β-Thalassemia Major: Thin-Section CT Features and Correlation with Pulmonary Function and Iron Overload

Pulmonary function in patients with transfusion-dependent thalassemia and its associations with iron overload

In patients with transfusion-dependent thalassemia (TDT), pulmonary function impairment has been reported but data are conflicting. Moreover, it remains unclear whether pulmonary dysfunction is associated with iron overload. This study aimed to evaluate the pulmonary function in patients with TDT and to investigate the associations between pulmonary dysfunction and iron overload. It was a retrospective observational study. 101 patients with TDT were recruited for lung function tests. The most recent ferritin levels (pmol/L) and the magnetic resonance imaging (MRI) measurements of the myocardial and liver iron status, as measured by heart and liver T2* relaxation time (millisecond, ms) respectively, were retrieved from the computerized medical records. Only data within 12 months from the lung function measurement were included in the analysis. The serum ferritin, and the cardiac and liver T2* relaxation time were the surrogate indexes of body iron content. The threshold of abnormality in lung function was defined as under 80% of the predicted value. 101 subjects were recruited with a mean age of 25.1 years (standard deviation (SD) 7.9 years). Thirty-eight (38%) and five (5%) demonstrated restrictive and obstructive lung function deficits, respectively. A weak correlation of FVC %Predicted and TLC %Predicted with MRI myocardial T2* relaxation time (rho = 0.32, p = 0.03 and rho = 0.33, p = 0.03 respectively) was observed. By logistic regression, MRI cardiac T2* relaxation time was negatively associated with restrictive lung function deficit (B - 0.06; SE 0.03; Odds ratio 0.94; 95% confidence interval (CI) 0.89-0.99; p = 0.023) after adjusting for age, sex and body mass index. Restrictive pulmonary function deficit was commonly observed in patients with TDT, and the severity potentially correlates with myocardial iron content. Monitoring of lung function in this group of patients, particularly for those with iron overload, is important.

Pulmonary functions in Egyptian children with transfusion-dependent β-thalassemia

BACKGROUND

In β-thalassemia, there are varying degrees of ineffective haematopoiesis, intermittent haemolysis and iron overload. Excess iron is deposited in organs such as the heart, the liver, the endocrine glands and the lungs.

OBJECTIVES

To evaluate the pulmonary functions in asymptomatic beta thalassemic children on regular transfusion therapy and their relation to iron overload.

METHODS

The study included 50 transfusion-dependent β-thalassemic children and 50 apparently healthy children as control. All children had undergone pulmonary function tests (spirometry, lung volumes and diffusion capacities). In addition, test to determine the mean serum ferritin of the last 2 years and pre-transfusion haemoglobin and chest radiograph and echocardiography were performed for the thalassemic children only.

RESULTS

A total of 70% of the thalassemic children had diffusion impairment, whereas 34% of them had associated restrictive abnormality. Thalassemic children with serum ferritin >2500 ng mL^-1 had significantly lower values of forced vital capacity (FVC), forced expiratory volume at one second (FEV1), peak expiratory flow (PEFR), total lung capacity (TLC) and diffusing capacity of carbon monoxide (DLCO) (P < 0·05). Only diffusion impairment had a significant positive correlation with serum ferritin level. Restrictive impairment had significant positive correlations with age, duration of blood transfusion and serum ferritin level and a significant negative correlation with duration of chelation (P < 0·05). Having a serum ferritin >2500 ng mL^-1 was the only predicting factor for diffusion impairment and the strongest predicting factor for restrictive dysfunction.

CONCLUSION

Despite being asymptomatic, the majority of thalassemic children in this study suffered from diffusion impairment either alone or in combination with restrictive dysfunction. These pulmonary dysfunctions correlated significantly with body iron stores measured by serum ferritin.

Expiratory air trapping on thoracic computed tomography. A diagnostic subclassification

RATIONALE

Multiple causes for air trapping as identified by expiratory computed tomography (CT) have been reported, but a unified evaluation schema has never been proposed.

OBJECTIVES

It was our purpose to identify imaging features that would help distinguish etiologies of mosaic air trapping.

METHODS

Cases with the term "air trapping" in the radiology report in 2010 were identified by searching the Radiology Information System of an academic tertiary care center and associated community hospital. Medical records and CT examinations were reviewed for the causes of air trapping.

MEASUREMENTS AND MAIN RESULTS

Causes for moderate to severe air trapping could be identified in 201 of 230 (87.4%) cases and could be subdivided into those associated with bronchiectasis (76 of 201, 38%), those associated with interstitial lung disease (62 of 201, 31%), those associated with tree-in-bud opacities (5 of 201, 2%), and those with air trapping alone (58 of 201, 29%). When found with bronchiectasis, nontuberculous mycobacteria, cystic fibrosis, idiopathic bronchiectasis, and transplant-related bronchiolitis obliterans were the most common causes of air trapping. When found with interstitial lung disease, sarcoidosis, hypersensitivity pneumonitis, or unspecified interstitial lung disease were the most common cause of air trapping. When found in isolation, chronic bronchitis, asthma, bronchiolitis obliterans, and unspecified small airways disease were the most common causes of air trapping. Unusual conditions causing isolated air trapping included vasculitis and diffuse idiopathic neuroendocrine cell hyperplasia.

CONCLUSION

A variety of conditions can cause air trapping. Associated imaging findings can narrow the differential diagnosis.

HFE gene variants and iron-induced oxygen radical generation in idiopathic pulmonary fibrosis

In idiopathic pulmonary fibrosis (IPF), lung accumulation of excessive extracellular iron and macrophage haemosiderin may suggest disordered iron homeostasis leading to recurring microscopic injury and fibrosing damage. The current study population comprised 89 consistent IPF patients and 107 controls. 54 patients and 11 controls underwent bronchoalveolar lavage (BAL). Haemosiderin was assessed by Perls' stain, BAL fluid malondialdehyde (MDA) by high-performance liquid chromatography, BAL cell iron-dependent oxygen radical generation by fluorimetry and the frequency of hereditary haemochromatosis HFE gene variants by reverse dot blot hybridisation. Macrophage haemosiderin, BAL fluid MDA and BAL cell unstimulated iron-dependent oxygen radical generation were all significantly increased above controls (p<0.05). The frequency of C282Y, S65C and H63D HFE allelic variants was markedly higher in IPF compared with controls (40.4% versus 22.4%, OR 2.35, p=0.008) and was associated with higher iron-dependent oxygen radical generation (HFE variant 107.4±56.0, HFE wild type (wt) 59.4±36.4 and controls 16.7±11.8 fluorescence units per 10(5) BAL cells; p=0.028 HFE variant versus HFE wt, p=0.006 HFE wt versus controls). The data suggest iron dysregulation associated with HFE allelic variants may play an important role in increasing susceptibility to environmental exposures, leading to recurring injury and fibrosis in IPF.

Restrictive pulmonary dysfunction and its predictors in young patients with β-thalassaemia major

BACKGROUND

Pulmonary dysfunction represents one of the most undervalued and less recognized complications in patients with β-thalassaemia.

OBJECTIVES

The aim of this study was to assess the pattern of pulmonary dysfunction and consequently to investigate possible associated factors that might contribute to lung impairment in young patients with β-thalassaemia major.

METHODS

Fifty-two children and young adults (mean age: 21.33 ± 6.24 years) with β-thalassaemia major on conventional treatment (transfusions and iron chelation therapy) were included in the study. A complete computerized pulmonary function testing (PFT) system for recording pulmonary diffusion capacity and simultaneous determination of alveolar volume and pulmonary volumes was equipped.

RESULTS

Results showed that 20 patients (38.46%) had restrictive pulmonary pattern that was preferentially observed in older and shorter patients. Serum ferritin levels were higher in the restrictive group (2,096 ± 1,831 ng/dl) compared to patients with normal pulmonary function (1,354 ± 942 ng/dl) (P = 0.066). Diffusional impairment characterized by significantly lower DLCO*% values, was observed in the restrictive group (P = 0.004), implicating the 62.5% of the population studied. Paired linear correlations showed that age was negatively correlated to DLCO*% (r = -0.548, P < 0.001) and SaO(2) % (r = -0.789, P < 0.001) and with most of the pulmonary functional parameters that determine a restrictive. Multivariate regression analysis identified age as the major predictor for restrictive pulmonopathy followed by serum ferritin levels.

CONCLUSIONS

Our study shows that pulmonary impairment is shown in a great proportion even among asymptomatic young thalassaemic patients, thus, regular screening of pulmonary function should be adopted in the routine clinical follow up of these patients.

Pulmonary function in thalassaemia major and its correlation with body iron stores

This study compared pulmonary function tests (PFTs) with cardiac, pancreatic and liver iron in 76 thalassemia major (TM) patients. Restrictive lung disease was observed in 16%, hyperinflation in 32% and abnormal diffusing capacity in 3%. While no patients met Global Initiative for Chronic Lung Disease criteria for airways obstruction, there were indicators of small airways disease and air trapping. PFTs did not correlate with somatic iron burden, blood counts or haemolysis. Restrictive lung disease was associated with inflammation. We conclude that TM patients have pulmonary abnormalities consistent with small airways obstruction. Restrictive disease and impaired diffusion are less common.

Study of pulmonary function tests in thalassemic children

The present study aimed to investigate pulmonary function tests (PFTs) in children with thalassemia and to assess the relation between the degree respiratory impairment with the body iron status. High resolution computed tomography of chest (CHRCT) and bronchoalveolar lavage (BAL) was performed to study the cause of pulmonary dysfunction. Thirty-one children with thalassemia over 8 years were included. PFTs were studied including lung volumes and carbon monoxide diffusion capacity (DLco). Patients with abnormal PFTs and/or impaired DLco were further subjected to CHRCT and BAL. Total cell count was measured; differential count was performed on Giemsa and PAP smears. Iron laden macrophages were identified on Perl's stain. PFTs were normal in 51.61%, diffusion capacity impaired in 41.16%, restriction in 16.12%, while obstruction in 3.22% of cases, respectively. There was significant inverse correlation between DLco and serum ferritin. Through multivariate regression analysis, ferritin was found to be a strong predictor for forced vital capacity and total lung capacity. Bronchial dilatation and areas of air trapping were the predominant CHRCT findings. Iron laden macrophages were demonstrated in 14 of 15 patients in BAL. A significant correlation between serum ferritin and DLco, forced vital capacity, total lung capacity, and the presence of iron laden macrophages in BAL indicates that iron plays a major role in the etiopathogenesis of these abnormalities.

Quantification of siderophages in bronchoalveolar fluid in transfusional and primary pulmonary hemosiderosis

Transfusional iron overload may occur in the lungs. We hypothesized that quantitating siderophages in the bronchoalveolar fluid (BALF) of heavily transfused patients may prove to be a useful tool in determining lung iron overload in transfusion-dependent patients. The study included six patients (7-20 years) with thalassemia major (TM) who had received multiple blood transfusions, one with hereditary spherocytosis (four blood transfusions) and one with sickle cell disease (never transfused); they were compared to three children with idiopathic pulmonary hemosiderosis (IPH) (2.5-7.0 years) as positive controls. Fiberoptic bronchoscopy with bronchoalveolar lavage was performed in seven patients under general anesthesia for elective surgery and the rest were bronchoscoped electively under sedation. Spirometry was also performed in eight patients. There was no significant difference between children with TM and IPH in siderophages as percentage of total count (95% CI -31.0 to 1.5, P = 0.068). There were positive relationships between both mean serum ferritin values during the preceding year and the total number of units of transfused blood, and percent siderophage count among multiply transfused patients (P = 0.010, P = 0.052, respectively); similar findings were noted for the Golde score (P = 0.001, P = 0.031, respectively). None of the patients showed lung function impairment. In conclusion, in this small study, we found that the BALF of multiply transfused patients with benign hematological disorders contain similar numbers of siderophages to that of patients with IPH; this is strongly suggestive of secondary pulmonary hemosiderosis. The correlation between the patients' serum ferritin, and the BALF siderophages suggests that the later may serve as a marker of pulmonary iron overload in patients requiring blood transfusion and appear to be more sensitive than standard pulmonary function tests.