Organ-specific hemosiderosis and functional correlation in Chinese patients with thalassemia intermedia and hemoglobin H disease

Αlpha-thalassemia: A practical overview

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and β globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

Early development of decreased β-cell insulin secretion in children and adolescents with hemoglobin H disease and its relationship with levels of anemia

BACKGROUND

Diabetes mellitus (DM) associated with iron overload has been reported among adults with transfusion-dependent thalassemia and those with non-transfusion-dependent thalassemia (NTDT), especially in β-thalassemia disease. However, little is known about glucose metabolism and how early its dysregulation can develop in α-thalassemia hemoglobin H (Hb H) disease, which is one of the most common types of NTDT worldwide.

PROCEDURE

We prospectively calculated glucose metabolism index in 40 patients (aged 10-25 years) with Hb H disease. Glucose metabolism data were compared between patients with deletional versus nondeletional Hb H, and between patients with normal versus abnormal insulin secretion/sensitivity.

RESULTS

Despite normal glucose tolerance in all patients, 52.5% had abnormal insulinogenic index indicating decreased β-cell insulin secretion. Patients with functional hemoglobin < 8 g/dL had significantly higher percentages of abnormal insulinogenic index. There was no significant difference in abnormal insulinogenic index between deletional and nondeletional Hb H.

CONCLUSION

Decreased β-cell insulin secretion is highly prevalent among children and adolescents with Hb H disease, and it is associated with levels of functional anemia at baseline, but not with the type of Hb H disease. This result warrants heightened awareness among hematologists due to potentially increased risk of DM later in life.

Cardiac complications in beta-thalassemia: From mice to men

Beta-thalassemia is an inherited hemoglobin disorder caused by reduced or absent synthesis of the beta globin chains of hemoglobin. This results in variable outcomes ranging from clinically asymptomatic to severe anemia, which then typically requires regular blood transfusion. These regular blood transfusions can result in an iron overload condition. The iron overload condition can lead to iron accumulation in various organs, especially in the heart, leading to iron overload cardiomyopathy, which is the major cause of mortality in patients with thalassemia. In the past decades, there is no doubt that the use of β-thalassemic mice as a study model to investigate the pathophysiology of iron overload cardiomyopathy and the role of various pharmacological interventions, has shed some light in understanding this serious complication and in improving the associated cardiac dysfunction. In this review, the effects that iron overload has on the hearts of β-thalassemic mice under conditions of iron overload as well as the efficacy of pharmacological interventions to combat these adverse effects on the heart are reviewed and discussed. The in-depth understanding of biomolecular alterations in the heart of these iron overload thalassemic mice will help give guidance for more effective therapeutic approaches in the near future. Impact statement Iron overload cardiomyopathy is a major cause of morbidity and mortality in patients with thalassemia. Since investigation of iron overload cardiomyopathy in thalassemia patients has many limitations, a search for an animal model for this condition has been ongoing for decades. In the past decades, there is no doubt that the use of β-thalassemic mice as a study model to investigate the pathophysiology of iron overload cardiomyopathy and the role of various pharmacological interventions, has shed some light in understanding this serious complication and in improving the associated cardiac dysfunction. In this review, the effects of iron overload on the hearts of β-thalassemic mice under conditions of iron overload as well as the efficacy of pharmacological interventions to combat these adverse effects on the heart are reviewed and discussed.

Benign Cardiac Effects of Hemoglobin H Disease

BACKGROUND/AIMS

Hemoglobin H (HbH) disease is associated with iron overload, but whether this results in serious cardiac or vascular sequelae is unresolved.

METHODS

We identified 39 adult subjects (age 42 ± 12 years, 13 men) with HbH disease who had undergone echocardiography, 27 of whom had also undergone cardiac and liver magnetic resonance assessment of iron loading using T2*-weighted imaging.

RESULTS

None of the subjects had a history of heart failure or arrhythmias. There were 13/39 subjects with a ferritin level within the sex-based normal range and only 4/39 had ferritin >1,000 ng/ml. Left ventricular (LV) and left atrial dilatation was common, but LV ejection fraction was normal (≥55%) in all subjects. Age was positively correlated with log ferritin in the 27 nontransfused subjects (r = 0.43) and was inversely correlated with the transmitral E wave and E/A ratio (r = -0.69 and r = -0.79, respectively), but no relation of log ferritin with E or E/A was evident. The peak tricuspid regurgitation velocity was normal in 24/29 subjects for whom this was obtained, and it was no more than mildly elevated in the other 5. None of the tested subjects had an abnormal cardiac T2* reading, but half had evidence of liver iron loading.

CONCLUSION

No myocardial iron loading or serious cardiac or vascular sequelae were identified in this cohort with HbH disease.

Efficacy and safety of iron-chelation therapy with deferoxamine, deferiprone, and deferasirox for the treatment of iron-loaded patients with non-transfusion-dependent thalassemia syndromes

The prevalence rate of thalassemia, which is endemic in Southeast Asia, the Middle East, and the Mediterranean, exceeds 100,000 live births per year. There are many genetic variants in thalassemia with different pathological severity, ranging from a mild and asymptomatic anemia to life-threatening clinical effects, requiring lifelong treatment, such as regular transfusions in thalassemia major (TM). Some of the thalassemias are non-transfusion-dependent, including many thalassemia intermedia (TI) variants, where iron overload is caused by chronic increase in iron absorption due to ineffective erythropoiesis. Many TI patients receive occasional transfusions. The rate of iron overloading in TI is much slower in comparison to TM patients. Iron toxicity in TI is usually manifested by the age of 30-40 years, and in TM by the age of 10 years. Subcutaneous deferoxamine (DFO), oral deferiprone (L1), and DFO-L1 combinations have been effectively used for more than 20 years for the treatment of iron overload in TM and TI patients, causing a significant reduction in morbidity and mortality. Selected protocols using DFO, L1, and their combination can be designed for personalized chelation therapy in TI, which can effectively and safely remove all the excess toxic iron and prevent cardiac, liver, and other organ damage. Both L1 and DF could also prevent iron absorption. The new oral chelator deferasirox (DFX) increases iron excretion and decreases liver iron in TM and TI. There are drawbacks in the use of DFX in TI, such as limitations related to dose, toxicity, and cost, iron load of the patients, and ineffective removal of excess iron from the heart. Furthermore, DFX appears to increase iron and other toxic metal absorption. Future treatments of TI and related iron-loading conditions could involve the use of the iron-chelating drugs and other drug combinations not only for increasing iron excretion but also for preventing iron absorption.

Diabetes mellitus in patients with thalassemia major

BACKGROUND

Diabetes mellitus is a major endocrinopathy for patients with thalassemia major. Although diabetes mellitus is multifactorial, iron loading is its primary cause and its management poses a clinical challenge. Detecting the pre-diabetes stage is critical because clinical diabetes can potentially be reversed or prevented.

PROCEDURE

Patients with thalassemia major who received regular blood transfusion therapy from 1994 to 2010 were evaluated for the incidence of diabetes mellitus and glucose dysregulation. The association between patients' clinical, biochemical, and image parameters was also evaluated.

RESULTS

The patients with diabetes were significantly older, had higher ferritin levels, a smaller pancreas volume, and lower cardiac T2* magnetic resonance imaging (MRI) values than the patients without diabetes. The pancreas T2* MRI values were higher in the patients without diabetes, but the difference was not statistically significant. The liver iron concentration did not differ between the patients with and without diabetes. The prevalence of hepatitis C infection and hypogonadism was also higher in the patients with diabetes. In the patients without diabetes, the cardiac T2* MRI values were higher in patients with normal fasting glucose levels (P = 0.03), and the homeostasis model assessment of insulin resistance level was associated with hepatitis C infection (P = 0.024, r = 0.32) and hypogonadism (P = 0.034, r = 0.301).

CONCLUSIONS

Fasting glucose and insulin levels were appropriate screening tools for evaluating glucose dysregulation and complemented the MRI findings. The cardiac T2* and pancreas volumes were significant predictors of diabetes.

An ironic case of liver infections: Yersinia enterocolitis in the setting of thalassemia

A 49 years old Vietnamese male with a history of thalassemia, presented with gastrointestinal symptoms and signs of hemolysis. He was diagnosed with yersinia enterocolitis. Yersinia is a gram-negative rod that most frequently occurs in children especially during the winter months. In the current case, the bone marrow biopsy showed hemophagocytosis along with positive cultures for Yersinia. The microorganism likely triggered hemophagocytosis. This syndrome, also known as, hemophagocytic lymphohistiocytosis, is defined by fever for more than 7 d, cytopenia of two or more cell lines, hemophagocytosis, hepatitis, serum ferritin greater than 500, jaundice, lymphadenopathy, and hepatosplenomegaly. This disorder can be either familial or secondary to a strong immunologic activation. Both have an overwhelming activation of T-cells and macrophages.

Deferasirox for the treatment of iron overload in non-transfusion-dependent thalassemia

Non-transfusion-dependent thalassemia (NTDT) defines a group of patients who do not require regular transfusions for survival, but are at significant risk of iron accumulation from underlying disease-related mechanisms distinct from transfusional iron overload. Management of iron overload in NTDT has received little attention compared with that of β-thalassemia major, despite evidence of significant iron-induced complications with advancing age. The efficacy and safety of the iron chelator deferasirox in NTDT has been evaluated in two pilot studies and the first prospective, randomized, placebo-controlled study (THALASSA) of any chelator in NTDT. Treatment with deferasirox for up to 2 years yielded a sustained reduction in iron burden, with a clinically manageable safety profile. Following these trial data, deferasirox is the first iron chelator approved for use in NTDT patients, and with NTDT guidelines now available, physicians are better equipped to achieve effective monitoring and management of iron burden in NTDT.

Clinical manifestations of α-thalassemia

α-Thalassemia mutations affect up to 5% of the world's population. The clinical spectrum ranges from an asymptomatic condition to a fatal in utero disease. Hemoglobin H disease results from mutations of three α-globin genes. Deletional forms result in a relatively mild anemia, whereas nondeletional mutations result in a moderate to severe disease characterized by ineffective erythropoiesis, recurrent transfusions, and growth delay. Hemosiderosis develops secondary to increased iron absorption, as well as transfusion burden. Hemoglobin Bart's hydrops fetalis is usually a fatal in utero disease caused by the absence of α genes. Population screening to identify at-risk couples is essential. Affected pregnancies result in severe fetal and maternal complications. Doppler ultrasonography with intrauterine transfusion therapy may improve the fetal prognosis but creates ethical challenges for the family and health providers.

Treating iron overload in patients with non-transfusion-dependent thalassemia

Despite receiving no or only occasional blood transfusions, patients with non-transfusion-dependent thalassemia (NTDT) have increased intestinal iron absorption and can accumulate iron to levels comparable with transfusion-dependent patients. This iron accumulation occurs more slowly in NTDT patients compared to transfusion-dependent thalassemia patients, and complications do not arise until later in life. It remains crucial for these patients' health to monitor and appropriately treat their iron burden. Based on recent data, including a randomized clinical trial on iron chelation in NTDT, a simple iron chelation treatment algorithm is presented to assist physicians with monitoring iron burden and initiating chelation therapy in this group of patients. Am. J. Hematol. 88:409–415, 2013. © 2013 Wiley Periodicals, Inc.

MRI of cardiac iron overload

Transfusion therapy has greatly improved the survival of transfusion dependent thalassemia major (TM) patients; however, the resultant iron load damages tissues including the heart, liver and endocrine organs. Among these, heart complication still remains the leading cause of mortality. Myocardial iron deposition can occur independently of other solid organ involvement; conversely, the heart may be spared despite heavy siderosis in other tissues. Iron chelation treatment diminishes the risk of hemosiderosis; however, the chelation treatment has its own toxicities and might not be available to all patients due to costs. Close monitoring of individual organ iron concentration and function is thus important for optimization of individual patient care. This review outlines the importance and clinical significance of recently available MRI techniques for monitoring cardiac iron load.

Iron overload in non-transfusion-dependent thalassemia: a clinical perspective

Iron overload due to increased intestinal iron absorption represents an important clinical problem in patients with non-transfusion-dependent thalassemia (NTDT), particularly as they advance in age. Current models for iron metabolism in patients with beta (β)-thalassemia intermedia (TI) suggest that suppression of serum hepcidin results in increased iron absorption and release of iron from the reticuloendothelial system, leading to depletion of macrophage iron, relatively low levels of serum ferritin, and liver iron loading. The clinical consequences of iron overload in patients with NTDT are multifactorial and include endocrinopathy, bone disease, thromboembolism, pulmonary hypertension, cerebrovascular and neuronal damage, liver fibrosis or cirrhosis, and increased risk of hepatocellular carcinoma. Although serum ferritin levels correlate with liver iron concentration (LIC), they underestimate iron load in these patients compared with transfusion-dependent patients with equivalent LIC. Therefore, direct measurement of LIC is recommended with chelation therapy as indicated.

β-thalassemia intermedia: a clinical perspective

Our understanding of the molecular and pathophysiological mechanisms underlying the disease process in patients with β-thalassemia intermedia has substantially increased over the past decade. Earlier studies observed that patients with β-thalassemia intermedia experience a clinical-complications profile that is different from that in patients with β-thalassemia major. In this article, a variety of clinical morbidities are explored, and their associations with the underlying disease pathophysiology and risk factors are examined. These involve several organs and organ systems including the vasculature, heart, liver, endocrine glands, bone, and the extramedullary hematopoietic system. The effects of some therapeutic interventions on the development of clinical complications are also discussed.

Impact of magnetic resonance imaging on cardiac mortality in thalassemia major

PURPOSE

To evaluate whether the introduction of magnetic resonance imaging (MRI) in the management of thalassemia major (TM) patients has affected the risk of cardiac death.

MATERIALS AND METHODS

In all, 804 TM patients from two large reference units were included and the risk of dying of cardiac causes, before and after their first MRI, was assessed by a Cox proportional hazards model with time-dependent covariates.

RESULTS

Adding information from MRI reduced the risk of cardiac death from 6.0 deaths/1000 patient-years to 3.9 deaths/1000 patient-years (P = 0.22). The risk of cardiac death before having an MRI study was 82% higher compared to the risk observed after the first MRI.

CONCLUSION

MRI has become a vital component of ongoing management and seems to have a beneficial effect on cardiac mortality in TM.

Survival in a large cohort of Greek patients with transfusion-dependent beta thalassaemia and mortality ratios compared to the general population

BACKGROUND

With transfusions and chelation therapy, the prognosis for transfusion-dependent beta thalassaemia has changed from being fatal in early childhood to a chronic disorder with prolonged survival.

DESIGN AND METHODS

  In this historical prospective study, we present survival, causes of death and mortality ratios compared to the general population in 1044 Greek patients with transfusion-dependent beta thalassaemia.

RESULTS

  At the age of 50years, the overall survival was 65.0%, while the cardiac death-free survival was 77%. Birth cohort had a significant effect on survival (P<0.001) with a negative trend towards past decades. The standardised mortality ratio (standardised for sex and ages 20-40years) compared to the general population improved significantly from 28.9 in 1990-1999 to 13.5 in 2000-2008, while the standardised cardiac mortality ratio reduced from 322.9 to 106.6, respectively.

CONCLUSIONS

 Survival in thalassaemia has dramatically improved over the last twenty years but mortality remains significantly increased, compared to the general population.

Myocardial iron overload assessed by magnetic resonance imaging (MRI)T2* in multi-transfused patients with thalassemia and acquired anemias

BACKGROUND

Cardiac complications secondary to iron overload remain a significant matter in patients with transfusion dependent anemias.

PATIENTS AND METHODS

To evaluate cardiac siderosis, Magnetic resonance imaging T2* (MRI T2*) was performed in 3 cohorts of transfusion dependent patients: 99 with thalassemia major (TM), 20 with thalassemia intermedia (TI), and 10 with acquired anemias (AA). Serum ferritin was measured and all patients underwent echocardiographic evaluation.

RESULTS

In TM patients cardiac T2* pathologic values (below 20 ms) were found in 37 patients. Serum ferritin was negatively associated with age (r=-0.32, p=0.001) and weakly with T2* values (r=-0.19, p=0.057). A positive correlation was found between T2* and LVEF (r=0.27, p=0.006). Out of 37 patients with T2*<20 ms, 18 (48%) had serum ferritin values<1000 ng/ml. In TI cohort, 3 patients had cardiac T2* pathologic values. In AA cohort, pathologic T2* values were found in 2 patients, who received 234 and 199 PRBC units, respectively, and were both on chelation therapy (in one patient ferritin value was 399 ng/ml). T2* values were negatively associated, but not significantly, with the number of PRBC transfused (r=-0.53, p=0.07).

CONCLUSION

In our experience, 37% of TM patients had a myocardial iron overload assessed by MRI T2*; this value is higher than in TI patients. Serum ferritin measurement was a poor predictor of myocardial siderosis. In patients with AA, more than 200 PRBC units transfused were required to induce cardiac hemosiderosis, in spite of chelation therapy and, in one patient, of normal ferritin values.

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.