الفهرس 
? Sickle Cell DiseaseOnly 14 pages are availabe for public view
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Abstract
Background: Pulmonary involvement in sickle cell disease (SCD) is a source of acute morbidity and, in the long term, a major determinant of survival. Pulmonary surfactant protein D (SP-D) is considered a candidate biomarker for lung integrity and for disease progression. Increased serum levels of SP-D have been reported in several lung diseases. Aim: To determine the level of surfactant protein D (SP-D) in children and adolescents with SCD and assess its possible relation to markers of hemolysis, iron overload and pulmonary complications. Methods: Fifty SCD patients in steady state were studied focusing on transfusion history, hydroxyurea therapy, hematological profile, serum ferritin, serum SP-D levels by enzyme linked immunosorbent assay. Patients were compared with 30 age- and sex-matched healthy subjects (17 males and 13 females) enrolled as controls. High-resolution computerized tomography (HRCT) of the chest and pulmonary function test were performed. Results: HRCT of the chest revealed that 32 (%) of the studied patients had interstitial pulmonary fibrosis grades 1-3. The pulmonary function of the studied patients was classified into normal (50%), obstructive (10%), restrictive (26%), and mixed (14%). SP-D levels were significantly higher in patients compared with controls, particulary patients with sickle cell anemia than those with sickle β-thalassemia. SPD levels were significantly associated with higher incidence of cough and repeated chest infection as well as with increasing severity of interstitial pulmonary fibrosis where the highest levels were found among patients with grade 3. The highest SP-D levels were observed among patients with restrictive lung disease followed by mixed type then obstructive lung disease. Significant positive correlations were found between serum SP-D levels and HbS as well as serum ferritin while SP-D was negatively correlated with duration of hydroxyurea. Moreover, there were significant negative correlations between SP-D and parameters of pulmonary functions (FEV1, FVC, FEF25-75%). ROC curve analysis revealed that SP-D cutoff value 720 ng/mL could significantly detect the presence of abnormal pulmonary function among SCD patients with 72% sensitivity and specificity of 88%. Conclusions: Abnormalities in lung function are common in pediatric patients with SCD and the type of lung disease varies, although restrictive pattern is more common than obstructive or mixed types. Elevated SP-D levels highlight the pathophysiology of pulmonary complications in SCD and are related to HbS, iron overload and parameters of pulmonary function test. SP-D may be considered a promising biomarker for screening of SCD patients at risk of pulmonary complications because it is related to the type and severity of lung disease