Thalassemia syndromes. Biochemical, genetic and clinical aspects

Pulmonary function test in transfusion-dependent β-thalassemia major patients: a pilot study

Lung involvement is one of known complications of thalassemia. The aim of this study was to determine predominant type of pulmonary dysfunction and its relationship to iron overload in β-thalassemia children. Fifty thalassemia major children with treatment of regular blood transfusion and desferrioxamine participated in the study. Thirty-three boys and 17 girls (median age 12.5 years) with β-thalassemia enrolled in the study. Other information including body mass index, hematocrit, and the number of years of blood transfusion were recorded. Serum ferritin level and hematocrit were 3346 ± 1667 mg/dL and 27.7 ± 2, respectively. Pulmonary function tests were performed in all subjects for detecting pulmonary dysfunction. Thirty-five patients (70%) with thalassemia had abnormal result of spirometry. Obstructive airway disease based on reduced forced expiratory volume in 1 second (FEV(1)) and FEV(1)/forced vital capacity (FVC) ratio <80% was detected in 4 patients (8%). Six patients (12%) showed restrictive pattern, as defined by a reduction FVC <80% and FEV(1)/FVC ratio ≥80%. In this study, small airway involvement based on presence of forced expiratory flow (FEF(25%-75%)) <60%, FEV(1)/FVC ratio >70%, and FVC >80% was detected in 25 subjects (50%). Decreased values of peak expiratory flow rate (PEF) were detected in 23 (46%) and low FEV(1) in 10 (20%) subjects. There was no significant correlation between abnormal pulmonary function test and serum ferritin level in children with thalassemia. This study showed small airway disease was predominant abnormality in thalassemia patients, although additional larger studies are needed to evaluate underlying mechanisms and validate these findings.

Antibody titration and immune response of Iranian beta-thalassemic patients to hepatitis B virus vaccine (booster effect)

BACKGROUND

Thalassemia is hereditary anemia with lifelong transfusion as treatment and hepatitis B virus (HBV) infection is one of the transfusion transmitted infections (TTI). HBV vaccination is obligatory for these patients by 3 double-dose injections. The authors studied the HBV status and immune response to vaccination by hepatitis B surface antibody (HBsAb) titration in their thalassemic patients. They also compared these results with their previous study to find out the effectiveness of a booster dose in the immunity of patients against HBV.

MATERIALS AND METHODS

Hepatitis B surface antigen (HBsAg), HBsAb, and hepatitis B core antibody (HBcAb) were detected in sera of 416 patients at the Tehran Adult Thalassemia Clinic. The immune status was classified into 4 categories: (1) immune to HBV via the vaccination (positive vaccinal)--if HBs Ag: negative, HBsAb: positive, HBcAb: negative; (2) immune to HBV via the natural disease (past infection)--if HBs: negative, HBsAb and HBcAb: both positive; (3) nonimmune to HBV (negative)--if all three parameters were negative; (4) carrier of HBV (carrier state)--if HBs Ag was positive and HBsAb and HBc Ab: both negative. Also grading of immunity done by HBsAb titration as positive if HBsAb titer was more than 100 IU/mL, negative if HBsAb titer was less than 10 IU/mL, and weakly positive if antibody level was 10-100 IU/mL.

RESULTS

There were 416 patients: 302 (72.5%) with thalassemia major (TM), 104 (25%) thalassemia intermedia (TI), 7 (1.6%) sickle thalassemia (ST), and 3(0.7%) alpha-thalassemia (HbH disease). The mean age was 25.6 +/- 8.3 yr and median age was 24 yr; there were 247 (59.4%) males and 169 (40.6%) females. A total of 257 patients (61.7%) were splenectomized. According to our classification 289 (69.4%) were immunized by vaccination; 80 (19.2%) were immunized by past infection; 44 (10.5%) were negative, and 3 (0.7%) were in carrier state of HBV. In grading of immunity to HBV vaccination, 319 (76.6%) patients had HBsAb > 100 IU/mL (positive), 77 (18.5%) between 10 and 100 IU/mL (weakly positive), and 20 (4.8%) less than 10 IU/mL (negative). There was no significant correlation between the level of HBsAb and splenectomy or type of thalassemia.

CONCLUSION

Response rate to vaccination is more than 95% after complete course (3 doses) in healthy individuals but failure to fulfill vaccination seems a problem in chronic transfused patients. These results reflect advantages of a booster dose of vaccine, which increased the protection level among these high-risk patients from 46.9% (in the authors' previous data) up to 69.4% in this study.

Pulmonary function test in transfusion-dependent beta-thalassemia patients

Beta-thalassaemia is the most common hemoglobinopathies in our region with treatment of regular blood transfusion. Iron overload and hemosiderosis can cause organ involvement. Recent studies have focused on pulmonary involvement and pathophysiology of lung damage. The goal of this study was to investigate the pulmonary abnormalities in thalassemic patients in relation with sign and symptoms and iron overload. The authors studied pulmonary function test (PFT) at the Adult Thalassemia Clinic in Tehran. The history of blood transfusion, iron chelation, respiratory problems, and drug usage was taken. Physical examination, PFT, arterial blood gas (ABG), and chest X-ray (CXR) were done. In total, 139 patients were studied. The mean age was 21.1 years and mean duration of transfusion was 18 years. It was found that 133 patients (95.7%) did not have respiratory problems and only 6 (4.3%) had some respiratory complaints. In CXR, 100 patients (89.3%) had normal lung pattern and others (10.7%) had variable degrees of abnormal lung pattern. In ABG, mean of Po(2) was 73.5% and mean of O(2) saturation was 90.6%. In PFT, 101 patients (72.7%) had restrictive pattern, 35 (25.1%) had normal pattern, and 3 (2.2%) had combined pattern. According to vital capacity, the patients were placed in five categories: 54 patients (38.8%) normal, 37 (26.6%) mild, 35 (25.3%) moderate, 10 (7.2%) severe, and 3 (2.1%) extremely severe pulmonary deficit. There was no statistical significance between PFT results with all variables studied, except duration of blood transfusion, which may be considered a indirect effect of iron load (p = .05, r = .361). According to these results, restrictive pattern was the most common finding (72.7%) in PFT, while 95.7% of patients had no respiratory complaint, and in the chest X-ray group, 89.3% had normal pattern. The authors conclude that the lung may be considered a site for organ damage, and alteration of pulmonary function may be expected in transfusion-dependent patients in spite of no pulmonary symptoms or normal CXR. In recent years, because of new iron chelating drugs, doctors can expect thalassemic patients to have a long life-time and need to increase their quality of life. One way to do this is to evaluate the respiratory system by PFT to prevent the squeal of pulmonary disease.

Respiratory function in patients with thalassaemia major: relation with iron overload

AIMS

(1) To determine the pattern of respiratory impairment in children with thalassaemia major (TM); (2) to assess the relation between the degree of respiratory impairment and total body iron content.

METHODS

Twenty nine TM patients were recruited. All underwent physical examination, standardised pulmonary function tests (spirometry, lung volume, and single breath diffusion capacity for carbon monoxide), and magnetic resonance imaging measurements of the liver. Serum ferritin was measured. The signal intensity ratio of liver to that of paraspinal muscle (T1 weighted sequence) and serum ferritin were used as surrogate index of body iron content.

RESULTS

Sixteen boys and 13 girls (median age 14.2 years) were studied. None had clinical evidence of congestive heart failure. Sixteen had normal lung function. Impairment of diffusion capacity (median DL(co) 83.5% predicted) was the most common abnormality, being observed in 34% of patients. Pure restrictive and obstructive ventilatory impairment was found in one and two patients respectively. Five patients had a combination of ventilation and diffusion defects. There was no correlation between the degree of impairment of each respiratory abnormality and body iron content.

CONCLUSION

Diffusion impairment was the commonest abnormality found in our cohort of paediatric TM patients. Our data did not support the notion that respiratory function impairment was correlated with body iron content.

Effect of the Leukostop filter on pulmonary function following blood transfusion in patients with thalassemia major

This study evaluated the effect of the Leukostop filter, a device which reduces the number of leukocytes in blood, on pulmonary function in 15 patients with thalassemia major. Spirometry and oxygen saturation were used to evaluate the influence of filtering the blood. The transfusions consisted of blood which had or had not passed through a Leukostop filter. Blood transfusion induced a significant drop in FEV(1)/FVC ratio in 4 patients, an effect which disappeared following use of the Leukostop filter. Oxygen saturation improved after 6 months of using the Leukostop filter and improved acutely following blood transfusion (both with and without the filter). We conclude that removing most of the leukocytes from the blood during transfusions prevents bronchoconstriction and improves oxygen saturation.