Studies Of Iron Overload And Iron-Induced Complications And Mechanisms In Beta-Thalassemia Major Patients In Guangxi

THE FIRST PART OF THESISSTUDY OF IRON OVERLOAD IN PATIENTS WITH THALASSEMIA MAJOR IN GUANGXIPurpose This study aimed at investigating the prevalence and severity of iron overload in a young Guangxi population with beta thalassemia major (TM).Methods We studied310patients (196males and114females) with beta TM from November2010to January2013. The median age was8(5-25) years. Serum ferritin was measured by electrochemiluminescence immunoassay (ECLIA) in all patients.Results Hepatomegaly and splenomegaly were found in80patients (25.8%) and89patients (22.6%), respectively. Thirty-nine patients (12.6%) received splenectomy treantment. The median number of blood transfused was134(rang2-960)U. Five patients (1.6%) were well-chelated,256patients (82.6%) poorly-chelated and49(15.8%) patients didn’t receive chelation therapy. The median SF value is3917ng/ml.95.4%of all patients had SF>1000ng/ml,76.6%patients had SF>2500ng/ml.Conclusions Most beta-TM patients in Guangxi are younger, poorly-chelated, and have a high burden of iron overload. THE SECOND PART OF THESISSTUDY OF CARDIAC IRON OVERLOAD IN PATIENTS WITH THALASSEMIA MAJORPurpose This study aimed at investigating the occurrence, prevalence and severity of cardiac iron overload in a young Guangxi population with beta thalassemia major (TM).Methods We analyzed T2*cardiac magnetic resonance (CMR), left ventricular ejection fraction (LVEF) and serum ferritin (SF) in201beta TM patients with192children and9adults. The median age was9(4-25) years old.Results Five patients (2.5%) were well-chelated and196patients (97.5%) poorly-chelated. The median SF level was4536(525-23,640) ng/ml and165patients (82.1%) had SF>2500ng/ml. Myocardial iron overload (T2*<20ms) were detected in64children (33.3%) and4adults (44.4%). Severe myocardial iron overload (T2*<10ms) were detected in25children (13%) and1adult (11.1%). Twenty-two patients under10years old (21.4%) had myocardial iron overload, in which3patients were only6years old. No myocardial iron overload was detected in14patients under the age of6years. Cardiac T2*was negatively associated with age (r=-0.328, p=0.000) or SF (r=-0.319, p=0.000). Measured by CMR, the median of LVEF was64%(49%-81%) in175of the TM patients. Five of6patients with a LVEF<56%had myocardial iron overload. The incidence of impaired LVEF in patients with myocardial iron overload was higher than that in patients without myocardial iron overload (8.1%vs0.9%, p=0.021). Eight of10patients with cardiac diseases had myocardial siderosis.Conclusions Most Chinese TM patients have a high burden of iron overload. Myocardial siderosis, which occurred in patients younger than previously reported, was strongly associated with impaired LVEF and cardiac diseases. For those poorly-chelated TM patients, our data suggests that there leaves great room for improvement of patient care and that the first assessment of cardiac T2*should be performed as early as6years old. THE THIRD PART OF THESISSTUDY OF LIVER IRON OVERLOAD IN BETA-THALASSEMIA MAJOR PATIENTSObjective The aim of this study was to study the prevalence and severity of liver iron overload in β-thalassemia major (β-TM) patients, and the relationship of cardiac T2*and liver iron concentration with various clinical and serum biochemical parameters.Methods Cardiac T2*(MRI T2*)、 left ventricle ejection fraction (LVEF) and liver iron concetratin(LIC, MRI R2) were measured in59patients with P-TM by magnetic resonance imaging technique. The median age was (13) years old. Serum ferritin was measured by electrochemiluminescence immunoassay (ECLIA).Results1. The median SF level was6016.5±3566.9ng/(1345-23640 ng/ml) ng/ml and51patients (86.4%) had SF>2500ng/ml.2. The mean value of myocardial T2*was20.5±13.4ms, and LVEF value was70±4.6%. Fifteen patients had mild-moderate cardiac iron overload, and15patients had severe cardiac iron overload. ALL of patients had normal LVEF.3. The mean value of LIC was35.8±10.6mg/g dry weight. Cardiac T2*<20ms were detected in30patients (50.8%). All of59patients had severe liver iron overload, and53patients (89.9%) had LIC>15mg/g dw.4.The30patients(50.8%) with cardiac T2*<20ms had LIC15mg/g dw. And the6patients(10.2%) with LIC<15mg/g dw had normal cardiac T2*.5. LIC was positively correlated with SF(r=0.698,p=0.000) and inersely correlated with cardiac T2*(r=-0.345,p=0.009). There was a positive correlation between AST、 ALT and LIC(r=0.307,p=0.019; r=0.348,p=0.007).6. No correlatian was found between cardiac T2*and SF、 LVEF. There was no correlation between LIC、 cardiac T2*and age of starting blood transfusion、 age of starting chelation therapy and numbet of total blood transfused.Conclusion β-thalassemia major patients had a severe liver and cardiac iron overload status. Liver iron concentration had a positive correction with SF and cardiac T2*. AST and ALT had a positive correction with liver severe iron overload. THE FOURTH PART OF THESISCORRELATION OF NT-PROBNP LEVEL AND CARDIAC IRON OVERLOAD IN PATIENTS WITH BETA-THALASSEMIA MAJORObjective The aim of this study was to investigate the correlation between N-terminal pro-brain natriuretic peptide (NT-proBNP) levels with cardiacT2*and LVEF in patients with β-thalassemia major(β-TM),and investigate the value of NT-proBNP levels in detecting cardiac iron overload and LVEF abnormal.Methods We studied140patientswith beta TM (83males and57females) and30healthy controls (20males and10females). The median age of patiens was8(5-25) years old and the median age of controls was8(5-9) years. NT-proBNP and serum ferritin (SF) were measured by electrochemilumine-scence immunoassay (ECLIA). Cardiac T2*and left ventricle ejection fraction (LVEF) were measured in109patients by magnetic resonance imaging T2*(MRI T2*).Results1, NT-proBNP level in β-TM patients was higher than that in normal controls (137.2±136.5pg/ml vs62.5±55.1pg/ml, p<0.05).2. The mean of NT-proBNP level in48patients with cardiac iron overload was higher than that in61patients without cardiac iron overload (212.5±169.4pg/ml vs107.6±109.3pg/ml, p<0.05). NT-proBNP was negatively associated with cardiac T2*(r=-0.416, p=0.000), and positively correlated with age(r=0.436,p=0.000).3.The mean of cardiac T2*value in109patients was22.8±12.5ms (median23.9ms) and48patients(44%)had cardiac T2*<20ms.29patients (26.6%) had cardiac T2*between10ms and20ms, and19patients (17.4%) had cardiac T2*<10ms.Cardiac T2*was inversely correlated with age and SF. The mean LVEF value was64.9±5.9%.Five patients had LVEF<56%. LVEF was positively correlated with age (r=0.314,p=0.001).No correlation was found between LVEF and SF、 cardiac T2*.Conclusion NT-proBNP levels are significantly increased in P-thalassemia major patient. NT-proBNP was negatively associated with cardiac T2*. NT-proBNP is valuable in detecting cardiac iron overload in β-thalassemia major patients. THE FIFTH PART OF THESISREGULATION OF IRON METABOLISM THROUGH GDF15AND HEPCIDIN IN BETA-THALASSEMIA MAJOR PATIENTSObjective The aim of this study was to assess the level of hepcidin and Growth differentiation factor15(GDF15) in patients with P-thalassemia (β-TM) and to study the correlationships of the serum hepcidin and GDF15levels, the blood transfused and the markers of iron overload.Methods Serum hepcidin、 differentiation factor-15and serum ferritin were measured136patients with β-TM patients,17patients with β-thalassemia intermedia(β-TI) and30healthy controls by enzymelinked immunosorbent assay(ELIAS) and electrochemiluminescence immunoassay(ECLIA).Results1. The level of hepcidin in thalassemia was significantly lower than that in control group (34.0±36.5ng/ml vs146.4±70.8ng/ml).The mean level of hepcidin in136β-TM patients and17β-TI patients were31.5±33.6ng/ml and54.5±51.7ng/ml, respectively. The mean level of hepcidin in patients with β-TM and β-TI was significantly lower than that in control group (p<0.05).No significant differences was found between the hepcidin level of P-TM and β-TI patients (p>0.05).2. The mean level of GDF15in thalassemia patients was significantly higher than that in control group (9960.1±6280.6pg/ml vs70.9±15.2pg/ml).The mean level of GDF15in136β-TM patients and17β-TI patients was9962.4±6527.3pg/ml and9944.6±4506.7pg/ml, respectively. The GDF15level of β-TM and P-TI patients was significantly higher than that in control group (p<0.01). No significant differences was found between the GDF15level of β-TM and P-TI patients (p>0.05).3. The mean level of SF in patients with β-TM and β-TI were5076.5±2662.1ng/ml and3315.6±2827.3ng/ml, respectively. The mean levels of cardiac T2*in patients with β-TM and β-TI were were32.4±15.2ms and23.3±12.1ms, respectively. The median of hepcidin and GDF15in patients with cardiac iron overload (T2*<20ms) were not significantly different with those in patients without cardiac iron overload (T2*>20ms).4. There was no correlation between hepcidin and GDF15with age and gender in both thalassemai patients and normal controls. No other clear correlation was found between hepcidin、GDF15and cardiac T2*and LVEF. Hepcidin level showed a negative relationship with SF(r=-0.364, p<0.01).Conclusion The mean level of GDF15was significantly elevated and the mean level of hepcidin was decreased in patients with β-TM and β-TI compared to the normal controls. Our results may indicate that thalassemia patients are in a state of serious ineffective erythropoiesis and need intensify blood transfusion and chelation therapy. THE SIXTH PART OF THESISOXIDATIVE STRESS AND ANTIOXIDANT ENZYME IN p-THALASSEMIA MAJOR PATIENTSObjective The aim of this study was to evaluate the status of lipid peroxidation and antioxidant in patients with p-thalassemia major (β-TM), and investigate the correlation between the status of lipid peroxidation, antioxidant and iron overload.Methods We analyzed serum malondialdehyde (MDA), nitric oxide (NO), plasma superoxide dismutase (SOD) and serum ferritin in123patients with β-TM and44healthy controls. MDA was measured spectrophotometerically using thiobarbituric acid (TBA). NO was determined by the Griess reaction. Assay of SOD was measured with xanthine oxidase reation.Results1.The mean level of MDA, NO and SOD in β-TM were significantly higher than those in in healthy controls (7.2±2.0ng/ml vs5.4±1.9ng/ml,p=0.000;81.7±21.7ng/ml vs72.0±16.9ng/ml,p=0.024;264.5±56.2U/ml vs238.8±46.1U/ml,p=0.021) respectively.2. All the patients were SF>1000ng/ml and104patients (84.6%)had SF>2500ng/ml.The mean level of cardiac T2*was23.6±12.5ms in98patients with β-TM. The mean level of liver iron concentration (LIC) in42patients with β-TM was37.7±9.1mg/g dry weight. The median of MDA and NO in patients with cardiac T2*<20ms was higher than those in patients with cardiac T2*>20ms. The median of SOD of was not significantly different between the two group.3.There was no correlation between the MDA、 NO、 SOD and the age or gender in patients and normal controls. The MDA, NO, SOD were significantly correlated with SF levels. Serum levels of MDA and NO were positively correlated with LIC, and inversely correlation with cardiac T2*.NO correlation was found between SOD values and LIC or cardiac T2*.Conclusion Our study results suggest that iron overload causes peroxidative damage in P-TM and the antioxidant system reation is to compensate for reducing lipid peroxidation to avoid tissue damage.