Thalassemia major is characterized by
anemia,
iron overload, and
oxidant damage to major organs, especially the cardiovascular system. Oxidative stress is ultimately involved in endothelial dysfunction, a condition which is evident in adults suffering from various
cardiovascular diseases including
thalassemia. We investigated endothelial function in pediatric patients with
hemoglobin E-
beta thalassemia (HbE-
beta thalassemia), who have been exposed to excessive
iron and oxidative stress for much shorter period than adults with
thalassemia. We recruited 22
blood transfusion-dependent HbE-
beta thalassemia patients aged 11.8 +/- 2.9 years and 20 healthy controls aged 12.1 +/- 1.7 years.
Oxidant status was determined, and endothelial function was assessed by a forearm blood flow technique. Oxidative stress was increased in the thalassemic patients, as blood
glutathione (GSH) and ratios of reduced GSH to GSH
disulfide were markedly reduced, and
superoxide anion released from blood cells was highly elevated. Oxidative stress response, assessed by
gamma-glutamylcysteine ligase activity, was increased approximately twofold in
thalassemia patients. Basal forearm blood flow was significantly increased in patients compared with controls (7.3 +/- 1.8 vs 6.0 +/- 1.8 ml/100 ml tissue/min, respectively), whereas forearm vasodilatory response to
reactive hyperemia was depressed by 50% in patients compared with controls. Endothelial function is impaired in young
thalassemia patients, and impaired endothelial function is associated with
oxidant stress.