β-Thalassemia and pulmonary function

Background and Objective. The survival of patients with β-thalassemia major and intermedia has improved considerably. This has focused attention on the long-term sequelae of the disease itself and its treatment. The effect of hemosiderosis in major organs (heart, liver, etc) are well-recognized, but the pathophyisology of any lung damage is less clearly understood. We studied lung function changes in 32 patients with β-thalassemia. Design and Methods. Respiratory function tests, CO diffusion and arterial blood gas analysis were performed on 19 patients with β-thalassemia major (9 F, 10 M) and 13 with β-thalassemia intermedia (6 M, 7 F). All investigations were performed 24 hours before the patients received a blood transfusion or when they were in a stable hematologic condition. Echocardiography was performed in all patients and the ejection fraction was employed as a measure of cardiac function. Results. No patient had clinical signs of pulmonary dysfunction. Pulmonary function tests, however, showed a reduction of all main parameters (TLC, FVC, FEV₁ and RV) in most patients with β-thalassemia major, indicating a restrictive type of dysfunction. The pulmonary function of patients with β- thalassemia intermedia seemed to be preserved. Arterial blood gas values were within the normal range, while in some subjects CO diffusion approached the lower limits of normality. There was no evidence that the observed abnormalities in pulmonary function were secondary to congestive heart failure. Interpretation and Conclusions. Iron deposition due to repeated blood transfusions may play a central role in determining lung alterations although the majority of patients are well chelated, suggesting that more than one causal mechanism could be involved.