Pulmonary function abnormalities in thalassemia major and the role of iron overload.

Abstract

To determine the predominant abnormality of pulmonary function in patients with thalassemia major (TM), we evaluated 29 patients with TM who were receiving hypertransfusion therapy and chelation with desferrioxamine (DFO), and who ranged in age from 6 to 40 yr (mean 19.8 +/- 8.5 yr). A reduction in the total lung capacity (TLC) was the most striking abnormality, found in 21 of 29 patients (79%). Fourteen of these patients (67%) had a moderate or severe reduction in TLC. Expiratory flow rates, FEV1, and FEF25-75 were decreased below predicted values in 48 and 17% of the patients, respectively, but no patients had pure obstructive disease. Significant hypoxemia (oxygen saturation of less than 95%) was observed in only one patient. There was a significant inverse correlation between TLC and patient age (p < 0.003), transfusional iron burden (p < 0.003) and DFO ratio (p < 0.024). Restrictive disease is the predominant abnormality of pulmonary function in TM, with a mixed restrictive-obstructive pattern in a small number of patients. The restrictive disease becomes more severe with increasing age, and the degree and duration of iron overload appear to be important in its pathogenesis. The role of DFO therapy in preventing the pulmonary complications associated with TM requires further study.

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.…”

“…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. 2 Therefore, a cross-sectional study such as this one, where only the latest serum ferritin level was obtained, lacked the ability to demonstrate the relationship between lung dysfunction and iron overload.…”

“…2 Moreover, serum ferritin levels change during the process of chelation, and do not necessarily reflect total body iron stores. 2 Therefore, a cross-sectional study such as this one, where only the latest serum ferritin level was obtained, lacked the ability to demonstrate the relationship between lung dysfunction and iron overload. A complex mechanism in addition to iron overload has been proposed to play a role in the development of lung dysfunction in thalassemic patients, such as transfusion-dependent chronic fluid accumulation.…”

“…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.…”