The natural history of thalassemia intermedia.

The severity of thalassemia intermedia depends on the degree of imbalance between alpha and non-alpha chains as well as other genetic and environmental factors that modify the natural history of the disease. By definition, the patients spontaneously maintain hemoglobin at or above 7 g/dL, sometimes at the price of intense hyperplasia of the bone marrow that is in turn responsible for bone deformities, osteoporosis, and extramedullary erythropoietic masses that often characterize thalassemia intermedia. Transfusion may become necessary with advancing age, during infection and pregnancy, and when hypersplenism develops. Splenectomy is often needed. Iron overload in nontransfused patients is due to increased gastrointestinal absorption and involves mainly the liver. Complications affecting the lives of patients with thalassemia intermedia include pulmonary hypertension, leg ulcers, pseudoxanthoma elasticum, gallstones, hepatocellular carcinoma, and thromboembolic events.