Morbidities in non-transfusion-dependent thalassemia

Patients with non-transfusion-dependent thalassemia (NTDT) experience a wide array of clinical complications despite their independence from frequent, regular red blood cell (RBC) transfusions. According to the current understanding of NTDT, these clinical complications stem from the interaction of multiple pathophysiological factors: ineffective erythropoiesis, iron overload, and hypercoagulability. The state of chronic anemia and hypoxia-resulting from ineffective erythropoiesis and hemolysis-leads to the expansion of the erythroid marrow and extramedullary hematopoiesis. The chronic ineffective erythropoiesis also triggers increased intestinal iron absorption and deposition in the liver and endocrine glands despite the lack of transfusional iron load. Patients with NTDT also have a higher incidence of thromboembolic disease, pulmonary hypertension, and silent cerebral ischemia. The treatment of NTDT relies on occasional or more frequent blood transfusions for certain indications (severe infection, pregnancy, and surgery), iron chelation therapy, splenectomy, and hydroxyurea. Splenectomy is no longer routinely performed in all patients with NTDT in light of its association with increased risk of NTDT-related complications. This review focuses on the clinical morbidities associated with NTDT, summarizes the mainstays of treatment, and sheds light on future therapeutic directions in the field.