was required to be <100 ng/ml or ferritin 100 to 300 ng/ml with transferrin saturation <20%. Patients were stratified according to hemoglobin levels (<12.5 g/dl [anemic group] vs. 12.5 to 14.5 g/dl [nonanemic group]). The observer-blinded primary end point was the change in absolute pVO2.

RESULTS

The difference (95% confidence interval [CI]) in the mean changes from baseline to end of study between the iron and control groups was 273 (151 to 396) ng/ml for ferritin (p < 0.0001), 0.1 (-0.8 to 0.9) g/dl for hemoglobin (p = 0.9), 96 (-12 to 205) ml/min for absolute pVO2 (p = 0.08), 2.2 (0.5 to 4.0) ml/kg/min for pVO2/kg (p = 0.01), 60 (-6 to 126) s for treadmill exercise duration (p = 0.08), -0.6 (-0.9 to -0.2) for New York Heart Association (NYHA) functional class (p = 0.007), and 1.7 (0.7 to 2.6) for patient global assessment (p = 0.002). In anemic patients (n = 18), the difference (95% CI) was 204 (31 to 378) ml/min for absolute pVO2 (p = 0.02), and 3.9 (1.1 to 6.8) ml/kg/min for pVO2/kg (p = 0.01). In nonanemic patients, NYHA functional class improved (p = 0.06). Adverse events were similar.

CONCLUSIONS

Intravenous iron loading improved exercise capacity and symptoms in patients with CHF and evidence of abnormal iron metabolism. Benefits were more evident in anemic patients. (Effect of Intravenous Ferrous Sucrose on Exercise Capacity in Chronic Heart Failure; http://www.clinicaltrials.gov/ct/show/NCT00125996; NCT00125996).

Nonhematological benefits of iron

Iron deficiency anemia is common in people with chronic kidney disease (CKD) and its importance in supporting erythropoiesis is unquestioned especially in those patients treated with erythropoietin. Clinical symptomatology such as fatigability, cold intolerance, failure to concentrate and poor effort intolerance is often attributed to anemia or uremia. That iron deficiency, per se, can cause these symptoms is poorly recognized. Clinical and animal studies that support the benefits of iron supplementation, independent of increasing hemoglobin, such as those on immune function, physical performance, thermoregulation, cognition, and restless leg syndrome and aluminum absorption is the subject of this narrative review.

Extruded rice fortified with micronized ground ferric pyrophosphate reduces iron deficiency in Indian schoolchildren: a double-blind randomized controlled trial

BACKGROUND

Iron fortification of rice could be an effective strategy for reducing iron deficiency anemia in South Asia.

OBJECTIVE

We aimed to determine whether extruded rice grains fortified with micronized ground ferric pyrophosphate (MGFP) would increase body iron stores in children.

DESIGN

In a double-blind, 7-mo, school-based feeding trial in Bangalore, India, iron-depleted, 6-13-y-old children (n = 184) were randomly assigned to receive either a rice-based lunch meal fortified with 20 mg Fe as MGFP or an identical but unfortified control meal. The meals were consumed under direct supervision, and daily leftovers were weighed. All children were dewormed at baseline and at 3.5 mo. Iron status and hemoglobin were measured at baseline, 3.5 mo, and 7 mo.

RESULTS

At baseline, the prevalences of iron deficiency and iron deficiency anemia in the total sample were 78% and 29%, respectively. After 7 mo of feeding, there was a significant increase in body iron stores in both study groups (P < 0.001), with a greater increase in the iron group than in the control group (P < 0.05). There was a significant time x treatment interaction for iron deficiency, which fell from 78% to 25% in the dewormed iron group and from 79% to 49% in the dewormed control group. Iron deficiency anemia decreased from 30% to 15% (NS) in the iron group but remained virtually unchanged in the control group (28% and 27%). In sensory tests, the MGFP-fortified rice (fortified at 3 and 5 mg Fe/100 g) was indistinguishable from natural rice, in both cooked and uncooked form.

CONCLUSIONS

Extruded rice fortified with MGFP has excellent sensory characteristics. Fed in a school lunch meal, it increases iron stores and reduces the prevalence of iron deficiency in Indian children.

Prevalence of iron deficiency and iron deficiency anemia among three populations of female military personnel in the US Army

BACKGROUND

Iron deficiency is the most prevalent micronutrient deficiency disease in the world and occurs in young women in the United States. Female military personnel represent a unique population faced with intense physical and cognitive demands.

OBJECTIVE

The objective of this study was to determine the prevalence of iron deficiency and iron deficiency anemia among three populations of female military personnel in the US Army.

METHODS

Iron status was assessed in 1216 volunteers. Volunteers were recruited from three groups: immediately following initial entry to the Army (IET), immediately following basic combat training (AIT), or following at least six months of permanent assignment (PP). Iron deficiency was determined using a three variable model, including cut-off values for serum ferritin, transferrin saturation, and red cell distribution width (RDW). Iron deficiency anemia was categorized by iron deficiency and a hemoglobin (Hgb) value of <12 g/dL.

RESULTS

The prevalence of iron deficiency was greater in women in the AIT group (32.8%) than in the IET and PP groups (13.4 and 9.6%, respectively). The prevalence of iron deficiency anemia was greater in the AIT group (20.9%) than in the IET and PP groups (5.8 and 4.8%, respectively). Furthermore, the prevalence of iron deficiency anemia was greater in Hispanic (21.9%) and African-American military personnel (22.9%) than in Caucasian military personnel (10.5%).

CONCLUSIONS

These data indicate that female military personnel experience diminished iron status following training, and that iron nutriture is an important issue facing females in the military.

Iron supplementation maintains ventilatory threshold and improves energetic efficiency in iron-deficient nonanemic athletes

OBJECTIVE

To determine the effect of iron supplementation on iron status and endurance capacity.

DESIGN

Randomized, double-blind iron supplementation.

SETTING

University of Missouri-Columbia and surrounding community.

SUBJECTS

Twenty iron-deficient (serum ferritin, sFer<16 microg/l; serum transferrin receptor, sTfR>8.0 mg/l; or sTfR/log sFer index >4.5), nonanemic (hemoglobin, Hb>120 g/l, women; >130 g/l, men) men and women (18-41 years) were recruited via fliers and newspaper advertisements; 20 of 31 eligible subjects participated.

INTERVENTIONS

A 30 mg measure of elemental iron as ferrous sulfate or placebo daily for 6 weeks.

RESULTS

Dietary iron intake and physical activity did not differ between groups before or after supplementation. Iron supplementation significantly increased sFer compared to placebo (P=0.01), but did not affect Hb or hematocrit. Iron supplementation prevented the decline in ventilatory threshold (VT) observed in the placebo group from pre- to post-supplementation (P=0.01); this effect was greater in individuals with lower sFer before intervention (P<0.05). Changes in sFer from pre- to post-treatment were positively correlated with changes in VT (P=0.03), independent of supplementation. The iron group significantly increased gross energetic efficiency during the submaximal test (P=0.04). Changes in sFer were negatively correlated with changes in average respiratory exchange ratio during the submaximal test (P<0.05).

CONCLUSIONS

Iron supplementation significantly improves iron status and endurance capacity in iron-deficient, nonanemic trained male and female subjects.

Iron-regulatory protein hepcidin is increased in female athletes after a marathon

The propose of this study was to determine the influence of marathon race on hepcidin excretion in female athletes (age 26-45 years). Urine samples were taken before, immediately after, 1 and 3 days after the race. In the average, hepcidin transiently increased at day 1 from 32 to 85 ng/mg creatinine. We propose that the frequently observed iron deficiency of females runners is caused by elevated hepcidin levels.

Hematologic Disorders in the Athlete

Optimal athletic performance depends on proper function of many organs, including the blood. This is underscored by the focus of endurance athletes on increased hemoglobin through training at altitude or exogenous erythropoietin. Several other aspects of the hematologic system can also affect or be influenced by physical activity. In this article, the authors briefly discuss inherited abnormalities of the blood that can manifest themselves in athletes. We then discuss the effects of exercise on the blood, and acquired abnormalities of blood cells or coagulation parameters that occur in athletes, and that can influence performance or cause other symptoms.

Micronutrient requirements of physically active women: what can we learn from iron?

The health benefits of physical activity are well established and there is increasing recognition of the importance of fitness as a key modulator of chronic disease. The impact of physical activity on micronutrient requirements is a topic of tremendous interest to the lay public, but the interest is in sharp contrast to data from well-designed studies. Research in this area is poorly controlled for nutritional status of the participants, standardized exercise protocols, markers and cutoff points for measurement of micronutrient status, and variability in subject characteristics. The micronutrient status of women in the general population is of concern, but it is not clear that physical activity increases the requirement of most micronutrients. When dietary intake is adequate, the results of most studies are either equivocal or show no benefit to performance of supplementation. In the few instances where exercise does appear to increase an individual's requirement, the increase can be obtained within the additional calories required for energy balance. In the absence of consistent data, micronutrient supplementation is often indiscriminate without regard to nutrient status. Because iron is such a key nutrient for physical activity, and the status in women is often compromised, it serves as a useful example of how current research limits the ability to make recommendations regarding the impact of exercise on micronutrients requirements in women. With the recent recognition of the importance of physical activity to the prevention and treatment of chronic diseases through the life span, more attention should be focused on the impact of exercise on micronutrient requirements, especially in the context of weight loss regimens.

Iron deficiency: a concise review

Iron deficiency is a major worldwide health problem. There is recent evidence that the anemia is only the last manifestation of the syndrome and that symptoms occur before the anemia is manifest. Advances in outlining the physiology of iron deficiency have been made, gaps remain in the current understanding. While oral iron supplement remains the mainstay, some indications for the intravenous administration have developed. This review will highlight the epidemiology, physiology, clinical presentation, and treatment options.