Pulmonary Dysfunction in Transfusion-dependent Patients with Thalassemia Major

Abstract

Pulmonary function tests were performed on 62 transfusion-dependent patients with thalassemia major, ranging in age from 8 to 33 years, and receiving chelation therapy with desferrioxamine or deferiprone. Percent predicted values for FVC, FEV1, and PEF were significantly reduced, whereas FEV1/FVC and maximal expiratory flow at 25% FVC were within normal limits, indicating a restrictive disease. Both FVC and FEV1 were negatively correlated with transfusional iron burden as indexed by age. Single-breath carbon monoxide transfer factor was reduced, even after correction for low hemoglobin concentration, and was negatively correlated with iron burden and iron overload, as indexed by serum ferritin levels. Owing to low hemoglobin concentration, blood-diffusing capacity was reduced, in spite of increased lung capillary blood volume, which was, however, adequate to normalize blood diffusing capacity when hemoglobin concentration was only partially restored by transfusion. The diffusing capacity of the alveolar-capillary membrane was substantially decreased and negatively correlated with age and serum ferritin, the fall being primarily attributed to increased membrane thickness. These findings suggest that lung fibrosis and/or interstitial edema related to iron overload are the main cause of pulmonary dysfunction observed in patients with thalassemia major.

Comparison of pulmonary functions of thalassemic and of healthy children

“…Among the thalassemic subjects, restrictive lung function abnormality was the most common (42/63) observation documented in this study. Our findings are consistent with those of Carnelli et al, 1 Factor et al, 2 Tai et al, 5 Luyt et al, 6 and Filosa et al 7 What is unique to our study is that it was performed exclusively in children, while those studies mentioned earlier were all performed in both children and adults, with a considerably older mean age. Therefore, our study shows that lung dysfunction in thalassemic patients has occurred since childhood.…”

“…However, no correlation was found between serum ferritin levels and any of the lung function values. This finding supported those discovered by Tai et al, 5 and Luyt et al 6 , but contrasted with studies by Carnelli et al, 1 Factor et al, 2 and Filosa et al 7 It is suggested that the duration of iron overload may be more important than the actual amount of iron provided through transfusions. 2 Moreover, serum ferritin levels change during the process of chelation, and do not necessarily reflect total body iron stores.…”

“…On the other hand, most patients in previous studies had regular and adequate chelation therapy but were still found to have lung dysfunction. [1][2][5][6][7]11 This may lead us to question the effectiveness of chelation therapy. Nevertheless, the lung function values observed in our patients were lower than those in other published studies, which may indirectly reflect the benefit of chelation therapy and the role of iron overload.…”

“…There was no correlation between percentage from predicted forced vital capacity and serum ferritin levels, whether in male (r=0.191; P=0.967) or female (r =-0.076, P=0.695) thalassemic subjects. Keywords: pulmonary function, thalassemia, spirometry, serum ferritin level, restrictive lung dysfunction T halassemia refers to a heterogeneous group of heritable hypochromic anemias of various degrees of severity; [1][2][3][4][5][6][7][8][9] it is considered to be the most prevalent genetic disorder in the world. 3 Transfusions of 15-20 ml/kg of packed cells are usually required every 4-5 weeks.…”

Talasemilerde Solunum Sistemi Bozuklukları

“…Hastaların %55'inin SFT'si normal olarak bulunurken geriye kalan %34'ünde ise difüzyon bozukluğu saptanmıştır 80 . Birçok çalışmada da β -TM tanılı hastalarda temel solunum sistemi bozukluğunun obstrüktif veya restriktif değil difüzyon bozukluğu olduğu öne sürülmüştür 72,80,87 . Bu durumun düşük hemoglobin konsantrasyonunun yanı sıra, ilerleyen zamanlarda alveoler-kapiller membran kalınlığının artışı ile difüzyon kapasitesinde azalma neticesinde görüldüğünü öne sürmüşlerdir.…”