Impaired Endothelial Function in Pediatric Hemoglobin E/β-thalassemia Patients with Iron Overload.

Hemoglobin E/β-thalassemia (HbE/β-thalassemia) is the most important type of thalassemia in northeastern Thailand. Serious complications of the disease are associated with iron overload and the consequences of oxidative damage to various organs, especially the cardiovascular system. Endothelial dysfunction is an important predictor for the long-term outcome of the disease. In this study, 19 patients with HbE/β-thalassemia (aged 12.9 ± 2.8 years) and 18 healthy controls (aged 11.8 ± 1.6 years) were enrolled and their oxidant and antioxidant status was determined. Their vascular endothelial function was assessed by ultrasonographic measurement of flow-mediated dilation (FMD) of the brachial artery. The thalassemia patients were found to have higher levels of oxidative stress (based on plasma levels of malondialdehyde and protein carbonyls) and significantly reduced antioxidant levels [based on levels of glutathione (GSH) in whole blood (p < 0.001)]. Thalassemia patients showed endothelial dysfunction as shown by their FMD response during reactive hyperemia (p < 0.001). The degree of impaired FMD response was correlated with the age, hemoglobin levels and serum free iron levels of subjects (p < 0.05). In conclusion, the FMD response was reduced in children with HbE/β-thalassemia and the degree of this reduction was correlated with the severity of anemia. FMD can be used for clinical evaluation of endothelial dysfunction, which could be an independent predictor of the cardiovascular events of thalassemia patients.