Total Body Iron Stores Research Articles

Inadequate Dietary Intake in Patients with Thalassemia

BackgroundPatients with thalassemia have low circulating levels of many nutrients, but the contribution of dietary intake has not been assessed. ObjectiveOur objective was to assess dietary intake in a large contemporary sample of subjects with thalassemia. DesignA prospective, longitudinal cohort study using a validated food frequency questionnaire was conducted. Participants/settingTwo hundred and twenty-one subjects (19.7±11.3 years, 106 were female) were categorized into the following age groups: young children (3 to 7.9 years), older children/adolescents (8 to 18.9 years), and adults (19 years or older); 78.8% had β-thalassemia and 90% were chronically transfused. This study took place at 10 hematology outpatient clinics in the United States and Canada. Main outcome measuresWe conducted a comparison of intake with US Dietary Reference Intakes and correlated dietary intake of vitamin D with serum 25-OH vitamin D and dietary iron with total body iron stores. Statistical analyses performedIntake was defined as inadequate if it was less than the estimated average requirement. χ2, Fisher's exact, and Student's t test were used to compare intake between age categories and logistic regression analysis to test the relationship between intake and outcomes, controlling for age, sex, and race. ResultsMore than 30% of subjects consumed inadequate levels of vitamin A, D, E, K, folate, calcium, and magnesium. The only nutrients for which >90% of subjects consumed adequate amounts were riboflavin, vitamin B-12, and selenium. Dietary inadequacy increased with increasing age group (P<0.01) for vitamins A, C, E, B-6, folate, thiamin, calcium, magnesium, and zinc. More than half of the sample took additional supplements of calcium and vitamin D, although circulating levels of 25-OH vitamin D remained insufficient in 61% of subjects. Dietary iron intake was not related to total body iron stores. ConclusionsSubjects with thalassemia have reduced intake of many key nutrients. These preliminary findings of dietary inadequacy are concerning and support the need for nutritional monitoring to determine which subjects are at greatest risk for nutritional deficiency. Future research should focus on the effect of dietary quality and nutritional status on health outcomes in thalassemia.

Diagnosis of Iron Overload and Heart Disease by Magnetic Resonance Imaging

The use of Magnetic resonance imaging (MRI) to estimate tissue iron was initiated nearly three decades ago but has only become a practical reality in the last ten years. MRI is most often used to estimate hepatic and cardiac iron in patients with thalassemia or sickle cell disease and has largely replaced liver biopsy for liver iron quantification. The ability of MRI to image extra hepatic organs has really transformed our understanding of iron mediated toxicity in transfusional siderosis. For decades, iron cardiomyopathy was the leading cause of death in thalassemia major, but it is now relatively rare in centers with regular MRI screening. Early recognition of cardiac iron loading allows more gentle modifications of iron chelation therapy prior to life threatening organ dysfunction. Serial MRI evaluations have demonstrated differential kinetics of uptake and clearance among the difference organs of the body. Although elevated serum ferritin and liver iron concentration increase the risk of cardiac and endocrine toxicities, extra hepatic iron deposition and toxicity occurs in many patients despite having low total body iron stores; there is no safe liver iron level in chronically transfused patients. Instead, the type, dose, and pattern of iron chelation therapy all contribute to whether cardiac iron accumulation will occur. These observations, coupled with the advent of increasing options for iron chelation therapy, are allowing clinicians to more appropriately tailor chelation therapy to individual patient needs, producing greater efficacy with fewer toxicities. With the decline in cardiac mortality, future frontiers in MRI monitoring including better prevention of endocrine toxicities, particularly hypogonadotropic hypogonadism and diabetes. These organs also serve as early warning signals for inadequate control of non-transferrin bound iron, a risk factor for cardiac iron loading. Thus MRI assessment of extra hepatic iron stores is a critical monitoring tool for chronically transfused patients. Further prospective work is necessary to determine whether markers of endocrine and exocrine pancreatic function can be used as surrogates of cardiac risk in regions where MRI is not available.

Iron Sucrose Promotes Endothelial Injury and Dysfunction and Monocyte Adhesion/Infiltration

Background/Aims: Intravenous (IV) iron preparations are widely used in the management of anemia in ESRD populations. Recent changes in reimbursement policy have dramatically increased the use of IV iron to lower the use of costly erythropoiesis-stimulating agents. These preparations are frequently administered with insufficient attention to the total body iron stores or presence of inflammation which is aggravated by excess iron. Endothelial injury and dysfunction are critical steps in atherosclerosis, thrombosis and cardiovascular disease. IV iron preparations raise plasma non-transferrin-bound iron which can promote oxidative stress, endothelial damage and dysfunction. We explored the effect of an IV iron preparation on endothelial cells, monocytes and isolated arteries. Methods: Primary cultures of human aortic endothelial cells (HAEC) were treated with pharmacologically relevant concentrations of iron sucrose (10–100 µg/ml) for 4–24 h. Endothelial cell morphology, viability, and monocyte adhesion were tested. Endothelial function was assessed by measuring the vasorelaxation response to acetylcholine in normal rat thoracic aorta rings preincubated with iron sucrose (200 µg/ml). Results: In contrast to the control HAEC which showed normal cobblestone appearance, cells treated with iron sucrose (50–100 µg/ml) for 4 h showed loss of normal morphological characteristics, cellular fragmentation, shrinkage, detachment, monolayer disruption and nuclear condensation/fragmentation features signifying apoptosis. HAEC exposure to iron sucrose (10–100 µg/ml) increased monocyte adhesion 5- to 25-fold. Incubation in media containing 200 µg/ml iron sucrose for 3 h caused marked reduction in the acetylcholine-mediated relaxation in phenylephrine-precontracted rat aorta. Conclusion: Pharmacologically relevant concentration of iron sucrose results in endothelial injury and dysfunction and marked increase in monocyte adhesion.

Impact of Iron Assessment by MRI

The use of magnetic resonance imaging (MRI) to estimate tissue iron was conceived in the 1980s, but has only become a practical reality in the last decade. The technique is most often used to estimate hepatic and cardiac iron in patients with transfusional siderosis and has largely replaced liver biopsy for liver iron quantification. However, the ability of MRI to quantify extrahepatic iron has had a greater impact on patient care and on our understanding of iron overload pathophysiology. Iron cardiomyopathy used to be the leading cause of death in thalassemia major, but is now relatively rare in centers with regular MRI screening of cardiac iron, through earlier recognition of cardiac iron loading. Longitudinal MRI studies have demonstrated differential kinetics of uptake and clearance among the difference organs of the body. Although elevated serum ferritin and liver iron concentration (LIC) increase the risk of cardiac and endocrine toxicities, some patients unequivocally develop extrahepatic iron deposition and toxicity despite having low total body iron stores. These observations, coupled with the advent of increasing options for iron chelation therapy, are allowing clinicians to more appropriately tailor chelation therapy to individual patient needs, producing greater efficacy with fewer toxicities. Future frontiers in MRI monitoring include improved prevention of endocrine toxicities, particularly hypogonadotropic hypogonadism and diabetes.

Relationship Between Total Iron Removed by Phlebotomy and Iron Removed From the Liver in Pediatric Thalassemia Major Patients Following Curative Stem Cell Transplant

Abstract 5300 Background:Patients with thalassemia major (TM) who have undergone hematopoietic stem cell transplantation (HSCT) often demonstrate iron overload due to their previous requirement for regular blood transfusions, and are therefore at risk of associated toxicities. Efficient iron removal in such patients is therefore essential to prevent complications. For patients post-HSCT who undergo iron removal with phlebotomy, analysis of liver volume in combination with measurement of liver iron concentration (LIC) by MRI enables a calculation of total liver iron content (TLIC) in units of g Fe (in contrast to LIC in units of mg Fe/g tissue) both before and after phlebotomy. The aim of the study was to determine the average fraction of the Hb iron removed represented by the reduction in TLIC. Methods:LB03T is a prospective, randomized trial enrolling children aged 2-<18 years with TM who had undergone HSCT. Patients were chelation-naïve, hepatitis B- and C-negative, with confirmed iron overload (serum ferritin ≥500 ng/mL on ≥2 monthly occasions, and LIC >3 mg Fe/g dry weight [dw]). Eligible patients were randomized to phlebotomy (6 mL/kg blood/2 weeks) or deferasirox (10 mg/kg/day starting dose; 5 mg/kg/day adjustments up to 20 mg/kg/day were permitted). A primary study endpoint was change in LIC assessed using spin-density projection assisted R2-MRI (FerriScan®). For the patients undergoing phlebotomy, liver iron content was calculated as [liver volume] × [LIC]. A wet to dry weight conversion factor (3.8) was then applied, to transform the LIC into units of mg Fe/g wet tissue. The density of liver tissue was assumed as 1.051 g/mL, from which the TLIC was estimated. TLIC was calculated before and after phlebotomy to reduce iron overload, which enabled the total iron reduction in the liver to be calculated. Results:A total of 27 patients were randomized to deferasirox (n=12) or phlebotomy (n=14). One patient randomized to phlebotomy refused treatment. The results presented here refer to the patients in the phlebotomy arm only. The median time between MRI scans was 405 days (range: 254–632). The initial median LIC and TLIC were 7.4 (range: 3.1–24.0) mg/g dw and 2.6 (range: 0.6–7.4) g. Thirteen of the 14 subjects showed a response to phlebotomy therapy with LIC and TLIC decreasing with phlebotomy therapy. One subject (LIC 24.0 mg/g dw and TLIC 7.4 g) did not respond to phlebotomy therapy and showed an increase in both LIC and TLIC to 33.5 mg/g dw and 10.95 g respectively over a period of 425 days. For the 13 subjects who responded to phlebotomy therapy, there were significant correlations between reduction in LIC and grams of Hb iron phlebotomized (r2=0.41; P=0.02) and between reduction in TLIC and grams of Hb iron phlebotomized (r2=0.79; P<0.0001) (see Figure 1). The mean fraction of the phlebotomized Hb iron represented by the reduction in TLIC for the 13 responders was 71%. [Display omitted] Conclusions:Liver volume data combined with LIC measured by MRI enables a calculation of TLIC. In pediatric post-HSCT patients with TM undergoing phlebotomy, a significant linear correlation was found between reduction in TLIC and grams of Hb iron phlebotomized thereby rendering TLIC a useful and noninvasive tool for calculating the total body iron stores in this patient group. Disclosures:Inati:Novartis: Honoraria, Research Funding, Speakers Bureau. Taher:Novartis: Honoraria, Research Funding. St Pierre:Resonance Health: Consultancy, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Patents & Royalties, Speakers Bureau.

Serum ferritin levels are associated with metabolic syndrome in postmenopausal women but not in premenopausal women

Ferritin, a marker of total body iron stores, is known to be associated with the risk of having metabolic syndrome and has been demonstrated to increase after the onset of menopause. Postmenopause status is an important determinant of metabolic syndrome. The aim of this study was to perform a menopause status-specific analysis of the association between ferritin levels and metabolic syndrome. We conducted a cross-sectional study of 3,082 participants (1,691 premenopausal women and 1,391 postmenopausal women), all of whom were enrolled in the Korean National Health and Nutrition Examination Survey 2007. Premenopausal and postmenopausal women with metabolic syndrome had higher ferritin levels than did those without metabolic syndrome. After adjustments for age; body mass index; alcohol intake; smoking history; exercise; hormone therapy use; hemoglobin, aspartate aminotransferase, and alanine aminotransferase levels; and intake of energy and iron, multivariate logistic regression analysis revealed that postmenopausal women with ferritin levels in the third tertile had an increased risk of having metabolic syndrome (odds ratio, 1.62; 95% CI, 1.04-2.81) compared with postmenopausal women with levels in the first quartile. No such association was detected in premenopausal women. Increased ferritin levels may be a determinant for metabolic syndrome in postmenopausal women but not in premenopausal women.

Intravenous iron and pulmonary hypertension in intensive care

Dear Editor, We read with interest the case reported by Weber-Carstens et al. [1] of a woman with longstanding idiopathic pulmonary arterial hypertension who presented with severe polytrauma. Her admission was complicated by critical hypoxia and severe acute-onchronic pulmonary hypertension resulting in acute right heart decompensation. During this life-threatening phase, the authors report that the benefits of standard combination therapy in reducing right ventricular afterload were short-lived in the face of worsening hypoxia. Recent work from our group and others has introduced the possibility that intravenous iron may provide additional benefit in this setting. In healthy iron-replete men studied over 1 week at high altitude (equivalent to sea level FiO2 *0.12) we found that established hypoxiainduced pulmonary hypertension was significantly reversed by a single 200 mg dose of intravenous iron sucrose [2]. This effect was evident within 4 h of infusion—rapid enough to be of possible benefit in offloading the right ventricle in the acute clinical setting. We also studied patients with chronic mountain sickness over 1 month at high altitude and found that depletion of iron by venesection was associated with worsening pulmonary hypertension despite a large reduction in haematocrit (although this effect was not immediately reversed by subsequent iron infusions) [2]. This work was preceded by an 8-h laboratory study of healthy ironreplete volunteers in which the increase in pulmonary arterial pressure caused by hypoxia was blunted by prior intravenous infusion of iron sucrose (200 mg), while the pulmonary vascular response to hypoxia was enhanced by reduction of iron availability with desferrioxamine [3]. The dose of iron used in these studies is small relative to total body iron stores (approximately 4 g), and current intravenous formulations such as iron sucrose are very safe. These studies indicate that hypoxic pulmonary hypertension can be attenuated by increasing iron availability and exacerbated by decreasing iron availability. This interaction between iron, hypoxia and the pulmonary circulation is consistent with known effects of iron on the hypoxiainducible factor (HIF) family of transcription factors and involvement of HIF in regulating cardiopulmonary physiology [2–4]. Studies from several centres have subsequently confirmed a link between iron status and idiopathic pulmonary arterial hypertension, demonstrating that iron deficiency is unexpectedly common in this disease and independently worsens morbidity and mortality (recently reviewed by Rhodes et al. [5]). Two European studies investigating the use of intravenous iron in pulmonary arterial hypertension are now underway [5]. We look forward to the results of these and other studies. In the meantime, the available evidence raises the possibility that intravenous iron may be beneficial as a rescue therapy when hypoxia and pulmonary hypertension are acutely life-threatening and conventional treatment is inadequate.

Study of the effect of iron overload on the function of endocrine glands in male thalassemia patients

Background:Iron overload is an important issue in the state of thalassemic patients due to the harmful effect of high concentration of iron deposited in different tissues in human body including endocrine glands. In the present work, an attempt is carried out to estimate the effect of iron overload in thalassemic patients on the function of endocrine glands through the estimation of their ability to secrete adequate amounts of certain hormones.Materials and Methods:Seventy eight male children with beta-thalassemia, in the age-group of 4–11 years, were enrolled for this research. These children were being treated with frequent transfusions and long-term iron chelation therapy. Thirty age and sex matched children without thalassemia constituted the control group. Ferritin and different hormones were estimated by ELISA technique.Results:The results showed a mild reduction in the function of endocrine glands through the decrease in the level of some hormones. These changes due mainly to the hypoxia and precipitation of iron in certain glands and overlapping with the synthesis or secretion of the hormones.Conclusion:There is a different hormonal disturbances in beta thalassemia patients. Reduction of total body iron store is an important goal of the treatment of thalassemia and measuring the hormones concentration is necessary for the follow up of the thalassemic patients especially during puberty.

Iron Overload Indices In Thalassemia Major Children Cured by Stem Cell Transplantation at Enrollment In a Prospective Randomized Trial Comparing Phlebotomy and Deferasirox

AbstractAbstract 2082 Introduction:Stem cell transplantation(SCT) is the only available cure for patients with thalassemia major (TM). Transfusional iron overload is a common complication with SCT. Data defining the natural history of iron overload, its impact on morbidity and mortality, and its treatment in transplant recipients is limited. There are currently no randomized trials addressing post SCT iron removal in children with TM. This prospective randomized trial will compare the efficacy, safety, and convenience of phlebotomy versus deferasirox for the treatment of iron overload in children with TM who have undergone allogeneic SCT. Patients and methods:Chelation naïve patients between 2 – <20 years of age with a serum ferritin (SF) level ≥500 ng/ml on at least 2 monthly occasions, and a liver iron concentration (LIC) >3 mg Fe/g dry liver weight (dw) as determined by R2 MRI will be randomized to two groups: phlebotomy or deferasirox. The starting dose of deferasirox will be 10 mg/kg/day adjusted every 3 months in increments of 5 mg/kg to a maximum dose of 20 mg/kg/day according to monthly SF and its trend. For phlebotomy, 6 ml/kg of blood will be withdrawn every 2 weeks. The amount of blood removed during each phlebotomy session will be recorded, and the hemoglobin and iron concentrations will be calculated. Correlation between total body iron stores (TBISs) and LIC will be undertaken. Patients will undergo monthly SF, quarterly serum/urine iron, and yearly cardiac echo, liver R2 and cardiac T2* MRI measurement. Continuous adverse event monitoring will be made. Total liver iron content will be determined by R2 MRI and liver volume measurement. Quality of life (QoL) will be measured by the PEDSQL questionnaire. Treatment duration will be one year but interrupted if SF drops below 300 ng/ml and/or with major adverse events. We herein describe baseline characteristics of 27 chelation naïve, hepatitits C and B negative children with TM (16 males, 11 females) cured by SCT from an HLA-identical family member (unrelated donor in 1 patient) who are enrolled in the above trial. Result:Patients' characteristics at enrollment are outlined in Table 1. Ten patients (37.0%) had SF <1000 ng/ml, 11 (40.8%) had SF 1000–2500 ng/ml, while 6 (22.2%) had SF >2500 ng/ml. Twelve patients (44.4%) had LIC 3-<7 mg Fe/g dw, 8 (29.6%) had LIC 7–15 mg Fe/g dw, while 7 (26.0%) had LIC >15 mg Fe/g dw. Five (18.5%) patients had cardiac T2* <20 msec. Overall, 9 patients (33.3%) had significant iron overload defined as SF >2500 ng/ml, or LIC >15 mg Fe/g dw, or T2* <20 msec. On multivariate regression, predictors of change in SF at enrollment relative to transplant were: SF and LIC (P<0.05); whereas predictors of change in LIC at enrollment relative to transplant were: SF, LIC, and total number of transfusions (TNT) (P<0.05). The change in LIC correlated negatively with LIC at SCT (Pearson's correlation, r=-0.52; P=0.006). A negative change in LIC was observed with an LIC at SCT of 10 mg Fe/g dw and above (Figure 1). There were no statistically significant correlations between cardiac T2* and any of LIC, SF, or TNT; or between LIC and any of age, risk, class, or gender. Conclusion:This report sheds light on the natural history of post transplant iron overload in children cured of TM and underscores the fact that such children continue to have iron overload for years post treatment. It also highlights correlations between SF, LIC, and TNTs in this setting. As the trial continues enrolling more patients, it is expected to generate important data comparing 2 modalities of iron overload treatment (deferasirox vs. phlebotomy) in this patient population.Table 1Patients' characteristics at enrollment.ParameterMedianRangeAge (years)12.483.12–19.62Follow up post SCT (years)3.11.2–4.6Hemoglobin (g/dl)12.29.9–15.9Total number of transfusions (n)8825–330SF (ng/ml)1144.3502.5–5884Liver volume (ml)1251.2553.8–2111LIC (mg Fe/g dw)8.33.1–36.6Cardiac T2* (msec)27.88.5–41.5Ejection fraction (%)6858–75Serum iron (ìg/dl)131.243.5–307.5Total iron binding capacity (ìg/dl)246.5189.5–336.2Transferrin (%)1.791.09–2.47Alanine aminotransferase(IU/l)2418.9–78Aspartate aminotransferase (IU/l)24.49.9–214.5Blood urea nitrogen (mg/dl)13.56.9–22Creatinine (mg/dl)0.450.27–0.68Creatinine clearance (ìM/l)12355.9–545Microalbuminuria (mg/24 hrs)10.13.5–403.5 [Display omitted] Disclosures:Inati:Novartis Pharmaceuticals: Speakers Bureau. St Pierre:Resonance Health: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau. Taher:Novartis Pharmaceuticals: Speakers Bureau.

Efficacy and Safety of Iron Administration in Juvenile Populations

Infantile iron deficiency anemia (IDA) reduces maximal lifetime cognitive capacity and can threaten the life of an adolescent mother in childbirth. Administration of iron is a component of strategies for preventing or reversing iron deficiency (ID) and iron can be given parenterally or as oral supplements or fortified food. Safety issues can arise at the point of administration, i.e. in the gut lumen, and as a consequence of excessive iron stores arising from the interventions. Recent improvements in the pharmacology of parenteral iron compounds open the way to greater consideration of the intravenous route in pediatric therapy, and even public health. Oral iron supplementation, usually with folic acid, is the main treatment of IDA in the clinical setting. It is often combined with multiple micronutrients and is also used for resolution of severe anemia at the community level and for prophylaxis in the nonanemic population. Fortification of staple food (such as flour), or age-specific foods (infant formula, complementary foods) and beverages are the usual methods for ID prophylaxis. Special iron-rich preparations (powders, crushable tablets, edible spreads) are available for home fortification. Biofortification, i.e. enriching the iron content of crops during cultivation, is a novel approach, yet to be fully implemented or evaluated for children. Side effects and toxicity after oral iron intake are seen in the gut lumen. After oral and parenteral iron intake, the rise in circulating iron can increase the risk of complications from coexisting infections, notably with malaria, and when individual iron status is adequate. Growth impairment occurs with exposure of iron-sufficient children to iron interventions, so that targeting of iron to ID individuals seems advisable. Numerous adverse consequences from accumulation of excessive total body iron stores show up as a consequence of iron-mediated oxidative stress. Incomplete maturation of iron homoeostasis may permit higher iron absorption before 6 months of age.

The effect of deferasirox on cardiac iron in thalassemia major: impact of total body iron stores

AbstractWe present results from a prospective, multicenter, open-label, single-arm study evaluating response of cardiac and liver iron to deferasirox therapy for 18 months. Twenty-eight patients with abnormal T2* and normal left ventricular ejection fraction were enrolled from 4 US centers. All patients initially received deferasirox doses of 30 to 40 mg/kg per day. Patients were severely iron overloaded: mean liver iron concentration (LIC) 20.3 mg Fe/g dry weight, serum ferritin 4417 ng/mL, and cardiac T2* 8.6 ms. In the intent-to-treat population, 48% reached the primary endpoint (cardiac T2* improvement at 18 months, P = not significant). There were 2 deaths: 1 from congestive heart failure and 1 from sepsis. In the 22 patients completing the trial, LIC and cardiac T2* improvements were 16% (P = .06) and 14% (P = .07), respectively. Cardiac T2* improvement (13 patients) was predicted by initial LIC, final LIC, and percentage LIC change, but not initial cardiac T2*. Cardiac iron improved 24% in patients having LIC in the lower 2 quartiles and worsened 8.7% in patients having LIC in the upper 2 quartiles. Left ventricular ejection fraction was unchanged at all time points. Monotherapy with deferasirox was effective in patients with mild to moderate iron stores but failed to remove cardiac iron in patients with severe hepatic iron burdens. This study was registered at www.clinicaltrials.gov as #NCT00447694.

Liver iron content determination by magnetic resonance imaging

Accurate evaluation of iron overload is necessary to establish the diagnosis of hemochromatosis and guide chelation treatment in transfusion-dependent anemia. The liver is the primary site for iron storage in patients with hemochromatosis or transfusion-dependent anemia, therefore, liver iron concentration (LIC) accurately reflects total body iron stores. In the past 20 years, magnetic resonance imaging (MRI) has emerged as a promising method for measuring LIC in a variety of diseases. We review the potential role of MRI in LIC determination in the most important disorders that are characterized by iron overload, that is, thalassemia major, other hemoglobinopathies, acquired anemia, and hemochromatosis. Most studies have been performed in thalassemia major and MRI is currently a widely accepted method for guiding chelation treatment in these patients. However, the lack of correlation between liver and cardiac iron stores suggests that both organs should be evaluated with MRI, since cardiac disease is the leading cause of death in this population. It is also unclear which MRI method is the most accurate since there are no large studies that have directly compared the different available techniques. The role of MRI in the era of genetic diagnosis of hemochromatosis is also debated, whereas data on the accuracy of the method in other hematological and liver diseases are rather limited. However, MRI is a fast, non-invasive and relatively accurate diagnostic tool for assessing LIC, and its use is expected to increase as the role of iron in the pathogenesis of liver disease becomes clearer.

Quantitative CT Accurately Predicts Liver Iron Concentration in Transfusional Siderosis.

Abstract 4053Poster Board III-988 IntroductionHemoglobinopathies are among the most common genetic diseases in the work. Many hemoglobinopathy patients require lifeline transfusion, iron chelation, and careful monitoring of iron stores. Liver iron concentration (LIC) is an excellent metric of transfusional iron balance and total body iron stores(1). Noninvasive LIC estimation by MRI is gradually replacing liver biopsy but remains limited by cost and availability, particularly in regions where thalassemia is prevalent(2). Quantitative computed tomography (QCT) was proposed as a means to estimate LIC 30 years ago, but there has been surprisingly limited validation(3-5). QCT is cheaper and more available than MRI. Steady improvements in CT instrumentation and standardization warrant a re-evaluation of QCT for iron quantitation. In this study, we determined liver attenuation as a function of MRI-predicted liver iron concentration in 45 patients over a 6 year period. MethodsThis study represents a convenience sample of all iron-overloaded patients who had undergone both QCT for bone density and LIC measurement by MRI at Children's Hospital Los Angeles. 64 usable observations were obtained in 45 patients; 14 patients had multiple exams(range 2-6). MRI and QCT examinations were considered “paired” if the scans were less than 120 days apart (59 studies). MRI liver R2 and R2* examinations were performed and analyzed as previously described(2).Quantitative CT was performed on a General Electric Hilite Advantage. A single axial 10 mm thick slice was collected at the L1 level using a KVp of 80 at 70 mA for 1 second. Three hydroxyappetite phantoms, calibrated to 0, 125, and 250 Hounsfield units, were placed in scanning platform (CT-T bone densitometry package; GE Medical Systems), approximately 7 cm from mid-vertebral body. Calibration curve was obtained from regions of interest drawn within the three phantoms, using linear regression calculated by custom MATLAB routines. Regions of interest in the liver were drawn in ∼ 9 cm2 regions of the right and left lobe of the liver, as well as a region encompassing the entire cross-sectional area of the liver. ResultsMost patients had thalassemia major and moderate to severe iron overload, with a LIC of 14.1 ± 14 mg/g dry weight and a cardiac R2* of 70.5 ± 95.0 Hz (median T2* of 30.9 ms). Patients who were receiving regular transfusions were well transfused, with a pre-transfusion hemoglobin of 9-9.5 g/dl. All chronically transfused patients were using deferoxamine until approximately 2005, with most switching to deferasirox in 1/2005.Figure 1 demonstrates MRI-predicted LIC as a function of liver attenuation. There is a strong linear relationship having a slope of 0.591 mg/g dry weight of liver per HU. Normal liver attenuation ranges in non iron overload children and young adults is 57-76 HU. Upper limit of normal corresponds to a predicted LIC of 6 m/g, indicating an intrinsic lack of sensitivity for qCT at low iron concentrations. Time-courses of CT-iron relationship from 14 patients whom had serial evaluations paralleled the regression line and were well constrained by the 95% confidence intervals, suggesting the calibration is suitable for serial analysis (not shown). Whole liver attenuation values were unbiased with respect to values from the right and left lobe; coefficient of variation was 2.2-4.9%. ConclusionThe present work represents the largest human validation of QCT for liver iron quantitation. QCT techniques have inadequate sensitivity to discriminate LIC values less than 6 mg/g but are not limited by high iron concentrations. High reproducibility makes them suitable for tracking serial LIC changes. QCT may be an acceptable surrogate for LIC in hospitals lacking the software, personnel, or financial resources to support MRI or SQUID LIC measurements. [Display omitted] Acknowledgments: This work supported by NIH HL075592, CDC (U27/CCU922106) and GCRC (NIH #RR00043-43). Disclosures:No relevant conflicts of interest to declare.

History and Current Impact of Cardiac Magnetic Resonance Imaging on the Management of Iron Overload

In this issue of Circulation , researchers from the Royal Brompton Hospital and University College London have published a long-anticipated report on the ability of magnetic resonance imaging (MRI) to predict cardiac dysfunction in transfusional siderosis.1 Article see p 1961 Briefly, they report that a cardiac T2* value <10 ms had a sensitivity of 98% and a specificity of 86% for prediction of symptomatic heart failure in 1 year. Risk was graded with respect to T2*, with 47% of patients having T2* <6 ms developing cardiac failure in the same interval. Similar, but less striking, risk stratification was also observed for prospective arrhythmia risk. Metrics of total body iron stores, liver iron concentration, and serum ferritin performed little better than chance in predicting heart failure. To place these observations in context, it is important to review iron overload and its past and present management. Iron overload is a surprisingly common clinical problem, occurring through increased iron absorption (primary hemochromatosis) or through frequent blood transfusion therapy (secondary hemochromatosis).2 Primary hemochromatosis disorders, such as hfe mutations, are relatively common in white populations. However, variable hfe gene penetrance, increased genetic surveillance, and severity of noncardiac symptoms result in fewer hereditary hemochromatosis patients presenting with iron-mediated cardiac disease. By contrast, iron cardiomyopathy remains a major cause of death in secondary hemochromatosis disorders such as the thalassemia, Blackfan-Diamond anemia, and myelodysplastic syndromes because the iron-loading rates are many-fold greater than for primary hemochromatosis.3 The hemoglobinopathies are the most common genetic disorders in the world, particularly in regions where malaria is or was previously endemic, such as the Mediterranean, northern Africa, the Middle East, and Southeast Asia. Increasing economic and ethnic globalization has increased the importance of these disorders in the United States, and their impact is increasing. Iron overload is also becoming …

Iron Metabolism, Iron Deficiency, Thrombocytosis, and the Cardiorenal Anemia Syndrome

In treating moderate to severe anemia of chronic kidney disease (CKD), oral iron is effective only in a minority of nondialysis patients. Intravenous iron is more effective and can raise levels of hemoglobin even without the use of erythropoiesis-stimulating agents (ESAs). Unfortunately, the current assays of iron status that are presently widely available are not especially helpful in predicting response. In patients on dialysis, i.v. iron is effective over a wide range of serum ferritin from <100 ng/ml to 800 ng/ml. None of the three available randomized controlled trials comparing oral with i.v. iron showed evidence of nephrotoxicity caused by i.v. iron. Iron deficiency is a risk factor for thrombocytosis and should, wherever possible, be avoided. Optimal coadministration of iron may reduce the risk for ESA-driven cardiovascular events. Increased total body iron stores (imperfectly reflected by serum ferritin levels in CKD) do not appear to be related to such events or hospitalization in CKD; it is unclear what other risk factors and mechanisms need to be considered. In the appreciable proportion of patients with both renal and cardiac dysfunction, management is further complicated by a vicious circle (which can be characterized as cardiorenal anemia syndrome) in which CKD, heart failure, and anemia exacerbate each other. In such patients, correction of anemia appears to improve cardiac function and quality of life without a greater risk for adverse events.

Iron: The fifth horseman of the apocalypse?

Hematologists are under increasing pressure to prescribeiron chelation for seemingly any patient being transfused.In the week before writing this editorial, I received 10 mail-ers and emails warning me of the dangers of iron overloadfor a variety of patient types and disease states. However,in reviewing the data, it is very unclear the true risks oftransfusion-related iron overload—a necessary first stepbefore considering expensive and potentially toxic therapy.The most abundant support for iron chelation in heavilytransfused patients is in thalassemia [1]. Although transfu-sions can prolong survival, after years endocrinopathiesand cardiac failures limit life span. Cohorts of thalassemiapatients treated in the chelation era show improved survivaland decreased cardiac deaths. While cited as an examplefor other transfused-related iron overload states, severalcaveats remain. One is that death from iron toxicity in tha-lassemia starts occurring in the second decade of life—atimeframe considerable longer than most patients withacquired anemia [2,3]. Second, considerable controversyremains about the most effective form of chelation [1].Recently, there has been a remarkable increase in anxietyabout transfusion iron overload in acquired hematologic dis-ease states ranging from the bone marrow transplantpatient to patients with myelodysplasia (MDS) [4]. However,a review of this data show this apprehension seems to bebased on selective reading of the literature.One error is the equating of the poor prognosis of need-ing to receive transfusion with the toxicity of iron overload.The relationship between transfusion dependence and pooroutcome in MDS is very clear [5–7]. However, there is lackof correlation with number or duration of transfusion. Theconnection between need for transfusion and poor progno-sis is not surprising and is seen in many other diseasessuch as sickle cell anemia [8]. Indeed, for cancer, overallthe presence of anemia is a significant adverse prognosticfactor [9]. Clearly, many factors related to transfusion otherthan iron overload are responsible for the poorer prognosis.Second, there is increasing use of the serum ferritin as asurrogate for iron overload. The relationship between se-rum ferritin and total body iron stores has always been acontroversial one. Most studies correlating serum ferritinand measure iron stores have found a poor correlation [10–12]. Serum ferritin is a powerful acute phase reactant andlevels even >1000 ng/dl can be seen in inflammatorystates or in liver disease [13,14]. The touted relationshipbetween elevated serum ferritin and poor outcomes in stemcell transplant patients is more a reflection of inflammation/liver toxicity than iron overload from transfusion, especiallybecause most patients in these studies received far 20 units of blood which has been the thresh-old for chelation in many iron overload guidelines.This article by Tefferri’s group shows in another acquiredanemia—primary myelofibrosis—that need for transfusionsis a poor prognostic factor but not peak serum ferritin ortotal transfusions [19]. They studied 185 consecutivepatients evaluated at the Mayo Clinic with a median followup of 28 months. While serum ferritin correlated with trans-fusion need and age, in multivariate analysis, only transfu-sion dependence predicted shorter survival. Of addition im-portance was the finding that need for transfusions was in-dependent of prognosis determined by the newInternational Prognostic Scoring System [20]. These find-ings are consistent with their study of patients with goodprognosis MDS [5]. Together, these studies add to the evi-dence that decreased erythropoiesis—as indicated by needfor transfusions—is a powerful adverse risk factor for sur-vival in these hematological diseases. Conversely, the num-ber of transfusions or the ferritin was not prognostic inthese patients, many receiving chronic transfusions. Thesestudies also show that a group targeted for chelation—patients predicted to have years of transfusions—have noindication of iron toxicity to justify therapy.The plain, simple, unvarnished truth is that there is noevidence to justify the current hysteria over transfusion-related iron toxicity in patients receiving chronic transfusiontherapy. To defend the use of expensive therapy requiresmore than anecdotes, post hoc observations, and studiesusing inaccurate markers of iron stores. To validate the useof chelation therapy requires high-quality studies with truemeasures of tissue iron and of cardiac toxicity showing thatendpoints improve with chelation with benefit to the patient.The challenge in MDS and myelofibrosis is to avoidtransfusions by better therapies to reverse the stem celldefect. Unfortunately, the recent focus on iron overload asa priority and not the stem cell defect is leading to a misal-

What regulates the iron regulator?

Early in my career, we were pretty ignorant about iron (we did not pump it yet), although we did know a few things. We were aware that the daily intake of iron is (should be) about 10 mg and that 1–2 mg of this iron was absorbed. Iron traveled in the blood bound to a carrier protein called “transferrin” and was stored in various places, such as the reticulo-endothelial system (RES) and bone marrow. As a matter of fact, the court-of-last-appeals for iron deficiency was the staining of bone marrow for iron with “Prussian blue”. We were aware that 200 billion erythrocytes were produced daily and that this production would take about 20 mg elemental iron, more than was absorbed. Thus, active recycling had to take place. Total body iron stores were known to be about 5 g and that half this amount resided in the erythrocytes. We were aware of hereditary hemochromatosis (HH), a favorite examination issue by oral examiners who generally had never ever seen a case either. And we knew about the poor Bantus and their ironcontaining cooking-pots. That was about it, although the iron storage mechanism and the way to measure it, namely ferritin, were introduced about 10 years later. The rest was a mystery, including the other common anemia, termed the “anemia of chronic disease”, that not even our smartest professors understood. Fortunately, all that ignorance is behind us, or at any rate, much of it is. Hepcidin (also known as HFE2) is a hepatic iron regulatory hormone that maintains systemic iron homeostasis. Hepcidin is made by the liver and secreted into the blood stream, where it binds to the iron exporter ferroportin that is located on macrophages, hepatocytes, and intestinal enterocytes. Hepcidin causes ferroportin to be internalized and proteolyzed (chewed up). As a result, hepcidin reduces gastrointestinal iron absorption and macrophage-mediated iron recycling. If hepcidin is so critical to iron-metabolic regulation, then the regulation of hepcidin is critical for our understanding how this very basic portion of human physiology works. In this issue, Casanovas et al. shed light on this question [1]. As is now commonly the case, the understanding of a rare Mendelian disease, HH, led the way. We now know that HH can be caused by mutations in a membrane protein encoded by a gene that is similar to those coding MHC class I-type proteins. The protein product associates with beta2-microglobulin (beta2M) and is called “HFE” although I am uncertain why. HFE is thought to regulate iron absorption by influencing the interaction of the transferrin receptor with transferrin. The HH phenotype is also produced by mutations in transferrin receptor 2 (TfR2), hemojuvelin (HJV), or hepcidin itself. Mutations in any of these proteins results in increased duodenal iron absorption, increased macrophage iron release, increased serum iron levels, and liver iron overload. HJV is a member of the “repulsive guidance molecule” (RGM) family, which also includes the bone-morphogenetic protein (BMP) coreceptors RGMA and DRAGON (RGMB). Babitt et al. [2] reported that HJV is a BMP coreceptor and that HJV mutants associated with the HH phenotype have impaired BMP signaling ability. They showed that BMP upregulates hepatocyte hepcidin expression, a process enhanced by HJV, and that is blunted in hepcidin genedeleted hepatocytes. Their data suggested a mechanism by which hepcidin mutations cause hemochromatosis, namely HJV dysfunction decreases BMP signaling, thereby lowering hepcidin expression. Babbitt et al. [3] next showed that BMP-2 administration increases hepcidin expression and J Mol Med (2009) 87:447–449 DOI 10.1007/s00109-009-0453-4

A new 500 kb haplotype associated with high CD8+ T-lymphocyte numbers predicts a less severe expression of hereditary hemochromatosis

BackgroundHereditary Hemochromatosis(HH) is a common genetic disorder of iron overload where the large majority of patients are homozygous for one ancestral mutation in the HFE gene. In spite of this remarkable genetic homogeneity, the condition is clinically heterogeneous, varying from a severe disease to an asymptomatic phenotype with only abnormal biochemical parameters. The recent recognition of the variable penetrance of the HH mutation in different large population studies demands the need to search for new modifiers of its phenotypic expression. The present study follows previous observations that MHC class-I linked genetic markers, associated with the setting of CD8+ T-lymphocyte numbers, could be clinically relevant modifiers of the phenotypic expression in HH, and aimed to find new markers that could be used as more reliable prognostic variables.MethodsHaplotype analysis, including seven genetic markers within a 1 Mb region around the microsatellite D6S105 was performed in a group of 56 previously characterized C282Y homozygous Portuguese patients. Parameters analyzed in this study were total body iron stores, clinical manifestations related with HH and immunological parameters (total lymphocyte numbers, CD4+ and CD8+ T-lymphocyte numbers). An independent group of 10 C282Y homozygous patients from Vancouver, Canada, were also included in this study and analyzed for the same parameters.ResultsA highly conserved ancestral haplotype defined by the SNP markers PGBD1-A, ZNF193-A, ZNF165-T (designated as A-A-T) was found associated with both abnormally low CD8+ T-lymphocyte numbers and the development of a severe clinical expression of HH. In a small proportion of patients, another conserved haplotype defined by the SNP markers PGBD1-G, ZNF193-G, ZNF165-G (designated as G-G-G) was found associated with high CD8+ T-lymphocyte numbers and a milder clinical expression. Remarkably, the two conserved haplotypes defined in Portuguese patients were also observed in the geographically different population of Canadian patients, also predicting CD8+ T-lymphocyte numbers and the severity of disease.ConclusionThese results may have important implications not only for approaching the question of the penetrance of the hemochromatosis gene in different world populations but also to further narrow the region of interest to find a candidate gene involved in the setting of CD8+ T-lymphocyte numbers in humans.

Ferritin for the clinician

Ferritin, a major iron storage protein, is essential to iron homeostasis and is involved in a wide range of physiologic and pathologic processes. In clinical medicine, ferritin is predominantly utilized as a serum marker of total body iron stores. In cases of iron deficiency and overload, serum ferritin serves a critical role in both diagnosis and management. Elevated serum and tissue ferritin are linked to coronary artery disease, malignancy, and poor outcomes following stem cell transplantation. Ferritin is directly implicated in less common but potentially devastating human diseases including sideroblastic anemias, neurodegenerative disorders, and hemophagocytic syndrome. Additionally, recent research describes novel functions of ferritin independent of iron storage.

Intraindividual Comparison between Deferasirox and Deferoxamine in Thalassemia.

In patients with iron overload from chronic blood (RBC) transfusion a new era of chelation treatment has been started with the availability of 3 chelators, their combinations, and other potential modifiers of tissue iron distribution. The decision about the chelator type and its dose would be facilitated if a mean chelation response could be forecasted. With the knowledge of a chelator's molar efficacy, one could calculate the dose necessary to compete with the iron influx from blood transfusions. An open compartment model as developed for deferoxamine (DFO) and deferiprone (DFP) (Brit J Haematol 2003; 121:938–48) would additionally allow to forecast the total body iron store for a given blood transfusion and chelator dose rate over time, also for deferasirox. In a prospective study of the oral chelator deferasirox (DSX, Exjade®), 17 patients with b-thalassemia (age: 4 – 32 y) have been followed for 8 to 38 months by SQUID biomagnetic liver susceptometry in intervals of 6 to 12 months. Retrospectively, the same patients were followed in the past during s.c. DFO treatment. Liver iron concentration LIC, liver volumes, RBC transfusion and chelation dose rates were assessed. Of major importance was the stability of the hematocrit in the RBC units used in our department of 60 ± 3% over more than 6 years. Total body iron stores were calculated from total liver iron taking into account that 80 ± 10% of the total body storage iron is accumulated in the liver. For each measurement interval, molar efficacies were calculated from the daily iron input rate due to RBC plus the change in total body iron stores per interval time, and the molar dose rate of DFO or DSX. Additionally, total body iron elimination (TBIE) rate constants were calculated for each interval and fitted as function of the chelatable iron pool. LIC values, liver volumes, and ferritin levels were measured in the range of 498–8009 μg/g-liver, 654-3208 ml, and between 787 and 14866 μg/l. During DSX and DFO treatment, molar chelation efficacies of 11.2–53.1% and 6.1–23.7% were found for mean dose rates of 0.5–3.2 mmol/d (21–39 mg/kg/d) and 0.9–5.2 mmol/d (25–53 mg/kg/d) applied to iron influx rates of 7.6–30.6 mg/d and 9.7–28.5 mg/d from blood transfusion, respectively. In 6/17 (13/15 for DFO) patients with at least 3 treatment intervals, the intraindividual the molar efficacy ranged from 13.3±1.9% to 39.0±7.2% for DSX and from 7.8±2.0% to 19.4±2.9% for DFO in the same patients. Compliance assessed from tablet count protocols (> 90%) did not influence these data significantly. The mean molar efficacies of 29±10% and 15±5% in our patient group agreed with reference values (Blood 2005; 106(11):#2690 and Brit J Haematol 2003; 121:938–48) for DSX and DFO, respectively. In contrast to DFO and DFP, the compartment model calculations resulted in a linear function of the TBIE rate constant for DSX with no saturation effect over the whole range of chelator doses and LIC. In summary, deferasirox was as efficient as deferoxamine at only half the molar dose even on an intraindividual patient basis. Once the individual molar efficacy has been assessed, a minimum chelator dose can be calculated to compete with the daily iron input from blood transfusions. The compartment model parameters of the total body iron elimination rate constant for deferasirox may allow to forecast the gross time pattern of liver iron concentration changes for practical treatment periods.